JP4159192B2 - Cabylt equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cabbutylt device mounted on a cabover engine type automobile, and more particularly, to a carbilt device for tilting a cab by a cylinder device, and to which a cab lowering prevention device for preventing the cab from descending is attached. About.
[0002]
[Prior art]
In general, in a cab-over type automobile, the maintenance and inspection of the engine portion can be easily performed by lifting and tilting the cab. In such a case, there is a case where a cab tilt device is used in which a tilt cylinder device is interposed between the cab and the frame, and the cab tilt operation is performed by the expansion and contraction operation of the tilt cylinder device. .
[0003]
That is, in the tilt cylinder device of the cabylt device, the upper end of the piston rod is pivotally attached to the cab via the link, and the lower end of the cylinder is pivotally attached to the frame. The hydraulic drive circuit of the cylinder device for tilting is driven by a raising side supply / discharge oil passage (hereinafter referred to as a raising side oil passage), a lowering side supply / discharge oil passage (hereinafter referred to as a lower side oil passage), and a motor. A pump, a tank, and a manual switching valve (hereinafter referred to as a switching valve) are provided. The raising side oil passage is fluidly connected to a frame side hydraulic chamber (hereinafter referred to as a raising side hydraulic chamber) of the cylinder, and the lowering side oil passage is referred to as a cab side hydraulic chamber (hereinafter referred to as a lowering side hydraulic chamber). ) Fluidly connected.
[0004]
In the conventional cabylt device, in order to prevent the cab from descending when a failure occurs in the raising side oil passage of the tilt cylinder device, a pilot operated check valve is provided in the raising side oil passage. It is installed. The pilot operated check valve prevents the piston of the tilt cylinder device from being pushed down by the weight of the cab by preventing the flow from the raising side hydraulic chamber toward the switching valve. On the other hand, when pressure oil is supplied to the lower side hydraulic chamber of the tilt cylinder device and the cab is lowered, it is necessary to discharge the pressure oil in the upper side hydraulic chamber. By opening the check valve using the pressure in the oil passage as a pilot pressure, the pressure oil in the raising side hydraulic chamber is discharged.
[0005]
[Problems to be solved by the invention]
In the meantime, as shown in FIG. 2, when a release cylinder device that automatically releases the engagement between the cab lowering prevention member and the stay is provided, the raising side oil is operated after the release cylinder device is operated. It is necessary to open the pilot operated check valve on the road, and in order to meet this requirement, the valve opening pressure (pilot pressure) of the pilot operated check valve needs to be set high. However, in this conventional pilot operated check valve of this type, it is difficult to set the pilot pressure high because the spring load of the spring has already reached its limit due to space saving.
[0006]
An object of the present invention is to provide a cabylt device that can open a pilot-operated check valve in an upward oil passage after a release cylinder device is operated without setting a spring load of the spring high.
[0007]
[Means for Solving the Problems]
According to a first aspect of the present invention, a cab lowering device is assembled to a tilting cylinder device that is interposed between a cab and a frame and tilts the cab. In a cabylt device comprising: a stay pivotally attached to a piston rod of a tilt cylinder device; and a descending prevention member fixed to a cylinder of the tilt cylinder device and engaged with the stay.
A release cylinder device for releasing the engagement of the lowering prevention member with the stay is installed in a cylinder of the tilt cylinder device, and a cylinder chamber of the release cylinder device is provided on the lower side supply / discharge of the tilt cylinder device. Connected to an oil passage and a pilot passage of a pilot operated check valve interposed in the raising side supply / discharge oil passage of the tilt cylinder device,
The pilot operated check valve has a valve port formed between a primary port and a secondary port, a valve seat formed around the valve port, and a seat on and off the valve seat to open and close the valve port. And a cylinder chamber formed adjacent to the valve opening and connected to the pilot passage, and a pilot piston mounted in the cylinder chamber and having a piston rod facing the valve body. Since the effective pressure receiving area of the pilot piston is set to be small, the pilot pressure of the pilot operated check valve is set to be high.
[0008]
Claims of the invention 1 The carbitol device according to further, The cylinder chamber is formed with at least two chambers, a large-diameter chamber to which the pilot passage is connected and a small-diameter chamber adjacent to the large-diameter chamber, and the pilot piston is disposed in the large-diameter chamber. The large-diameter portion and the small-diameter portion connected to the large-diameter portion and disposed in the small-diameter chamber are configured by at least two portions, and the area of the small-diameter portion is set to the effective pressure receiving area of the pilot piston. It is characterized by.
[0009]
Claims of the invention 2 The carbylating device according to the present invention is characterized in that a sleeve in which a small diameter portion of the pilot piston is slidably fitted is fitted in the small diameter chamber of the cylinder chamber.
[0010]
Claims of the invention 3 The cabylt device according to the present invention is characterized in that the pilot operated check valve is disposed at one end of a cylinder of the tilt cylinder device.
[0011]
According to the first means described above, since the pilot pressure of the pilot operated check valve is set high, the pilot operated check valve in the raising side oil passage is opened after the release cylinder device is operated. Can do. Moreover, since the pilot pressure of the pilot operated check valve is set high because the effective pressure receiving area of the pilot piston is set small, the spring load of the spring is set high, for example, by increasing the dimensions of the spring. You don't have to.
[0012]
According to the second means described above, since the portion excluding the small diameter portion which is the effective pressure receiving area portion can be exposed to the large diameter chamber and the valve opening of the cylinder chamber, the spring and the piston rod should be rationally arranged. Can do.
[0013]
According to the third means described above, since the effective pressure receiving area can be set very small by inserting the effective pressure receiving area portion into the sleeve, the pilot pressure of the pilot operated check valve can be set very high. it can. Further, since the sleeve can be absorbed by the acting force due to the pressure of the primary port, the acting force can be absorbed, so that the seal structure can be simplified.
[0014]
According to the fourth means described above, since the pilot operated check valve can be integrally incorporated in the cylinder of the tilt cylinder device, the handleability and versatility of the tilt cylinder device as a whole can be improved. .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0016]
As shown in FIG. 1, the cabylt device according to the present embodiment includes a tilt cylinder device 3 that is interposed between the cab 1 and the frame 2 and that tilts the cab 1 by an expansion and contraction operation. That is, the cab 1 is supported by the frame 2 so as to be rotatable in the front-rear direction by a fulcrum 1a, and the upper end of the piston rod 4 of the tilt cylinder device 3 is pivotally attached to the cab 1 via a link. The lower end of the cylinder 5 is pivotally attached to the frame 2.
[0017]
As shown in FIG. 2, the hydraulic drive circuit 10 of the tilt cylinder device 3 includes a raising-side supply / discharge oil passage (hereinafter, referred to as a raising-side oil passage) 11 and a lower-side supply / discharge oil passage (hereinafter, referred to as “upward-side supply / discharge oil passage”). (Referred to as a lower oil passage) 12, a pump 13 driven by the motor 8, a tank 14, and a manual switching valve (hereinafter referred to as a switching valve) 15. The raising side oil passage 11 is fluidly connected to a frame side hydraulic chamber (hereinafter referred to as raising side hydraulic chamber) 5 a of the cylinder 5, and the lowering side oil passage 12 is connected to the cab side hydraulic chamber (hereinafter referred to as lowering portion) of the cylinder 5. Side hydraulic chamber) fluidly connected to 5b.
[0018]
The switching valve 15 is configured as a four-port / two-position / manually operated switching valve. In normal operation, the load port a of the raising side oil passage 11 is set to the tank port T and the loading port b of the lowering side oil passage 12 is set. Are connected to the pump port P, and at the time of switching, the load port a of the upside oil passage 11 is connected to the pump port P, and the load port b of the downside oil passage 12 is connected to the tank port T. ing. A pilot-operated check valve (hereinafter referred to as a pilot check valve) 16 according to the present embodiment is interposed in the raising side oil passage 11, and the pilot check valve 16 has a pilot pressure whose hydraulic pressure is set in advance. When the pressure is less than the value, the flow from the cylinder 5 side to the switching valve 15 side is blocked, and when the pressure exceeds the pilot pressure value, the flow is allowed. In FIG. 2, 7 is an emergency manual pump, 9 is a relief valve, 17 is a throttle, 18 is a filter, and 19 is a check valve.
[0019]
As shown in FIG. 3, the cab lowering device is provided with a cab lowering prevention device 20 constituted by a stay and a lowering prevention member. That is, the stay 21 is formed in a long channel steel rod using a rigid metal material, and the upper end is pivotally attached to the upper end of the piston rod 4 of the tilt cylinder device 3. A plurality of teeth 22 are formed in a sawtooth shape at the intermediate portion at the opening side end of the stay 21. The teeth 22 are formed in a substantially semi-trapezoidal shape in which the lower side (frame side) is inclined and the upper side (cab side) is substantially perpendicular to the end side.
[0020]
A region of the outer peripheral surface of the cylinder 5 facing the stay 21 is covered and fixed with a protective cover 23 made of resin, and the protective cover 23 prevents the stay 21 and the cylinder 5 from rubbing against each other. It is like that. A channel-shaped yoke 24 is fixed to the cab side end of the cylinder 5 so as to straddle the cylinder 5. An appropriate clearance is provided between the inner surface of the yoke 24 and the protective cover 23 so as to allow the free end portion of the stay 21 to slide smoothly.
[0021]
As shown in FIGS. 3 and 4, a notch portion 25 for visually confirming that the teeth of the stay 21 and the claw portion 27 of the descending prevention member 26 are engaged with each other at the opening end side of the yoke 24. The channel-shaped steel-shaped descent prevention member 26 is disposed so as to face the notch 25. The lowering prevention member 26 is pivotally supported by a pin 28 in a state where the lowering prevention member 26 is fixed at a position opposite to the yoke 24 on the outer periphery of the cylinder 5 and straddles a cylinder block 31 of a release cylinder device 30 described later. A claw portion 27 that meshes with the lower end surface of the stay 21 and the teeth 22 is formed on the opening end side that is the free end portion of the descending prevention member 26. The lowering prevention member 26 is provided with a locking portion 26a, and the yoke 24 is provided with a locking portion 24a. Between the locking portion 26a of the lowering prevention member 26 and the locking portion 24a of the yoke 24, The tension spring 29 is stretched in a power storage state. The tension spring 29 constantly urges the tension force in the direction in which the claw portion 27 of the descending prevention member 26 presses against the opening end side of the stay 21.
[0022]
As shown in FIGS. 5 and 6, a release cylinder device 30 for automatically releasing the lowering prevention member 26 is installed at a position opposite to the yoke 24 of the cylinder 5. That is, the release cylinder device 30 includes a cylinder block 31, and one main surface of the cylinder block 31 is fixed to the outer peripheral surface of the cylinder 5 of the tilt cylinder device 3.
[0023]
A cylinder chamber 32 is opened at the cab side end of the cylinder block 31 so as to extend radially outward with respect to the cylinder 5, and a cylinder head is formed at the opening of the cylinder chamber 32 on the side opposite to the cylinder 5. 33 is screwed. The rear end portion of the plunger 34 is accommodated in the cylinder chamber 32, the intermediate portion of the plunger 34 is slidably supported by the cylinder head 33, and the push portion 35 at the front end portion is connected to the cylinder 5 from the cylinder chamber 32. It protrudes in the opposite direction and faces the facing surface of the lowering prevention member 26. A return spring 36 is interposed between the cylinder head 33 and the plunger 34 so as to constantly urge the plunger 34 in the direction in which the plunger 34 is pulled into the cylinder chamber 32.
[0024]
A release oil passage 37 communicating with the cylinder chamber 32 is formed in the cylinder block 31. As shown in FIG. 2, the release oil passage 37 constitutes a part of the lower oil passage 12 and is connected to the load port b of the lower oil passage 12 of the switching valve 15. The cylinder chamber 32 is connected to one end of a communication oil passage 38 constituting a part of the lower oil passage 12, and the other end of the communication oil passage 38 is a lower oil pressure of the cylinder 5 of the tilt cylinder device 3. It is connected to the chamber 5b. A constriction 39 for restricting the flow of pressure oil is formed at the connecting portion of the communication oil passage 38 of the cylinder 5.
[0025]
FIG. 7 is an electric circuit diagram of the motor 8 that drives the pump of the cabylt device, and shows a state in which the motor can run. As shown in FIG. 7, a control circuit 83 is interposed in the drive circuit 80 of the motor 8. That is, the switch 84a of the relay 84 of the control circuit 83 is provided in the middle of the drive circuit 80 in which the motor 8 and the power supply 81 are connected via the fuse 82, and the cab lock switch 85 is provided in the coil 84b of the relay 84. A stroke switch 86, a switching valve switch 87, a cab stopper switch 88, a transmission neutral detection switch (hereinafter referred to as neutral switch) 89, a thermal switch 90, a pump switch 91, a buzzer 92, and a fuse 93. And are connected.
[0026]
The cab switch 85 is arranged in a cab block device 94 (see FIG. 1) for locking the tilted cab, and detects that the cab 1 is locked by the cab block device 94. . As shown in FIG. 7, the cab lock switch 85 includes a fixed contact 85 a, a first contact 85 b, a second contact 85 c, and a movable iron piece 85 d, and the fixed contact 85 a is connected to the drive circuit 80 via a fuse 93. The first contact 85 b is connected to the switching valve switch 87, and the second contact 85 c is connected to the stroke switch 86. The cab lock switch 85 is configured such that the movable iron piece 85d is turned on to the first contact 85b only when the cab 1 is unlocked by the cab block device 94. The cab lock operation of the cab lock device 94 is automatically executed, but the cab lock release is executed by a manual command when tilting up.
[0027]
The stroke switch 86 is constituted by a limit switch and is installed in the tilt cylinder device 3 as shown in FIG. 3 so as to detect a state in which the piston rod 4 of the tilt cylinder device 3 is most shortened. It is configured. As shown in FIG. 7, the stroke switch 86 is connected in series between the second contact 85c of the cab lock switch 85 and the switching valve switch 87, and is turned off only when the piston rod 4 is shortened most. It is configured to be turned on at other times.
[0028]
The switching valve switch 87 is installed in the pump switching valve unit shown in FIG. 8 so as to detect the switching operation of the switching lever of the switching valve 15. That is, as shown in FIG. 8, a switching valve switch 87 for detecting the switching lever 15 a is installed at the tilt-up side position of the switching valve 15. As shown in FIG. 7, the switching valve switch 87 includes a fixed contact 87 a, a first contact 87 b, a second contact 87 c, and a movable iron piece 87 d, and the fixed contact 87 a includes the stroke switch 86 and the cab switch 85. The first contact 87 b is connected to the cab stopper switch 88 in series, and the second contact 87 c is connected to the cab stopper switch 88 in parallel. The switching valve switch 87 is configured such that the movable iron piece 87d is turned on to the first contact 87b only when the switching valve 15 is switched to the tilt-up side.
[0029]
The cab stopper switch 88 is constituted by a limit switch, and is arranged on the cab lowering prevention device 20 as shown in FIGS. 3 and 4. As shown in FIG. Is detected to be prevented from being lowered by the cab lowering prevention device 20. As shown in FIG. 7, the cab stopper switch 88 is connected in series to the first contact 87 b of the switching valve switch 87 and is turned off when the cab 1 is prevented from being lowered by the cab lowering prevention device 20. The cab lowering prevention device 20 is configured to be turned on when released by the release cylinder device 30.
[0030]
The neutral switch 89 is connected to the first contact 87b of the switching valve switch 87 via the cab stopper switch 88 and directly connected to the second contact 87c of the switching valve switch 87, and only when the transmission is in the neutral position. It is configured to turn on and turn off at other times. The thermal switch 90 is connected in series between the neutral switch 89 and the pump switch 91, and is configured to be turned off only when overheating of the motor 8 is detected, and to be turned on at other times. The pump switch 91 is connected in series between the thermal switch 90 and the relay coil 84b, and is configured to be turned on by being pushed by hand when the motor 8 is driven at a constant off state. The buzzer 92 is connected between the neutral switch 89 and the thermal switch 90.
[0031]
As shown in FIG. 3, a valve unit 40 is installed at the end of the cylinder 5 of the tilt cylinder device 3 on the frame side, and the valve unit 40 is shown in FIG. 9 according to this embodiment. A pilot check valve 16 is formed.
[0032]
As shown in FIG. 9, a valve passage 41 of the pilot check valve 16 is opened in the lateral direction (hereinafter, referred to as a left-right direction) on the body 40 a of the valve unit 40. The primary port 42 and the secondary port 43 are connected so as to be orthogonal to the valve path 41 at positions separated from each other. The primary port 42 is connected to the load port a of the switching valve 15 of the raising side oil passage 11, and the secondary port 43 is connected to the raising side hydraulic chamber 5 a of the cylinder 5. A valve port 44 is formed between the primary port 42 and the secondary port 43 in the valve passage 41, and a valve seat 45 is formed around the valve port 44. A valve body 46 made of a ball is disposed on the valve seat 45 so that the valve port 44 is opened and closed. The valve body 46 is constantly urged by a valve spring 47 in the direction of seating on the valve seat 45. Yes. The valve spring 47 applies a reaction force to a plug 48 screwed into one end portion (hereinafter referred to as a right end portion) of the valve passage 41 to urge the valve body 46 to the left.
[0033]
A cylinder chamber 50 having two chambers, a large-diameter chamber 50a and a small-diameter chamber 50b, is formed on the extension line of the valve passage 41 in the body 40a. One end of the release oil passage 37 and one end of the pilot passage 49 are connected to the large-diameter chamber 50 a of the cylinder chamber 50. The other end of the release oil passage 37 is connected to the cylinder chamber 32 of the release cylinder device 30, and the other end of the pilot passage 49 is connected to the load port b of the switching valve 15. A pilot piston 51 having a large diameter portion and a small diameter portion is provided inside the cylinder chamber 50. The large-diameter chamber 50a of the cylinder chamber 50 accommodates a large-diameter portion (hereinafter referred to as a large-diameter portion) 51a of the pilot piston 51, and the small-diameter chamber 50b of the cylinder chamber 50 includes a small-diameter portion (hereinafter referred to as the pilot-piston 51). The small-diameter portion) 51b is slidably fitted in the left-right direction in a state of being sealed by the seal ring 58. The seal ring 58 is held by a cap 59 that is press-fitted into the left end opening of the small-diameter chamber 50b and joined.
[0034]
Of the small-diameter chamber 50b of the cylinder chamber 50. right A guide hole 53 is formed at the end, and a pilot piston rod (hereinafter referred to as a rod) 52 that is integrally projected at the right end of the small-diameter portion 51 b is inserted into the guide hole 53 and inserted into the valve body 46. Opposed. A piston spring 56 is interposed between the right end wall of the large-diameter chamber 50a and the spring seat portion 51c formed at the left end of the pilot piston 51 in an accumulated state. That is, the piston spring 56 always applies a reaction force to the right end wall of the large-diameter chamber 50a to urge the pilot piston 51 in a direction away from the valve body 46. The left end of the pilot piston 51 is defined by a plug 57 screwed into the left end of the large diameter chamber 50a. In FIG. 9, 17 is a stop, and 95 is a filter.
[0035]
The small-diameter portion 51b is slidably fitted in the small-diameter chamber 50b of the cylinder chamber 50 while being sealed by the seal ring 58, so that the cross-sectional area of the small-diameter portion 51b constitutes an effective pressure receiving area of the pilot piston 51. Will be. That is, if the cross-sectional area of the small diameter portion 51b of the pilot piston 51 is A, the elastic force of the piston spring 56 is F, and the sum of the elastic force of the valve spring 47 and the resistance force of the seal ring 58 is α, the pilot piston 51 The pressure in the large-diameter chamber 50a necessary for moving the cylinder chamber 50a, that is, the pilot pressure P is set by P = (F + α) / A. And the cross-sectional area of the small diameter part 51b of the pilot piston 51 which concerns on this embodiment is set to 1/4 with respect to the area of the effective pressure receiving part of the pilot piston in this kind of conventional pilot operation type check valve. . Therefore, the pilot pressure of the pilot check valve 16 according to the present embodiment is set to about four times the pilot pressure of the conventional pilot operated check valve of this type.
[0036]
Next, the operation will be described.
[0037]
When the driver tries to tilt up the cab 1, first, the switching valve 15 is switched to the tilt-up side. At this time, the cab lock of the cab lock device 94 is manually released, so that the movable iron piece 85d of the cab lock switch 85 is turned on to the first contact 85b. When the pump switch 91 is turned on and the motor 8 rotates and the pump 13 is driven, the pressure oil of the pump 13 is pumped to the load port a of the raising side oil passage 11 by the switching valve 15 in FIG. The The pressure oil pumped to the load port a of the raising side oil passage 11 flows into the raising side hydraulic chamber 5a of the cylinder 5 of the tilt cylinder device 3 through the pilot check valve 16, and the piston rod 4 is operated to extend, The cab 1 is lifted from the frame 2 and tilted up.
[0038]
At this time, in order to extend the piston rod 4, it is necessary to discharge the pressure oil in the lower hydraulic chamber 5 b of the cylinder 5. In this embodiment, in FIG. 2, the pressure oil in the lower hydraulic chamber 5 b of the cylinder 5 is the communication oil passage 38, the cylinder chamber 32 of the release cylinder device 30, the release oil passage 37, and the lower oil of the switching valve 15. It is discharged to the tank 14 via the load port b and the tank port T of the path 12. Therefore, the piston rod 4 of the tilt cylinder device 3 can be extended to tilt the cab 1 up.
[0039]
At this time, since the pressure oil in the lower hydraulic chamber 5b of the cylinder 5 is gradually discharged by the throttle 39, the center of gravity of the cab tilts forward beyond the fulcrum and a tensile load is applied to the cylinder 5. The extension operation of the piston rod 4 of the tilt cylinder device 3 becomes gentle, and the cab 1 can be tilted up safely.
[0040]
As shown in FIG. 4A, when the tilt-up operation is performed, the claw portion 27 of the lowering prevention member 26 of the cab lowering prevention device 20 is pressed against the teeth 22 of the stay 21 by the elastic force of the tension spring 29. Go sliding while being. That is, since the teeth 22 are formed in a semi-trapezoidal shape with a lower slope, the claw portion 27 slides without engaging with the teeth 22. That is, the tilt cylinder device 3 can tilt up the cab 1 without being obstructed by the cab lowering prevention device 20.
[0041]
As described above, the cab 1 is tilted up by the extension operation of the piston rod 4 of the tilt cylinder device 3, and as shown in FIG. 4B, the lower end surface of the stay 21 is lowered. When the height of the claw portion 27 is reached, the lowering prevention member 26 is pulled by the tension spring 29, whereby the claw portion 27 is engaged with the lower end surface of the stay 21. Since the stay 21 is mechanically locked by the engagement of the claw portion 27 of the lowering prevention member 26 with the lower end surface of the stay 21, the piston rod 4 to which the upper end of the stay 21 is fixed is shortened, that is, the cab 1 is reliably prevented from descending.
[0042]
As shown in FIG. 4B, when the claw portion 27 of the lowering prevention member 26 is engaged with the lower end surface of the stay 21, the lever 88 a protruding from the lowering prevention member 26 is moved to the cab stopper switch 88. Press to turn it off. For this reason, in the electric circuit shown in FIG. 7, the relay coil 84b is demagnetized, the relay switch 84a is turned off, and the drive of the pump 13 by the motor 8 is automatically stopped.
[0043]
In the present embodiment, the tilt cylinder device 3 reaches a full stroke immediately after the lower end surface of the stay 21 reaches the claw portion of the lowering prevention member 26, and as shown in FIG. Since the release oil passage 37 of the cylinder device 30 is connected to the load port b of the lower oil passage 12 of the switching valve 15, the pressure in the cylinder chamber 3 of the release cylinder device 30 is preset in the release cylinder device 30. There is almost no rise above the released release pressure. Further, even if the pressure in the cylinder chamber 32 becomes equal to or higher than the release pressure of the release cylinder device 30 due to pipe resistance or the like, when the tilt cylinder device 3 is full stroke, the extension operation of the piston rod 4 is stopped, that is, the pressure is lowered. Since oil does not flow out from the side hydraulic chamber 5b, the pressure in the cylinder chamber 32 immediately decreases. Therefore, the tension spring 29 can rotate the lowering prevention member 26 without being hindered by the plunger 34 of the release cylinder device 30 to engage the claw portion 27 with the stay 21, and the cab stopper switch 88. It can be turned off by lever 88a.
[0044]
Thereafter, when the driver tries to tilt down the cab 1, the switching valve 15 is first switched to the down side, and then the pump switch 91 is turned on. Then, the pump 13 is driven by the motor 8, and the pressure oil of the pump 13 is pumped to the load port b of the lower side oil passage 12 by the switching valve 15. The pressure oil pressure-fed to the load port b of the lower side oil passage 12 enters the lower side hydraulic chamber 5b of the cylinder 5 of the tilt cylinder device 3 into the release oil passage 37, the cylinder chamber 32 of the release cylinder device 30, and the communication oil. The cab 1 is tilted down by flowing in via the path 38 and shortening the piston rod 4.
[0045]
At this time, in order for the piston rod 4 to perform a shortening operation, it is necessary to discharge the pressure oil in the raising side hydraulic chamber 5 a of the cylinder 5. In this embodiment, when the pressure in the lower side oil passage 12 becomes equal to or higher than the pilot pressure value set in the pilot check valve 16, the release oil passage 37 and the pilot passage 49 are opened as shown in FIG. Since the pilot piston 51 moves rightward in the connected cylinder chamber 50, the valve body 46 of the pilot check valve 16 moves away from the valve seat 45 and opens the valve port 44. In FIG. 2, when the pilot check valve 16 is opened, the pressure oil in the raised hydraulic chamber 5 a of the cylinder 5 is discharged to the tank 14 via the pilot check valve 16 and the switching valve 15. Therefore, the piston rod 4 of the tilt cylinder device 3 can be shortened to tilt down the cab 1.
[0046]
Incidentally, the pressure oil flowing in the reverse direction from the secondary port 43 to the primary port 42 through the pilot check valve 16 is throttled through the secondary port 43, the valve port 44, the throttle 17 and the primary port 42, so The pressure oil in the raised hydraulic chamber 5a is gradually discharged. Therefore, the extension operation of the piston rod 4 of the tilt cylinder device 3 becomes gentle, and the cab 1 can be tilted down safely.
[0047]
During the tilt-down operation described above, as shown in FIG. 4B, the claw portion 27 of the lowering prevention member 26 of the cab lowering prevention device 20 remains engaged with the lower end surface of the stay 21. The piston rod 4 of the tilt cylinder device 3 cannot be shortened. Therefore, in the present embodiment, before the piston rod 4 of the tilt cylinder device 3 starts to shorten, the release cylinder device 30 is operated to release the engagement of the lowering prevention member 26 with the stay 21. Has been.
[0048]
That is, as shown in FIG. 2, when the switching valve 15 is switched to the tilt-down side and the pump switch 91 is turned on, the pressure oil of the pump 13 flows through the pump port P and the load port b of the switching valve 15. Via the lower oil passage 12, the release oil passage 37, the cylinder chamber 32 of the release cylinder device 30, the communication oil passage 38, and the throttle 39, the oil is supplied to the lower hydraulic chamber 5 b of the cylinder 5. The pressure oil supplied to the lower hydraulic chamber 5b acts to push down the piston 4a of the piston rod 4. For this reason, the pressure oil in the raising side hydraulic chamber 5 a tends to flow into the raising side oil passage 11. However, since the lift side oil passage 11 is closed by the pilot check valve 16, the pressure oil in the lift side hydraulic chamber 5a cannot flow. On the other hand, since the pressure oil from the pump 13 is supplied to the lower side oil passage 12, the pressure in the cylinder chamber 32 rises, and the plunger 34 is pushed out to push the push portion 35 as shown in FIG. As a result, the engagement of the stay 21 and the claw portion 27 is released.
[0049]
By the way, in order for the release cylinder device 30 to reliably release the piston rod 4 of the tilt cylinder device 3 before the shortening operation starts, the pilot pressure value of the pilot check valve 16 is set between the stay 21 and the claw portion 27. It is necessary to set higher than the hydraulic pressure when the engagement is released. In general, when setting the pilot pressure of the pilot operated check valve high, it is usual to set the spring load of the valve spring pushing the valve body high or set the spring load of the pilot piston spring high. It is. However, since the body of the valve unit of the pilot operated check valve mounted on the carbylate device needs to be formed in a small size, there is a limit to setting the spring load of the valve spring or the pilot piston spring high.
[0050]
Therefore, in the present embodiment, the cross-sectional area A of the small diameter portion 51b constituting the effective pressure receiving area of the pilot piston 51 is set to a quarter of the effective pressure receiving area of the pilot piston in the conventional pilot operated check valve. Thus, when the same hydraulic pressure is applied to the large-diameter chamber 50a of the cylinder chamber 50, the force with which the pilot piston 51 pushes the valve body 46 is reduced to about one-fourth of the conventional one. This means that the valve body 46 cannot be opened unless the pilot pressure of the pilot check valve 16 is set to four times the pilot pressure in the conventional pilot operated check valve. That is, after the pressure of the lowering oil passage 12 becomes sufficiently high and the release cylinder device 30 is operated, the pilot check valve 16 is opened and the raising oil passage 11 is released. That is, since the pilot pressure value of the pilot check valve 16 is set high, the release cylinder device 30 is surely released before the shortening operation of the piston rod 4 of the tilt cylinder device 3 starts. Can do.
[0051]
Even after the engagement is automatically released as described above, as long as the hydraulic pressure of the lower side oil passage 12 maintains the set value or more, the release cylinder device 30 is connected to the stay 21 of the lowering prevention member 26. The disengaged state is maintained. In other words, the tilt cylinder device 3 can tilt the cab 1 down without being obstructed by the cab lowering prevention device 20.
[0052]
In FIG. 8, when the switching lever 15a of the switching valve 15 is manually operated to the tilt-down position, the switching valve switch 87 is automatically switched away from the switching lever 15a. The iron piece 87d is turned on at the second contact 87c. As a result, since the current is supplied to the buzzer 92 via the cab switch 85 → the switching valve switch 87 → the neutral switch 89, the buzzer 92 sounds. Since the buzzer 92 sounds to warn that the cab 1 starts to tilt down, safety is ensured.
[0053]
On the other hand, as described above, when the switching valve 15 is switched to the tilt-down side and the pump switch 91 is turned on, the lowering prevention member 26 is moved to the tension spring 29 around the pin 28 by the plunger 34 of the release cylinder device 30. The lever 88 a protruding from the descending prevention member 26 is automatically separated from the cab stopper switch 88 because the lever 88 a is rotated against the cab stop switch 26. As a result, the closed cab stopper switch 88 automatically returns to the original ON state when not pressed.
[0054]
As described above, when the cab 1 is tilted down and the cab 1 is lowered to a predetermined position, the latch is engaged with the lock pin of the cab lock device 94, so that the movable iron piece 85d of the cab lock switch 85 is connected to the first contact 85b. Automatically switches to the side. Next, when the piston rod 4 of the tilt cylinder device 3 reaches the minimum shortened stroke position, the stroke switch 86 is automatically turned off in FIG. If the neutral switch 89 is turned off, the vehicle returns to the normal driving state shown in FIG.
[0055]
According to the embodiment, the following effects can be obtained.
[0056]
Connect the cylinder chamber of the release cylinder device to the cylinder chamber of the pilot check valve interposed in the oil passage on the raising side, and change the effective pressure receiving cross-sectional area of the pilot piston to the effective pressure receiving cross-sectional area of the conventional pilot operated check valve By setting the value to one-fourth, the pilot pressure value of the pilot check valve can be set high without increasing the spring load of the valve spring and piston spring. The release cylinder device can be reliably released before the shortening operation of the rod starts.
[0057]
FIG. 10 shows a pilot check valve used in a carbitol device according to another embodiment of the present invention.
[0058]
The pilot check valve 16A according to this embodiment is different from the pilot check valve 16 according to the above embodiment in that a sleeve 54 is interposed between the small diameter chamber 50b of the cylinder chamber 50 and the small diameter portion 51b of the pilot piston 51. It is a point that has been. That is, as shown in FIG. 10A, a cylindrical sleeve 54 is fitted into the small diameter portion 50b of the cylinder chamber 50 so as to be slidable in the left-right direction while being sealed by the seal ring 55. The small diameter portion 51b of the pilot piston 51 is inserted into the cylindrical hollow portion of the sleeve 54 from the left side and is slidably fitted in the left-right direction. A seal ring 58 is interposed between the inner peripheral surface of the hollow portion of the sleeve 54 and the outer peripheral surface of the small diameter portion 51b of the pilot piston 51 so that the seal ring 58 maintains the sealed state. It is held by a cap 59 that is press-fitted into the opening and joined.
[0059]
The sleeve 54 is slidably fitted in the small diameter chamber 50 b of the cylinder chamber 50 while being sealed by the seal ring 55, and the small diameter portion 51 b of the pilot piston 51 is sealed by the seal ring 58 in the cylindrical hollow portion of the sleeve 54. By being slidably inserted in this state, the cross-sectional area of the small-diameter portion 51b of the pilot piston 51 constitutes an effective pressure receiving area of the pilot piston 51. Also in this embodiment, as in the previous embodiment, the cross-sectional area of the small diameter portion 51b of the pilot piston 51 is a quarter of the area of the effective pressure receiving portion of the pilot piston in this type of conventional pilot operated check valve. Is set to one. Therefore, the pilot pressure of the pilot check valve 16 according to the present embodiment is set to about four times the pilot pressure in this type of conventional pilot operated check valve. That is, the same effect as that of the cabylt apparatus according to the embodiment can be obtained in the cabylt apparatus according to the present embodiment.
[0060]
Incidentally, as shown in FIG. 9, when the small diameter portion 51 b of the pilot piston 51 is directly fitted into the small diameter chamber 50 b of the cylinder chamber 50 in the pilot check valve 16, the small diameter portion 51 b and the small diameter portion 51 b are arranged. There is a possibility that the seal ring 58 and the cap 59 that maintain the seal with the chamber 50b are pushed out by the acting force of the pressure of the primary port 42 adjacent to the small diameter chamber 50b. That is, when the pressure of the primary port 42 connected to the load port a of the upside oil passage 11 is increased during the tilt-up operation, the pressure of the small diameter chamber 50b is increased. Therefore, the seal ring 58 and the cap that maintain the seal of the small diameter chamber 50b In 59, the acting force pushing in the left direction increases. However, the cap 59 for holding the seal ring 58 is difficult to be screwed into the small-diameter chamber 51 for reasons such as preventing damage to the seal ring 58. right The cap 59 is weak against the pushing force from the direction. right There is a possibility of being pushed out by the pushing force from the direction.
[0061]
However, in the pilot check valve 16A shown in FIG. 10 according to the present embodiment, since the small diameter portion 51b is fitted into the small diameter chamber 50b via the sleeve 54, the small diameter portion 51b and the small diameter chamber 50b The seal ring 58 and the cap 59 that maintain the seal are not pushed out by the acting force of the pressure of the primary port 42 during the tilt-up operation. That is, when the pressure of the primary port 42 rises above the pressure defined by the piston spring 56, the sleeve 54 receives the acting force in the left direction and resists the piston spring 56. Small diameter chamber 50b Move left Let me , A cap 59 press-fitted into the left end of the sleeve 54 The pilot piston 51 stops when it comes into contact with the right end surface. That is, the pushing force applied to the seal ring 58 and the cap 59 by the pressure of the primary port 42 is absorbed by the leftward movement of the sleeve 54. Since the coupling force can be set as weak as the pushing force is absorbed, the cap 59 holding the seal ring 58 may be coupled to the sleeve 54 by simple coupling means such as press fitting.
[0062]
Even if the sleeve 54 is moved to the left by the pressing force due to the pressure of the primary port 42 during the tilt-up operation, the pilot piston 51 does not move. The valve is opened against the pressure, and the pressure oil flows out to the secondary port 43.
[0063]
According to the present embodiment, the following effects can be obtained in addition to the embodiment.
[0064]
1) By fitting the small diameter portion of the pilot piston in the pilot check valve into the small diameter chamber of the cylinder chamber via the sleeve, the seal ring that maintains the seal between the small diameter portion and the small diameter chamber and the cap that holds this are the primary ports. Since the pressing force applied by the pressure can be absorbed by the movement of the sleeve, it is possible to prevent the seal ring and the cap from being pushed out by the acting force of the primary port pressure during the tilt-up operation.
[0065]
2) By absorbing the acting force of the pressure of the primary port during the tilt-up operation by moving the sleeve, the cap holding the seal ring can be coupled to the sleeve by coupling means such as press fitting, which increases the manufacturing cost. The value of the pilot pressure of the pilot check valve can be set high while being suppressed.
[0066]
Needless to say, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.
[0067]
The pilot check valve to which the release cylinder device is connected is not limited to being provided in the valve unit of the tilt cylinder device, but may be provided in the cylinder block of the release cylinder device.
[0068]
In the above embodiment, the case where the cylinder chamber of the pilot check valve is connected to the lower side oil passage of the tilt cylinder device via the cylinder chamber of the release cylinder device has been described. May be directly connected to the lower oil passage of the carbitol device.
[0069]
Further, in the above-described embodiment, the case where the pilot check valve is used in the hydraulic drive circuit of the cabylt device has been described. However, the pilot check valve according to the present invention is hydraulically driven such as an on-vehicle hydraulic crane or a tailgate opening / closing device. Can be used for all circuits.
[0070]
【The invention's effect】
As described above, according to the present invention, before the shortening operation of the piston rod of the tilt cylinder device starts by setting the pilot pressure high without changing the spring load of the conventional pilot operated check valve. Since the release cylinder device can be reliably released, the performance, safety and reliability of the carbylate device can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a cab-over type automobile equipped with a cabylt device.
FIG. 2 is a hydraulic circuit diagram of a carbitol device using a pilot check valve according to an embodiment of the present invention.
FIG. 3 shows a tilt cylinder device, where (a) is a side view and (b) is a bottom view.
FIGS. 4A and 4B are side views showing the operation of the tilt cylinder device, where FIG. 4A shows before the lowering prevention and FIG. 4B shows the lowering prevention time.
FIG. 5 is an enlarged side cross-sectional view showing a lowering prevention state of the release cylinder device.
FIG. 6 is an enlarged side cross-sectional view showing a state in which the lowering prevention is released.
FIG. 7 is a circuit diagram showing a motor drive circuit.
FIG. 8 shows a pump switching valve unit in which a switching valve switch is installed, where (a) is a front view and (b) is a side view.
9A and 9B show a pilot check valve used in the tilt cylinder device, wherein FIG. 9A is an enlarged sectional view taken along line IX-IX in FIG. 3A, and FIG. 9B is FIG. It is sectional drawing which follows the bb line.
FIG. 10 shows a pilot check valve according to another embodiment used in the tilt cylinder device, (a) is an enlarged sectional view corresponding to FIG. 9 (a), and (b) is FIG. It is sectional drawing which follows the bb line of a).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cab, 2 ... Frame, 3 ... Cylinder apparatus for tilting, 4 ... Piston rod, 4a ... Piston, 5 ... Cylinder, 5a ... Frame side hydraulic chamber (raising side hydraulic chamber), 5b ... Cab side hydraulic chamber (lower side) Hydraulic chamber), 7 ... Manual pump, 8 ... Motor, 9 ... Relief valve, 10 ... Hydraulic drive circuit, 11 ... Up side supply / discharge oil passage (up side oil passage), 12 ... Down side supply / discharge oil passage (down side) (Oil path), 13 ... pump, 14 ... tank, 15 ... manual switching valve (switching valve), 15a ... switching lever, 16 ... pilot check valve, 17 ... throttle, 18 ... filter, 19 ... check valve, 20 ... Cab lowering prevention device, 21 ... stay, 22 ... teeth, 23 ... protective cover, 24 ... yoke, 24a ... locking part, 25 ... notch part, 26 ... descending prevention member, 26a ... locking part, 27 ... claw part, 28 ... Pin, 29 ... Tension spring, 30 ... Release Cylinder device, 32 ... cylinder chamber, 33 ... cylinder head, 34 ... plunger, 35 ... push part, 36 ... return spring, 37 ... release oil passage, 38 ... communication oil passage, 39 ... throttle, 40 ... Valve unit, 40a ... Body, 41 ... Valve path, 42 ... Primary port, 43 ... Secondary port, 44 ... Valve port, 45 ... Valve seat, 46 ... Valve body, 47 ... Valve spring, 48 ... Plug, 49 ... Pilot passage, 50 ... cylinder chamber, 50a ... large diameter chamber, 50b ... small diameter chamber, 51 ... pilot piston, 51a ... large diameter portion, 51b ... small diameter portion, 51c ... spring seat portion, 52 ... rod (pilot piston rod), 53 ... guide hole, 54 ... sleeve, 55 ... seal ring, 56 ... piston spring, 57 ... plug, 58 ... seal ring, 59 ... cage Tsu 80 ... motor drive circuit 81 ... power source 82 ... fuse 83 ... control circuit 84 ... relay 84a ... relay switch 84b ... relay coil 85 ... cabot switch 85a 87a ... fixed contact 85b 87b ... first contact, 85c, 87c ... second contact, 85d, 87d ... movable iron piece, 86 ... stroke switch, 87 ... switch valve switch, 88 ... cab stopper switch, 88a ... lever, 89 ... transmission neutral detection switch (neutral Switch), 90 ... thermal switch, 91 ... pump switch, 92 ... buzzer, 93 ... fuse, 94 ... cab lock device, 95 ... filter.

Claims (3)

A cab lowering prevention device is assembled to a tilt cylinder device interposed between the cab and the frame to tilt the cab, and one end of the cab lowering prevention device is pivotally attached to the piston rod of the tilt cylinder device. In a cabylt device comprising a stay and a lowering prevention member that is fixed to a cylinder of the tilt cylinder device and engages with the stay,
A release cylinder device for releasing the engagement of the lowering prevention member with the stay is installed in a cylinder of the tilt cylinder device, and a cylinder chamber of the release cylinder device is provided on the lower side supply / discharge of the tilt cylinder device. Connected to an oil passage and a pilot passage of a pilot operated check valve interposed in the raising side supply / discharge oil passage of the tilt cylinder device,
The pilot operated check valve has a valve port formed between a primary port and a secondary port, a valve seat formed around the valve port, and a seat on and off the valve seat to open and close the valve port. And a cylinder chamber formed adjacent to the valve opening and connected to the pilot passage, and a pilot piston mounted in the cylinder chamber and having a piston rod facing the valve body. By setting the effective pressure receiving area of the pilot piston small, the pilot pressure of this pilot operated check valve is set high ,
The cylinder chamber is formed with at least two chambers, a large-diameter chamber to which the pilot passage is connected and a small-diameter chamber adjacent to the large-diameter chamber, and the pilot piston is disposed in the large-diameter chamber. The large-diameter portion and the small-diameter portion connected to the large-diameter portion and disposed in the small-diameter chamber are configured by at least two portions, and the area of the small-diameter portion is set to the effective pressure receiving area of the pilot piston. Kyabuchiruto and wherein the are. The cabylt apparatus according to claim 1, wherein a sleeve into which a small diameter portion of the pilot piston is slidably fitted is fitted in the small diameter chamber of the cylinder chamber . The cabylt device according to claim 1 or 2, wherein the pilot operated check valve is disposed at one end of a cylinder of the tilt cylinder device.

Images