JP6863868B2 - Retractable loading platform lifting device - Google Patents

Description

The present invention relates to a retractable loading platform elevating device that supports loading and unloading work of luggage and the like on a loading platform of a vehicle.

The loading platform elevating device raises and lowers the loading platform between the floor height of the loading platform of the vehicle and the ground height, and supports the loading and unloading work of luggage and the like on the loading platform of the vehicle. Some of the cradle elevating devices are retractable devices that are retracted to the underside of the vehicle frame to store the cradle. The retractable cradle elevating device is generally configured so that the cradle slides along a guide rail attached to the underside of the vehicle frame and the cradle moves in and out of the space under the chassis. In this type of load receiving platform elevating device, a fall prevention member including a first member and a second member facing each other may be provided (see Patent Document 1 and the like). The first member is provided on the guide rail, and the second member is provided on the cradle. By facing the first member and the second member, the lowering of the cradle in the retracted state is mechanically restricted.

JP-A-2017-132392

In the loading platform elevating device of Patent Document 1, the loading platform is brought into contact with the guide rail in order to reliably raise the loading platform to the height of the retracted posture when the loading platform is retracted. That is, the loading platform in the retracted posture is in contact with the guide rail. Therefore, when the load receiving table is pulled out and the lock by the fall prevention member is released, the bottom pressure of the lift cylinder is released for a short time in order to suppress the friction between the load receiving table and the guide rail. For a short time when the bottom pressure of the lift cylinder is released, the load receiving table is allowed to descend due to its own weight.

However, the hydraulic oil leaks to the hydraulic circuit due to the decrease in viscosity or expansion of the hydraulic oil, and the loading platform may gradually lower with the passage of time. The distance between the first member and the second member of the fall prevention member is set at the design stage, but if the distance is small due to individual differences, for example, the first member with the passage of time (for example, after one day has passed). The member and the second member may come into contact with each other. This phenomenon tends to occur especially in areas where the temperature changes drastically, in cold areas, and in tropical areas. In the load receiving platform elevating device of Patent Document 1, when the load receiving table is pulled out while the fall prevention member is in contact with the load receiving table, the contact of the fall prevention member is strengthened as the load receiving table is allowed to descend due to its own weight, and the device falls at the beginning of movement. There was a possibility that abnormal noise was generated due to the rubbing of the preventive member.

An object of the present invention is to provide a retractable cradle elevating device capable of suppressing the generation of abnormal noise at the start of movement when the cradle is pulled out.

In order to achieve the above object, the present invention is a retractable load receiving platform lifting device that retracts and stores the load receiving table under the vehicle frame, and moves along the guide rail attached to the lower part of the vehicle frame and the guide rail. A possible slider, an arm connecting the slider and the cradle, a lift cylinder for rotating the arm to raise and lower the cradle, and moving the cradle along with the slider along the guide rail. A slide cylinder, a hydraulic oil tank that stores hydraulic oil, a hydraulic pump that sucks and discharges hydraulic oil from the hydraulic oil tank, and an elevating control valve that controls the flow of hydraulic oil from the hydraulic pump to the lift cylinder. A slide control valve for controlling the flow of hydraulic oil from the hydraulic pump to the slide cylinder, a control device for controlling the elevating control valve and the slide control valve, and the control device from the lower side of the vehicle frame. When the loading platform is pulled out, the slide control valve is instructed to extend the slide cylinder, and at the same time, the elevating control valve is instructed to extend the lift cylinder.

According to the present invention, it is possible to suppress the generation of abnormal noise at the start of movement when the load receiving table is pulled out.

A side view showing the overall structure of a vehicle equipped with a retractable load receiving platform elevating device according to an embodiment of the present invention. A perspective view showing a detailed structure of the load receiving platform elevating device shown in FIG. Left side view showing the detailed structure of the load receiving platform elevating device shown in FIG. Cross-sectional view of the area near the left end by the IV-IV line in Fig. 3 Cross-sectional view taken along the line VV in FIG. 4 Left side view of the slider provided in the loading platform lifting device shown in FIG. Cross-sectional view taken along the line VII-VII in FIG. The figure in the state where the load receiving table of the load receiving table lifting device shown in FIG. 1 is pulled out. Top view of the fall prevention member provided in the load receiving platform elevating device shown in FIG. The rear view of the fall prevention member provided in the loading platform elevating device shown in FIG. The circuit diagram of the power unit of the load receiving platform elevating device shown in FIG. Functional block diagram of the control device and the like of the load receiving platform elevating device shown in FIG. Timing chart of loading platform withdrawal control by the control device shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings.

-Retractable loading platform lifting device-
FIG. 1 is a side view showing the overall structure of a vehicle equipped with a retractable load receiving platform elevating device according to an embodiment of the present invention. In the specification of the present application, the left and right sides of FIG. 1 are the front and rear of the vehicle.

The vehicle shown in FIG. 1 includes a vehicle frame 1, a driver's cab 2 provided in front of the vehicle frame 1, a loading platform 3 mounted on the vehicle frame 1, and a retractable loading platform elevating device provided at the lower rear portion of the vehicle frame 1. Hereinafter, it is provided with a load receiving platform elevating device) 4. For example, the load receiving platform lifting device 4 pulls the loading platform 5 into a storage position (described later) on the lower side of the folding vehicle frame 1 and stores it during traveling operation. During cargo handling work (loading and unloading of luggage with respect to the loading platform 3), the loading platform 5 is pulled out to the outside of the vehicle frame 1 (rearward in the present embodiment) and deployed, and is raised and lowered between the floor surface height and the ground height of the loading platform 3. To support cargo handling work.

FIG. 2 is a perspective view showing the detailed structure of the loading platform lifting device, FIG. 3 is a left side view, FIG. 4 is a cross-sectional view taken along the left end by lines IV-IV in FIG. 3, and FIG. It is a cross-sectional view taken along the line VV. FIG. 6 is a left side view of the slider (described later), FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6, and FIG. Is. FIG. 3 shows a state in which the power unit 26 and the operating device 27 are removed.

As shown in FIGS. 2 to 8, the load receiving platform elevating device 4 includes the above-mentioned loading platform (platform) 5 for loading luggage, a slide drive unit 6 for moving the loading platform 5 and the like in the front-rear direction, and the loading platform 5. It is provided with an elevating drive unit 7 for elevating and lowering 5. As will be described later, the load receiving table 5 slides back and forth together with the elevating drive unit 7 during deployment and storage. In the specification of the present application, the front end of the slide range of the load receiving table 5 and the elevating drive unit 7 is referred to as "front end position", the rear end is referred to as "rear end position", and the set position between the front end position and the rear end position is referred to as "intermediate position". Define. The front end position is the position at the time of storage, and the rear end position is the position at the time of cargo handling work. The intermediate position is, for example, a position about 100 mm behind the front end position. Further, as the vertical position of the load receiving table 5, the height in contact with the guide rail 8 (described later) is the "retracted height", the height in contact with the ground is the "grounding height", and the height between the stored height and the grounding height. The set height of is defined as "intermediate height". Further, when the load receiving table 5 is at the retracted height at the front end position, it is described that the load receiving table 5 is at the “storage position”, and when the load receiving table 5 is at the ground contact height at the rear end position, the loading platform 5 is “ Describe that it is in the "grounding position".

-Slide drive unit-
The slide drive unit 6 includes a pair of left and right guide rails 8, left and right sliders 9, connecting members 10, left and right bracket portions 11, support rollers 12, a support frame 13 (see FIG. 3), and a slide cylinder 14.

Two guide rails 8 extend in the front-rear direction and are arranged side by side in parallel to the left and right, and are attached to the lower rear portion of the vehicle frame 1 via the attachment portion 8a. The left and right guide rails 8 are connected at the front end by stays 8b extending to the left and right. Further, as shown in FIG. 7 and the like, the guide rail 8 has an I-shaped cross-sectional shape in which the horizontal top plate portion 8l and the bottom plate portion 8m facing vertically are connected by a vertical middle plate portion 8n.

The left and right sliders 9 include two plates 9a, an upper traveling roller 9b, a lower traveling roller 9c, and scrapers 9d and 9e, respectively. In FIGS. 5 and 8, the plate 9a on the front side is not shown in order to illustrate the internal structure of the slider 9.

The two plates 9a are members that form the main body of the slider 9, and face each other on the left and right sides of the guide rail 8, the upper traveling roller 9b, and the lower traveling roller 9c. A slight gap is interposed between the guide rail 8 and the two plates 9a sandwiching the guide rail 8.

The upper traveling roller 9b is provided so that the outer peripheral surface is brought into contact with the upper surface of the guide rail 8 and the upper surface of the guide rail 8 is rolled as the slider 9 moves. The lower traveling roller 9c is provided so that the outer peripheral surface is brought into contact with the lower surface of the guide rail 8 and the lower surface of the guide rail 8 is rolled as the slider 9 moves. That is, the slider 9 travels along the guide rail 8 by the upper traveling roller 9b and the lower traveling roller 9c sandwiching the guide rail 8 from above and below. The weight of the slider 9 and the members supported by the slider 9 is supported by the guide rail 8 via the upper traveling roller 9b and the lower traveling roller 9c, except when the load receiving table 5 or the like is in the front end position. At this time, since the slider 9 is located in front of the center of gravity of the load receiving platform elevating device 4, the upper traveling roller 9b is arranged behind the lower traveling roller 9c to support the moment. In this embodiment, the guide rail 8 is made of iron instead of aluminum so as to have sufficient strength to receive the surface pressure from the upper traveling roller 9b and the lower traveling roller 9c.

The shafts (pins) 9f of the upper traveling roller 9b and the lower traveling roller 9c have a double-sided beam structure in which both ends are supported by two plates 9a sandwiching the guide rail 8. In other words, the two plates 9a are connected by the shaft 9f. Further, a grease hole 9g (see FIG. 7) having a partial opening on the outer peripheral portion is provided inside the shaft 9f, and the plug (not shown) is removed and grease is injected from the injection port 9h with a grease gun or the like. As a result, the upper traveling roller 9b and the lower traveling roller 9c can be greased.

The scrapers 9d and 9e are provided between the two plates 9a that sandwich the guide rail 8 so as to come into contact with the surface of the guide rail 8. Specifically, the scraper 9d is bolted to the bracket 9i fixed to the plate 9a and is in contact with the upper surface of the guide rail 8. The scraper 9e is bolted to the bracket 9j fixed to the plate 9a and is in contact with the lower surface of the guide rail 8. The scrapers 9d and 9e are located in the direction of pulling out the load receiving base 5 with respect to the upper traveling roller 9b and the lower traveling roller 9c, respectively (in this example, the rear side), and precede the upper traveling roller 9b and the lower traveling roller 9c when moving backward. .. The scrapers 9d and 9e are made of, for example, rubber or resin.

The connecting member 10 is a member that connects the left and right sliders 9, and both ends of the connecting member 10 penetrate the plate 9a and project outward from the slider 9 (outside in the width direction of the machine body). The bracket portion 11 is provided at the left end of the connecting member 10. The support frame 13 extends rearward from the connecting member 10 and is located near the center between the left and right sliders 9. The support roller 12 is rotatably provided at the tip (rear end) of the support frame 13 in a posture in which the rotation axis is extended to the left and right, so that the load receiving base 5 is rotated during storage and deployment. The slide cylinder 14 is a double-acting type, and one end is fixed to the stay 8b via a bracket and the other end is fixed to the support frame 13. As the slide cylinder 14 expands and contracts, the upper traveling roller 9b and the lower traveling roller 9c roll on the guide rail 8 to travel the left and right sliders 9, and the elevating drive unit 7 moves back and forth together with the load receiving base 5. ..

Further, steps 8c and 8d (see FIG. 6 and the like) are provided on the upper surface and the lower surface of the guide rail 8, respectively. In the present embodiment, the portion of the upper surface of the guide rail 8 on the front side of the step 8c is relatively lower than the portion on the upper surface of the guide rail 8 on the rear side of the step 8c. Similarly, the portion of the lower surface of the guide rail 8 on the lower surface of the guide rail 8 on the front side of the step 8d is relatively higher than the portion on the lower surface of the guide rail 8 on the rear side of the step 8d. These steps 8c and 8d are provided at positions where the upper traveling roller 9b and the lower traveling roller 9c must overcome when the load receiving table 5 is pulled out from the front end position. Specifically, the steps 8c and 8d are provided at positions that come to the rear side of the upper traveling roller 9b and the lower traveling roller 9c, respectively, when the slider 9 is at the front end position. The term "rear side of the upper traveling roller 9b and the lower traveling roller 9c" as used herein means the rear side of the portion of the upper traveling roller 9b and the lower traveling roller 9c that is closest to the guide rail 8 (contacts the guide rail during traveling). That is, it is the lower edge portion of the upper traveling roller 9b and the upper edge portion of the lower traveling roller 9c. It is not limited to the meaning behind the trailing edge of the traveling roller.

Pressing rollers 8e (see FIG. 5 and the like) are provided below the left and right guide rails 8, respectively. The pressing roller 8e is rotatably supported on the lower surface of the guide roller 8 via the bracket 8f in a posture in which the shaft is extended to the left and right. The pressing roller 8e is arranged at the rear portion of the guide rail 8 so as to come into contact with the load receiving base 5 that rises during the retracting operation. Further, the plate 9a of the slider 9 is provided with holding plates 9l and 9m (see FIG. 5 and the like) at upper and lower positions sandwiching the guide rail 8. Pads 8g and 8h are provided on the upper surface of the guide rail 8 and the stay 8b at positions corresponding to the holding plates 9l and 9m when the load receiving base 5 is in the retracted position, respectively. The pads 8g and 8h receive the weight of the slider 9 and the elements attached to the slider 9 at the retracted position. When the load receiving base 5 is pulled into the retracted position (the slider 9 is pulled into the front end position) and the upper traveling roller 9b and the lower traveling roller 9c exceed the steps 8c and 8d, the pressing plates 9l and 9m come into contact with the pads 8g and 8h. To do. In this way, at the front end position, the slider 9 is restrained from above and below without play by sandwiching the pads 8g and 8h from above and below with the pressing plates 9l and 9m and pressing them. At this time, as described above, the distance between the upper surface and the lower surface of the guide rail 8 is shorter in the portion on the front side than the steps 8c and 8d than in the portion on the rear side. Therefore, when the slider 9 is located at the front end position and is supported by the pads 8g and 8h, the upper traveling roller 9b and the lower traveling roller 9c are separated from the upper surface and the lower surface of the guide rail 8. A roller cover 9k (FIG. 2 and the like) covering the upper side of the upper traveling roller 9b is fixed to the bracket 9i and the pressing plate 9l of the scraper 9d with bolts or the like (FIGS. 4 and 6 show the roller cover 9k removed. The state is illustrated).

The guide rail 8 is provided with a rear end sensor 15 and an intermediate sensor 16 (see FIG. 12). For the rear end sensor 15 and the intermediate sensor 16, for example, a proximity sensor or a limit switch can be used. The rear end sensor 15 is provided, for example, at the rear of the guide rail 8 so as to be located between the top plate portion 8l and the bottom plate portion 8m. A striker 9n (see FIG. 8 and the like) is provided on the inner wall surface of the plate 9a of the slider 9, and a stopper 8i is provided near the rear end of the guide rail 8. In the present embodiment, the rear end sensor 15 detects that the striker 9n is within a set distance L (for example, about 50 mm) from the stopper 8i. When the slider 9 is retracted, the striker 9n is detected by the rear end sensor 15 from a position set distance L before the position where the stopper 8i is applied. The intermediate sensor 16 detects that the slider 9 is in the intermediate position. For example, by providing a striker (not shown) on the slider 9 and providing an intermediate sensor 16 on the guide rail 8 so as to be close to the striker when the slider 9 is in the intermediate position, the slider 9 at the intermediate position can be detected.

-Elevating drive unit-
The elevating drive unit 7 includes a first arm (tilt arm) 17, a second arm (lift arm) 18, a third arm (compression arm) 19, and a lift cylinder 20 in pairs on the left and right. The upper end of the first arm 17 is rotatably connected to a bracket 10a (see FIG. 4) provided on the connecting member 10. The base end (front end) of the second arm 18 is rotatably connected to the first arm 17, and the tip (rear end) is rotatably connected to the loading platform 5. The third arm 19 has a base end portion (front end portion) rotatably connected to the bracket 10a and a tip end portion (rear end portion) rotatably connected to the load receiving base 5. The lift cylinder 20 may be a double-acting type, but in the present embodiment, it is a single-acting type, and the rod side is rotatably connected to the lower end of the first arm 17 and the bottom side is rotatably connected to the second arm 18. The second arm 18 and the third arm 19 form a parallel link that connects the load receiving base 5 to the slider 9 so as to be able to move up and down, and the parallel link is rotationally driven up and down with the expansion and contraction drive of the lift cylinder 20. The load receiving table 5 moves up and down while maintaining a horizontal posture.

− Cargo stand −
The cradle 5 includes a cradle base 21 supported by the elevating drive unit 7 and a cradle main body 23 rotatably connected to the cradle base 21 via a hinge 22. Both ends of the hinge 22 are rotatably connected to the cradle base 21 and the cradle body 23 via pins (not shown), and the rotation mechanism of the cradle body 23 with respect to the cradle base 21 is It has a double joint structure via a hinge 22. At the time of storage, the load receiving base main body 23 is folded over the upper part of the load receiving base 21 as shown in each drawing. At the connecting portion (or hinge 22) between the second arm 18 and the cradle base 21, the posture of the cradle 5 during the retracting operation is used as a value that serves as a basis for determining whether or not the cradle 5 is at an intermediate height. A gate sensor 56 (see FIG. 12) for detecting (folded state) is provided. As the gate sensor 56, an angle sensor that detects the angle of the cradle base 21 (or hinge 22) with respect to the second arm 18 (or the cradle base 21) can be used. The gate sensor 56 does not detect a predetermined angle, and a range is given to the detection angle, although it is slight. When the consignment pedestal 5 is in the set height range including the intermediate height, the entry state is entered, and it is detected that the consignment pedestal 5 is in the set height range. Alternatively, the gate sensor 56 itself simply outputs an angle detection signal, and the control device 45, which will be described later, detects that the cargo receiving platform 5 is within the set height range based on the signal of the gate sensor 56. Is also good.

-Fall prevention member-
The guide rail 8 and the cradle 5 are provided with a fall prevention member 75 (see FIG. 5 and the like) that regulates the downward movement of the cradle 5 in the retracted position and suppresses the unexpected fall of the cradle 5. .. The fall prevention member 75 includes a first member 76 (see FIG. 8) attached to the lower surface of the rear end portion of the guide rail 8 and a second member attached to the back surface (the surface facing upward when stored) of the loading platform main body 23. 77 (see FIG. 8) is provided. A plan view of the fall prevention member 75 is shown in FIG. 9, and a rear view is shown in FIG.

As shown in FIGS. 9 and 10, in the present embodiment, the first member 76 is a member having an I-shaped vertical cross section extending to the left and right, and includes a mounting portion 76a, a supporting portion 76b, and a restrained portion 76c. There is. The mounting portion 76a is a horizontal plate-shaped portion fixed to the lower surface of the guide rail 8 with bolts or the like. The restrained portion 76c is a horizontal plate-shaped member connected to the mounting portion 76a via the supporting portion 76b, and faces the lower surface of the guide rail 8 vertically via a gap with the mounting portion 76a interposed therebetween. The support portion 76b is also formed in a plate shape and runs along the vertical plane extending in the front-rear direction. The restrained portion 76c extends to at least one of the left and right sides of the supporting portion 76b, and in the present embodiment, the supporting portion 76b and the restrained portion 76c are connected in a T shape. When the first member 76 is attached to the guide rail 8 by welding or the like, the attachment portion 76a is unnecessary.

The second member 77 is attached to the back surface of the loading platform main body 23 so that the position corresponds to the first member 76 when the loading platform 5 is in the retracted position, and the mounting portion 77a, the support portion 77b, and the restraining portion 77c It has. The mounting portion 77a is a horizontal plate-shaped member having a wider area on the left and right and in front of the restraining portion 77c, and is a bolt or the like passed through a through hole (long hole in this example) 77d at each of the front and rear positions on both the left and right sides. It is fixed to the loading platform main body 23. When the second member 77 is attached to the load receiving table 5 by welding or the like, the attachment portion 77a is unnecessary. In the present embodiment, when the load receiving table 5 moves to the storage position, the above-mentioned pressing roller 8e rides on the portion of the mounting portion 77a that extends to the front side of the restraining portion 77c (see FIG. 5).

The rear portion of the mounting portion 77a is vertically bent to form an end wall 77e. The restraint portion 77c is a horizontal plate-shaped member connected to the attachment portion 77a via the left and right support portions 77b, and forms a box shape with the front side open together with the support portion 77b and the end wall 77e. The restraint portion 77c faces up and down on the back surface of the load receiving base main body 23 with the mounting portion 77a sandwiched therein through a gap, and has a slit 77f. The slit 77f extends in the front-rear direction like the guide rail 8, and a taper 77g is provided at the entrance portion (opening side, that is, the front end portion), and the entrance portion of the slit 77f is widened.

When the load receiving table 5 is in the retracted position, the support portion 76b of the first member 76 fits in the slit 77f, and at the same time, the first member is between the restraining portion 77c of the second member 77 and the back surface of the load receiving table main body 23. The restrained portion 76c of the member 76 fits in. By facing the first member 76 and the second member 77 vertically in this way, the downward movement of the stored consignment pedestal 5 is restricted. After that, the state in which the restrained portion 76c of the first member 76 is contained in the second member 77 is the "locked state" of the fall prevention member 75, and the state in which the first member 76 is disengaged from the second member 77 is the state of the fall prevention member 75. Describe as "released state". In the state where the pressing roller 8e is in contact with the load receiving base 5 (in this case, the mounting portion 77a), the restrained portion 76c of the first member 76 is attached to the restraining portion 77c of the second member 77 as shown in FIG. It is configured to face both of the portions 77a with a gap. That is, when the pressing roller 8e is in contact with the load receiving table 5, the fall prevention member 75 (first member 76 and second member 77) is in a non-contact state.

-Power unit-
As shown in FIG. 2 and the like, the power unit 26 and the operating device 27 are attached to the bracket portion 11 on the left side of the slide drive portion 6. The power unit 26 is a power device for driving the slide cylinder 14 and the lift cylinder 20. The loading platform lifting device 4 can be operated by the operating device 27.

FIG. 11 is an example of a circuit diagram of the power unit 26. The power unit 26 shown in the figure includes an electric motor 28, a hydraulic pump 29, a hydraulic oil tank 30, a supply pipe line 31, a rising control valve 32, a return pipe line 33, a lowering control valve 34, a throttle 35, and a main relief valve. It includes 36 and a conductor relay 37. The hydraulic pump 29 is driven by the electric motor 28 and discharges the hydraulic oil sucked from the hydraulic oil tank 30 to the discharge pipe line 29a. The hydraulic pump 29 and the lift cylinder 20 are connected by a supply pipe line 31, and the hydraulic oil discharged from the hydraulic pump 29 is supplied to the lift cylinder 20 via the supply pipe line 31. An ascending control valve 32 is provided in the supply pipeline 31, and the ascending control valve 32 is opened and closed by a signal input to the solenoid 32a to communicate or shut off the ascending control valve 32. The return line 33 branches from the downstream side of the ascending control valve 32 in the supply line 31 and is connected to the hydraulic oil tank 30. A lowering control valve 34 is provided in the return pipe 33, and the lowering control valve 34 is opened and closed by a signal input to the solenoid 34a to communicate or shut off the return pipe 33. In the present embodiment, the ascending control valve 32 and the ascending control valve 34 constitute an elevating control valve that controls the flow of hydraulic oil from the hydraulic pump 29 to the lift cylinder 20. An elevating control valve can also be configured with one 3-position switching valve. The throttle 35 is provided on the downstream side of the lowering control valve 34 in the return pipe 33. The diaphragm 35 is a variable diaphragm, but a fixed diaphragm may be used if the flow rate adjusting function is not required. Further, a main relief valve 36 is provided in the discharge pipe line 29a, and the maximum value of the pressure in the discharge pipe line 29a is defined by the main relief valve 36. A conductor relay 37 is provided between the electric motor 28 and the battery (not shown).

Further, the power unit 26 includes a supply pipe line 38, a throttle valve 39, a check valve 40, a supply line line 41, a pull-out control valve 42, a return line line 43, and a lead-in control valve 44. The supply pipe line 38 branches from the discharge pipe line 29a of the hydraulic pump 29 and is connected to the rod side of the slide cylinder 14. The supply line 38 is provided with a throttle valve 39 and a check valve 40. The supply pipe 41 branches from the supply pipe 38 and is connected to the bottom side of the slide cylinder 14. The outlet control valve 42 is provided in the supply pipeline 41, and the outlet control valve 42 is opened and closed by a signal input to the solenoid 42a to communicate or shut off the supply pipeline 41. The return line 43 branches off from the supply line 41 on the downstream side of the drawer control valve 42 and is connected to the hydraulic oil tank 30. A lead-in control valve 44 is provided in the return line 43, and the pull-in control valve 44 is opened and closed by a signal input to the solenoid 44a to communicate or shut off the return line 43. In the present embodiment, the withdrawal control valve 42 and the withdrawal control valve 44 constitute a slide control valve that controls the flow of hydraulic oil from the hydraulic pump 29 to the slide cylinder 14. A slide control valve can also be configured with one 3-position switching valve.

In the present embodiment, the bypass line 71 branches from the discharge line 29a at a position downstream of the main relief valve 36 and upstream of the pull-out control valve 42 and the pull-in control valve 44, and the return line. It is connected to 43. The bypass pipeline 71 is provided with a sub-relief valve 73 and a relief pressure switching valve 72. The relief pressure switching valve 72 is also a control valve similar to the raising control valve 32 and the like, and the switching position is set to the communication position (upper position in the figure) or the cutoff position (lower position in the figure) according to the command signal to the solenoid 72a. Switch to. The flow of hydraulic oil to the sub-relief valve 73 is communicated or cut off depending on the switching position of the relief pressure switching valve 72. The relief pressure switching valve 72 is provided on the upstream side of the sub-relief valve 73, but may be provided on the downstream side. The relief pressure of the sub-relief valve 73 (for example, about 6 MPa) is set lower than the relief pressure of the main relief valve 36 (for example, about 20 MPa). When the relief pressure switching valve 72 is switched to the communication position and connected to the discharge pipe line 29a, the maximum value of the pressure in the discharge pipe line 29a is defined as a value lower than the relief pressure of the main relief valve 36.

Further, the discharge line 29a of the hydraulic pump 29 is provided with a pressure sensor 74 as a pressing sensor for detecting that the load receiving base 5 is pressed against the guide rail 8 via the pressing roller 8e. When the load receiving table 5 is pressed against the guide rail 8, the pressure in the discharge line 29a rises. Therefore, when the detected value of the pressure sensor 74 exceeds the threshold value (set value), it is determined that the load receiving table 5 has come into contact with the guide rail 8. it can.

-Control device-
FIG. 12 is a functional block diagram showing a configuration example of a control device provided in the load receiving platform elevating device 4 together with peripheral devices. The control device 45 shown in FIG. 12 is provided on the vehicle side (or in the power unit 26). The control device 45 is connected to the power supply (battery) 57 of the load receiving platform elevating device 4 via the power supply switch 58, and the power supply switch 58 switches the power on / off. The power switch 58 can be installed, for example, in the driver's cab 2 of the vehicle, the power unit 26, or the like. The operation signal input to the control device 45 includes a wired signal output by the operation device 27 and a wireless signal output by a wireless operation device 46 such as a remote controller.

The operation device 27 is, for example, a pendant operation type including a push button type upper switch 47A and a lower switch 47B. The operation device 27 outputs an operation signal corresponding to the operation of the upper switch 47A or the lower switch 47B to the control device 45 via a cable or the like.

The operating device 46 includes an upper switch 48A, a lower switch 48B, a power switch 48C, and a transmission unit 49. The upper switch 48A, the lower switch 48B, and the power switch 48C are push button type switches. The transmission unit 49 generates serial data such as an ON / OFF state of the upper switch 48A or the lower switch 48B, and transmits this serial data as a wireless signal. The operating device 46 can be carried by the operator, but may be stored in the driver's cab 2 or the loading platform 3.

The control device 45 includes an input unit 50, a reception unit 51, a storage unit (memory) 52, a calculation unit (CPU) 53, an output unit 54, and a timer 55. The input unit 50 is a functional unit that inputs a detection signal from the rear end sensor 15, an intermediate sensor 16, a gate sensor 56, and a pressure sensor 74, and an operation signal from the operation device 27. The receiving unit 51 is a functional unit that receives a wireless operation signal from the operating device 46. The storage unit 52 is a circuit that stores a control program (for example, a program such as sequence control or timer control) and a control threshold value. The calculation unit 53 is a circuit that executes arithmetic processing according to a control program stored in the storage unit 52 and generates a command signal or the like instructing the operation of the cylinders 14 and 20. The output unit 54 is a circuit that appropriately outputs a command signal generated by the calculation unit 53 to the solenoids 32a, 34a, 42a, 44a, 72a and the conductor relay 37 of the control valves 32, 34, 42, 44, 72. The timer 55 is a time measuring means, and in the present embodiment, the cumulative elapsed time since the lower switch 47B or 48B is turned on during the deployment operation, the cumulative elapsed time after the gate sensor 56 is turned on during the retracting operation, and the like. It is used for the measurement of.

-Operation-
Subsequently, the operation of the load receiving platform elevating device 4 will be described. Each operation described below is under the control of the control device 45, and the command signal generated by the calculation unit 53 according to the program stored in the storage unit 52 is transmitted to the control valves 32, 34, 42 via the output unit 54. , 44, 72 and the conductor relay 37 are output.

[Cargo handling operation]
When the upper switch 47A or 48A is operated (in the state of being at the rear end position) when the load receiving table 5 is deployed, the conductor relay 37 and the conductor relay 37 from the control device 45 and A command signal is output to the ascending control valve 32. As a result, the coil 37a (FIG. 11) of the conductor relay 37 is energized, the normally open contact 37b is closed, and power is supplied from the power source 57 to the electric motor 28 via the contact 37b to drive the hydraulic pump 29. At the same time, the solenoid 32a of the ascending control valve 32 is excited, and the ascending control valve 32 switches to the opening position on the left side in FIG. At this time, since the degaussed lowering control valve 34 is at the lower shutoff position in the figure, the hydraulic oil from the hydraulic pump 29 is supplied to the lift cylinder 20 via the supply pipe line 31, and the lift cylinder 20 It extends and the consignment cradle 5 rises.

On the other hand, when the lower switch 47B or 48B is operated, a command signal is output from the control device 45 to the solenoid 34a of the lowering control valve 34 in response to the operation signal output from the operation device 27 or 46. Since the coil 37a of the conductor relay 37 is degaussed, the contact 37b opens and the electric motor 28 and the hydraulic pump 29 stop. When the solenoid 34a is excited in this state, the lowering control valve 34 is switched to the upper opening position in the figure, and the oil chamber of the lift cylinder 20 is returned to the check valve at the shutoff position of the raising control valve 32. It is connected to the hydraulic oil tank 30 via the pipeline 33, and the load receiving table 5 descends by its own weight.

In order to raise the load receiving base 5 with the slider 9 at the rear end position, the drawer control valve 42 is switched to the open position and the slider 9 is pressed against the stopper 8i while the lift cylinder 20 is extended. You may. Even when the load receiving table 5 is lowered, the hydraulic pump 29 can be driven and the drawer control valve 42 can be opened to push the slider 9 to the rear end position.

[Deployment operation]
FIG. 13 is a timing chart of the loading platform withdrawal control by the control device 45. The unfolding operation of the load receiving table lifting device 4 is an operation by sequence control for the lift cylinder 20 and the slide cylinder 14, and is an operation of moving the load receiving table 5 from the retracted position to the grounding position. As shown in the figure, the control device 45 sequentially executes the first pull-out operation, the first lowering operation, the second pulling-out operation, and the second lowering operation, and steps the loading platform 5 from the retracted position to the grounding position. Move. Specifically, the first drawer operation is an operation of pulling out the load receiving base 5 from the storage position (front end position) to the intermediate position to release the fall prevention member 75. The first lowering operation is an operation in which the load receiving table 5 pulled out to the intermediate position is lowered from the stored height to the intermediate height, and the load receiving table 5 is separated from the guide rail 8. The second withdrawal operation is an operation of pulling out the loading platform 5 from the intermediate position to the rear end position at an intermediate height. The second lowering operation is an operation of lowering the load receiving table 5 from the intermediate height to the ground contact height at the rear end position.

In FIG. 13, "upper SW" indicates on / off of the operation signal of the upper switch 47A or 48A, and "lower SW" indicates on / off of the operation signal of the lower switch 47B or 48B. “Motor” represents driving (on) and stopping (off) of the electric motor 28 and the hydraulic pump 29 by exciting and degaussing the conductor relay 37. The "gate sensor" indicates the gate sensor 56, the "intermediate sensor" indicates the intermediate sensor 16, and the "rear end sensor" indicates the on / off of the rear end sensor 15. The "control valve (top)" is the ascending control valve 32, the "control valve (bottom)" is the descending control valve 34, the "control valve (out)" is the withdrawal control valve 42, and the "control valve (on)" is. The lead-in control valve 44 and the “switching valve” represent excitation (on) and degaussing (off) of the relief pressure switching valve 72, respectively. Further, in the figure, a case where the lower switch 47B or 48B is continuously operated is illustrated. The time t2-t8 in the figure is the cumulative elapsed time of the operation time of the lower switch 47B or 48B from the time t1, and does not necessarily correspond to the elapsed time from the time t1. Under the condition that the lower switch 47B or 48B is operated intermittently, the time t2-t8 arrives with a delay by the operation interruption time. Each operation of the first withdrawal operation, the first lowering operation, the second withdrawal operation, and the second lowering operation will be described in order.

-First withdrawal operation The first withdrawal operation is performed from time t1-t4. When the loading platform 5 is in the retracted position, the gate sensor 56 and the intermediate sensor 16 are on, and the rear end sensor 15 and the pressure sensor 74 are off (time t0). The first withdrawal operation is executed only while the lower switch 47B or 48B of the operating device 27 or 46 is operated, provided that the gate sensor 56 and the intermediate sensor 16 are on and the rear end sensor 15 is off. .. Hereinafter, the case where the wireless operation device 46 is operated will be described as an example, but the operation when the wired operation device 27 is operated is also the same.

When the lower switch 48B is pressed, the control device 45 receives the conductor relay 37 and the extraction control valve 42, as well as the ascending control valve 32, the descending control valve 34, the retracting control valve 44, and the relief pressure switching valve 72 (that is, the relief pressure switching valve 72). All solenoid valves) are excited (arbitrary time t1). As a result, the hydraulic pump 29 is driven, the drawer control valve 42 is opened, the slide cylinder 14 is extended due to the difference in pressure receiving area between the rod side oil chamber and the bottom side oil chamber, and the slider 9 starts to move backward from the retracted position. At this time, the slide cylinder 14 is depressurized by opening the pull-in control valve 44 at the same time as opening the pull-out control valve 42. At the same time, the lowering control valve 34 opens, so that the contact pressure between the load receiving base 5 and the guide rail 8 (pressing roller 8e) decreases. Further, if the first member 76 and the second member 77 of the fall prevention member 75 are in contact with each other, the ascending control valve 32 is opened at the same time to release the fall prevention member 75 from the contact state. During this time, since the relief pressure switching valve 72 is also open, the contact pressure between the load receiving base 5 and the guide rail 8 (pressing roller 8e) does not rise more than necessary.

The set time (t1-t2) for opening the pull-in control valve 44 at the time of starting is, for example, about 0.2 s, and the pull-in control valve 44 is degaussed and closed at time t2. Further, the set time (t1-t3) for opening the ascending control valve 32, the descending control valve 34 and the relief pressure switching valve 72 is, for example, about 1 s, and the ascending control valve 32, the descending control valve 34 and the lowering control valve 34 are opened at time t3. The relief pressure switching valve 72 is also degaussed and closed. In the present embodiment, the pull-out control valve 42 and the pull-out control valve 42 are temporarily closed (time t2) in the middle of the first pull-out operation, and the ascending control valve 32, the descending control valve 34, and the relief pressure switching valve 72 are closed. At the same time, the drawer control valve 42 opens again (time t3). As described above, the drawer control valve 42 opens for a moment to release the pressure of the slide cylinder 14 at the time of initial movement, but by closing it once at time t2, the contact pressure between the load receiving base 5 and the guide rail 8 is suppressed, and the fall prevention member 75 Avoidance of the contact state is prioritized only for the set time up to time t3.

During the first extraction operation, the conductor relay 37 is constantly excited, and after time t3, the control device 45 excites the conductor relay 37 and the extraction control valve 42, and degausses the control valves 32, 34, 44, 72. The consignment pedestal 5 is moved backward in this state. After that, when the slider 9 moves backward and the intermediate sensor 16 is turned off (time t4), the control device 45 ends the first withdrawal operation. Since the time t4 is the time when the intermediate sensor 16 is turned off, the time t3-t4 can change if the reverse speed of the slider 9 changes depending on the viscosity of the hydraulic oil or the like.

In the present embodiment, when the control valves 32, 34, 44 are closed, the drawer control valve 42 is opened, and the hydraulic oil (total amount in this example) discharged by the hydraulic pump 29 is supplied to the slide cylinder 14, the slide cylinder 14 The extension speed is described as "first speed".

-First descending operation The first descending operation is performed over time t4-t5. The first lowering operation is executed only while the lower switch 48B is operated, provided that the gate sensor 56 is on and the intermediate sensor 16 and the rear end sensor 15 are off. When the slider 9 moves backward and the intermediate sensor 16 is turned off (time t4), the control device 45 excites the lowering control valve 34 and degausses the conductor relay 37 and the control valves 32, 42, 44, 72. Switch. As a result, the hydraulic pump 29 is stopped, the hydraulic oil in the oil chamber of the lift cylinder 20 is discharged to the hydraulic oil tank 30, and the load receiving table 5 is lowered by its own weight. When the load receiving table 5 is lowered and the gate sensor 56 is turned off (time t5), the control device 45 ends the first lowering operation. Since the time t5 is the time when the gate sensor 56 is turned off, the time t4-t5 may change if the descending speed of the cradle 5 changes depending on the viscosity of the hydraulic oil or the like.

-Second withdrawal operation The second withdrawal operation is performed from time t5-t7 in FIG. The second pull-out operation is that the gate sensor 56, the intermediate sensor 16 and the rear end sensor 15 are off, or that only the rear end sensor 15 is turned on from the state where these three sensors are off and within the set time. Is executed on condition. The second withdrawal operation is also executed only while the lower switch 48B is operated during the time t5-t6. If the operation of the lower switch 48B is interrupted during the time t5-t6, the withdrawal operation is also interrupted. On the other hand, during time t6-t7, that is, until the rear end sensor 15 is turned on and the set time elapses, the pull-out operation is forcibly and continuously executed regardless of whether or not the lower switch 48B is operated. To. The set time for the elapsed time after the rear end sensor 15 is turned on is the time required to pull out the consignment pedestal 5 by the set distance L at the second speed (described later), or a slight margin time is added to this. It's time.

When the load receiving table 5 is lowered and the gate sensor 56 is turned off (time t5), the control device 45 excites the conductor relay 37 and the extraction control valve 42, and degausses the control valves 32, 34, 44, 72. Switch to. As a result, the loading platform 5 moves backward at the first speed. Since the rear end sensor 15 is arranged as described above, the rear end sensor 15 is turned on during the second pull-out operation (when the distance between the striker 9n of the slider 9 and the stopper 8i becomes the set distance L or less). (Time t6). When the rear end sensor 15 is turned on and the distance between the stopper 8i and the slider 9 becomes less than the set distance L, the control device 45 excites the conductor relay 37 and the control valves 34 and 42 to control the control valve 32. , 44, 72 are demagnetized, and the reverse speed is reduced from the first speed to the second speed. The reverse operation of the second speed slider 9 is continuously executed for the set time regardless of whether or not the lower switch 48B is operated (even if the operation of the lower switch 48B is interrupted), and the load receiving table 5 is forced to operate at the second speed. It is pulled out to the rear end position. When the set time elapses after the rear end sensor 15 is turned on (at time t7), the second withdrawal operation ends.

The above "second speed" is a slide when the control valves 32 and 44 are closed, the control valves 34 and 42 are opened, and the hydraulic oil discharged by the hydraulic pump 29 is divided into the slide cylinder 14 and the hydraulic oil tank 30. This is the extension speed of the cylinder 14. Compared to the first speed at which the hydraulic oil is not returned to the hydraulic oil tank 30 via the lowering control valve 34, the second speed of some hydraulic oil is slowed down to the hydraulic oil tank 30 via the lowering control valve 34. .. Further, since the time t6 is the time when the rear end sensor 15 is turned on, the time at the time t5-t6 can change if the reverse speed of the slider 9 changes depending on the viscosity of the hydraulic oil or the like. For the set time (time t6-t7) after the rear end sensor 15 is turned on, the slider 9 moves backward by the set distance L even if the second speed decreases in consideration of various conditions such as the viscosity of the hydraulic oil. The minimum required time is set.

-Second descent operation The second descent operation is performed over time t7-t8. In the second lowering operation, the lower switch 48B is operated on condition that the set time has elapsed since the gate sensor 56 and the intermediate sensor 16 were turned off and the rear end sensor 15 was turned on (after the time t7). It is executed only while it is. When the set time elapses after the slider 9 moves backward and the rear end sensor 15 is turned on (time t7), the control device 45 excites the lowering control valve 34, and the conductor relay 37 and the control valves 32, 42, 44 , 72 are switched to the degaussed state. As a result, the hydraulic pump 29 is stopped, the hydraulic oil in the oil chamber of the lift cylinder 20 is discharged to the hydraulic oil tank 30, and the load receiving table 5 is lowered by its own weight. When the operation of the lower switch 48B is stopped after confirming that the load receiving table 5 is grounded, the operation signal is turned off (time t8). When the operation signal is turned off, the control device 45 ends the second lowering operation and switches the conductor relay 37 and the control valves 32, 34, 42, 44, 72 to the degaussed state. After that, the operator expands and deploys the consignment cradle 5. As a result, the deployment of the cargo receiving table 5 is completed, and the above-mentioned cargo handling operation can be performed by operating the operating device 27 or 46.

[Storage operation]
The retracting operation of the load receiving platform lifting device 4 is an operation of sequence control of the control device 45 for the lift cylinder 20 and the slide cylinder 14, and is an operation of moving the load receiving platform 5 from the ground contact position to the storage position. Although not particularly shown, the storage operation of the present embodiment includes a first ascending operation, a first retracting operation, a second ascending operation, and a second retracting operation, and moves the cradle 5 in a step-like manner in the same manner as the unfolding operation. For example, in the first ascending operation, the upper switch 48A is operated with the load receiving base 5 folded and leaning against the support roller 12 on the condition that the rear end sensor 15 is on and the intermediate sensor 16 and the gate sensor 56 are off. Is executed. When the load receiving table 5 is expanded, the load receiving table 5 exceeds the storage height and reaches the height of the floor surface of the loading platform 3, but when the load receiving table 5 is leaned against the support roller 12, the load receiving table 5 has a storage height. The gate sensor 56 is turned on when the intermediate height is reached before reaching. This triggers the switching from the first ascending operation to the first retracting operation, and eventually the execution of the retracting operation.

The first retracting operation is started on the condition that the rear end sensor 15 and the gate sensor 56 are turned on and the intermediate sensor 16 is turned off, and is executed until the slider 9 advances and the intermediate sensor 16 is turned on. The second ascending operation is started on the condition that the intermediate sensor 16 and the gate sensor 56 are turned on and the rear end sensor 15 is turned off, until the detected value of the pressure sensor 74 exceeds the threshold value (the cradle 5 is the guide rail 8). Is executed (until it is pressed against). During the second ascending operation, the control device 45 opens the relief pressure switching valve 72 at the same time as the ascending control valve 32, and lowers the relief pressure of the circuit to the specified pressure by the sub-relief valve 73, thereby causing the load receiving base 5 and the guide rail 8. Suppress the contact pressure acting between.

When it is recognized that the load receiving base 5 has come into contact with the guide rail 8 based on the signal of the pressure sensor 74, the control device 45 switches the operation from the second ascending operation to the second retracting operation. The second retracting operation is an operation automatically commanded by the control device 45, and the retracting control valve 44 opens and the slider 9 advances regardless of whether or not the operating device 27 or 46 is operated. This is to ensure that the loading platform 5 reaches the storage position. At this time, the relief pressure switching valve 72 is closed with a slight delay (for example, 500 ms) from the time when the pull-in control valve 44 is opened, and the relief pressure of the hydraulic circuit is returned to the relief pressure of the main relief valve 36. This is to weaken the contact pressure of the load receiving base 5 with respect to the guide rail 8 at the start of the second pull-in operation. When the controller 45 advances the slider 9 by the set time, the control device 45 closes the pull-in control valve 44, completes the second pull-in operation, and ends the retracting operation. The set time for this pull-in operation is the minimum time required for the slider 9 to move from the intermediate position to the storage position in consideration of the fluctuation of the viscosity of the hydraulic oil. After the storage operation is completed, the conductor relay 37 and the control valves 32, 34, 42, 44, 72 are all degaussed.

-Effect-
(1) As described above, when the control device 45 pulls out the load receiving base 5 from the lower side of the vehicle frame 1, the slide control valve is instructed to extend the slide cylinder 14, and at the same time, the elevating control valve is extended to the lift cylinder 20. Is configured to command. That is, the pull-out control valve 42 opens and the ascending control valve 32 opens at the same time, so that the first member 76 and the second member 77 of the fall prevention member 75 are in contact with each other as time elapses after storage. Then, you can get out of this state. Therefore, it is possible to suppress the generation of abnormal noise due to the rubbing of the first member 76 and the second member 77 of the fall prevention member 75 at the start of movement when the load receiving table 5 is pulled out. During this time, the initial movement can be facilitated by suppressing the contact pressure between the load receiving table 5 and the guide rail 8.

Further, if there is an individual difference in the facing distance between the first member 76 and the second member 77 of the fall prevention member 75, the first member 76 and the second member 77 may or may not come into contact with each other even if the hydraulic oil leaks to the same extent. To do. In other words, even under the same usage conditions, there is a possibility that abnormal noise may or may not occur at the initial movement of the pull-out operation depending on the product (individual). In the case of the present embodiment, the above-mentioned action suppresses the generation of abnormal noise at the initial movement of the pull-out operation regardless of individual differences, and the pull-out operation can be smoothly executed. In this way, it is possible to suppress variations in product quality.

(2) When the control device 45 pulls out the load receiving base 5 from the lower side of the vehicle frame 1, the slide control valve is instructed to extend the slide cylinder 14, and at the same time, the elevating control valve is instructed to contract the lift cylinder 20. It is configured in. That is, in the present embodiment, both the expansion and contraction of the lift cylinder 20 are commanded at the initial movement of the first pull-out operation. By opening the lowering control valve 34 at the same time as the drawer control valve 42 opens, if the contact pressure between the load receiving base 5 and the guide rail 8 remains at the value at the time of the retracting operation, this can be reduced.

However, as long as the above basic effect (1) is obtained, it is not necessary to open the lowering control valve 34 at the initial operation of the first withdrawal operation.

(3) The control device 45 is configured to instruct the elevating control valve to extend the lift cylinder 20 and at the same time to instruct the relief pressure switching valve 72 to open. When the ascending control valve 32 opens, the load receiving base 5 is pressed against the guide rail 8, but since the descending control valve 34 is open, the contact pressure with the guide rail 8 does not increase more than necessary. In addition, by opening the relief pressure switching valve 72, even if the contact pressure between the load receiving base 5 and the guide rail 8 rises for some reason, the maximum pressure of the circuit is limited by the relief pressure of the sub-relief valve 73, and the load is received. The contact pressure between the base 5 and the guide rail 8 is also suppressed to less than that.

However, as long as the above basic effect (1) is obtained, it is not always necessary to control the relief pressure switching valve 72 to be opened during the first withdrawal operation.

(4) Further, the control device 45 commands the slide control valve to extend the slide cylinder 14 at time t1, and then during time t2-t3, both the ascending control valve 32 valve and the descending control valve 34 The command for the extension operation of the slide cylinder 14 is stopped while the opening command for the slide cylinder 14 is continued. As described above, the drawer control valve 42 opens for a moment to release the pressure of the slide cylinder 14 at the time of initial movement, but by closing it once during time t2-t3, the contact pressure between the load receiving base 5 and the guide rail 8 is suppressed and the slide cylinder 8 is prevented from falling. Avoidance of the contact state of the member 75 is first executed. Waiting for the effect of suppressing the contact pressure to occur in this way, at time t3, both the ascending control valve 32 and the descending control valve 34 are closed, and at the same time, the extension operation of the slide cylinder 14 is commanded again. The pull-out operation can be executed smoothly while surely suppressing the generation of abnormal noise.

However, as long as the above basic effect (1) is obtained, it is not always necessary to control the pull-out control valve 42 to be temporarily closed during the first pull-out operation.

(5) Further, a throttle 35 is provided in the return pipe 33 of the circuit of the lift cylinder 20 so as to be located on the downstream side of the lowering control valve 34. When the ascending control valve 32 and the descending control valve 34 are opened at the same time, a pressure sufficient for the throttle 35 acts on the oil chamber of the lift cylinder 20. As a result, a pressure that allows the lift cylinder 20 to extend against its own weight can be applied to the oil chamber of the lift cylinder 20.

However, a part of hydraulic oil is supplied to the lift cylinder 20 when the lowering control valve 34 and the ascending control valve 32 are opened at the same time because the flow path area of the return pipe 33 is smaller than that of the supply pipe 31. As far as possible, the aperture 35 is not always necessary.

(6) Further, since the load receiving table 5 is pressed against the guide rail 8 via the pressing roller 8e, friction does not occur between the sliding load receiving table 5 and the guide rail 8. Therefore, even if the load receiving table 5 is pressed against the guide rail 8 and slid, no abnormal noise due to rubbing between the load receiving table 5 and the guide rail 8 is generated. Further, the fall prevention member 75 is in a non-contact state when the load receiving base 5 is pressed against the guide rail 8 via the pressing roller 8e. As a result, by pressing the load receiving base 5 against the guide rail 8 and sliding it, the rubbing of the fall prevention member 75 can be appropriately avoided without variation. This configuration is extremely advantageous in suppressing the generation of abnormal noise during the initial movement of the pull-out operation.

However, in order to suppress friction between the sliding load receiving table 5 and the guide rail 8, the load receiving table 5 may be pressed against the guide rail 8 via, for example, a resin pad having a small friction coefficient. Further, as long as the contact pressure between the first member 76 and the second member 77 of the fall prevention member 75 is weakened to suppress strong rubbing between the two members, the ascending control valve 32 is opened and the first member 76 is the second member 77. Just move away from. In that sense, it is not always necessary to slide with the load receiving base 5 pressed against the guide rail 8.

-Modification example-
In the present embodiment, the case where the load receiving table 5 is moved from the storage position to the installation position by the procedure of the first pull-out operation, the first lowering operation, the second pulling-out operation, and the second lowering operation has been described as an example. The number of executions of the pull-out operation and the lowering operation during this expansion operation may be changed. The same applies to the storage operation. Due to the structure, the first of the unfolding operations is inevitably the withdrawal operation. Controls are applicable and similar effects can be obtained.

Further, although an angle sensor is applied to the gate sensor 56 to detect that the load receiving table 5 is at an intermediate height based on the angle change of the load receiving table main body 23, a proximity sensor can be used instead. .. Further, when visually confirming that the slider 9 is at the rear end position, the rear end sensor 15 can be omitted. Further, although the case where the control that the load receiving platform elevating device 4 operates regardless of the presence or absence of the operation such as the pull-out operation at the time t6-t7 is adopted as an example has been described as an example, it is raised during the retracting operation and the deploying operation. The load receiving platform elevating device 4 may be operated only while the operation or the lowering operation is performed. Further, the operating device 27 or 46 may be provided with a stop switch 47D or 48D (see FIG. 12) so that a forced operation sequence such as a withdrawal operation at time t6-t7 can be manually stopped. Further, in order to raise and lower the load receiving table 5 while the slider 9 is reliably located at the rear end position, the drawer control valve 42 is operated during execution of the cargo handling operation, the second lowering operation of the unfolding operation, and the first ascending operation of the retracting operation. The stopper 8i and the striker 9n can be pressed against each other so as to switch to the communication position. The present invention is also applicable in these cases, and the same effects as described above can be obtained.

Further, in the present embodiment, the case where the retractable cradle elevating device for storing the cradle under the vehicle frame is applied is described as an example. However, there are some retractable load receiving platform elevating devices of this type that can select a storage position in which the loading platform is raised at the rear of the loading platform in addition to a storage position in which the loading platform is stored under the vehicle frame. Even if the present invention is applied to a retractable load receiving platform elevating device that employs such two storage postures, the same effect can be obtained when the load receiving platform is pulled out from the lower side of the vehicle frame.

Further, the case where the present invention is applied to the retractable cradle elevating device for carrying out cargo handling work by pulling the cradle 5 to the rear side of the vehicle has been described as an example, but the cradle is pulled out to the left or right side of the vehicle. The same effect can be obtained by applying the present invention to a retractable cargo receiving platform elevating device that performs cargo handling work. In addition, the configuration in which the slider 9 travels on the guide rail 8 with rollers has been described as an example, but the slider is supported by the pad with respect to the rail, and the pad is slid with respect to the rail to slide the slider. There is also a loading platform lifting device to move. Of course, the present invention can be applied to such a load receiving platform elevating device.

1 ... Vehicle frame, 4 ... Retractable load receiving platform lifting device, 5 ... Loading platform, 8 ... Guide rail, 8e ... Pressing roller, 9 ... Slider, 14 ... Slide cylinder, 17 ... 1st arm (arm), 18 ... 2nd Arm (arm), 19 ... 3rd arm (arm), 20 ... lift cylinder, 29 ... hydraulic pump, 29a ... discharge pipeline, 30 ... hydraulic oil tank, 31 ... supply pipeline, 32 ... lift control valve (elevation) Control valve), 33 ... Return pipeline, 34 ... Lowering control valve (elevating control valve), 36 ... Main relief valve, 42 ... Pull-out control valve (slide control valve), 44 ... Pull-in control valve (slide control valve) ), 45 ... Control device, 71 ... Bypass pipeline, 72 ... Relief pressure switching valve, 73 ... Sub-relief valve, 75 ... Fall prevention member, 76 ... First member, 77 ... Second member

Claims (6)

In a retractable cradle elevating device that retracts the cradle by pulling it under the vehicle frame.
The guide rail attached to the bottom of the car frame and
A slider that can be moved along the guide rail,
An arm connecting the slider and the cradle,
A lift cylinder that rotates the arm to raise and lower the loading platform,
A slide cylinder that moves the cradle together with the slider along the guide rail,
A hydraulic oil tank that stores hydraulic oil and
A hydraulic pump that sucks and discharges hydraulic oil from the hydraulic oil tank,
An elevating control valve that controls the flow of hydraulic oil from the hydraulic pump to the lift cylinder,
A slide control valve that controls the flow of hydraulic oil from the hydraulic pump to the slide cylinder,
A control device for controlling the elevating control valve and the slide control valve is provided.
When the control device pulls out the loading platform from the lower side of the vehicle frame, the control device commands the slide control valve to extend the slide cylinder and at the same time commands the elevating control valve to extend the lift cylinder. A featured retractable cradle lifter. In the retractable cargo receiving platform elevating device according to claim 1.
The main relief valve that defines the maximum value of the pressure in the discharge line of the hydraulic pump,
A bypass line that branches off from the discharge line and connects to the hydraulic oil tank,
A sub-relief valve provided in the bypass pipeline and having a lower relief pressure than the main relief valve,
It is equipped with a relief pressure switching valve provided in the bypass pipeline.
The control device is a retractable load receiving platform elevating device, characterized in that the elevating control valve is instructed to extend the lift cylinder, and at the same time, the relief pressure switching valve is instructed to open. In the retractable cargo receiving platform elevating device according to claim 1 or 2.
After instructing the slide control valve to extend the slide cylinder, the control device stops the command for the extension operation of the slide cylinder while continuing the command for the extension operation of the lift cylinder, and then stops the command for the extension operation of the lift cylinder. A retractable load receiving platform elevating device characterized in that at the same time as instructing the stop of the extension operation, the extension operation of the slide cylinder is instructed again. In the retractable load receiving platform elevating device according to any one of claims 1-3.
The lift cylinder is a single-acting type and
The elevating control valve is a rise control valve provided in a supply pipeline connecting the hydraulic pump and the lift cylinder, and the lift control valve in the flow direction of hydraulic oil returning from the lift cylinder to the hydraulic oil tank . It includes a lowering control valve provided in the return pipeline that branches off from the supply pipeline at the downstream position and connects to the hydraulic oil tank.
The control device is a retractable cradle elevating device, characterized in that the slide control valve is instructed to extend the slide cylinder, and at the same time, both the ascending control valve and the descending control valve are instructed to open. The retractable load receiving platform elevating device according to claim 4, wherein the return pipeline is provided with a throttle on the downstream side of the lowering control valve. In the retractable load receiving platform elevating device according to any one of claims 1-5.
It has a first member provided on the guide rail and a second member provided on the cradle, and the first member and the second member face each other up and down so that the cradle is moved downward. Fall prevention members that regulate movement and
A pressing roller provided at the lower part of the guide rail and in contact with the stored loading platform is provided.
A retractable cradle elevating device, characterized in that the first member and the second member are in a non-contact state when the pressing roller is in contact with the cradle.

Images