JP5859861B2 - forklift - Google Patents

Description

  The present invention relates to a forklift.

  In general, reach-type forklifts, counterweight-type forklifts, and the like are known as vehicles used for carrying goods. A forklift is equipped with a fork (claw) that handles luggage in front of the vehicle and a mast (support) that supports the fork so that it can move in the vertical direction. I have. The rear wheels are steered wheels and are also drive wheels that are rotationally driven by a drive source such as a motor that drives the forklift. In many cases, one rear wheel is arranged close to one side surface (for example, the left side surface) of the rear of the forklift vehicle. In this case, auxiliary wheels are arranged on the other side surface (for example, the right side surface) on the rear side of the vehicle.

  Further, the forklift is provided with a steering angle sensor for measuring the steering angle of the rear wheel, a sensor for measuring the operation state, the motion state, and the like of the forklift. The outputs of these sensors are used for forklift drive control (see, for example, Patent Document 1).

  The steering angle sensor is disposed in the vicinity of the gear wheel that transmits the steering operation performed by the driver to the steering wheel to the rear wheels. The steering angle sensor is provided with a pinion gear meshed with the gear wheel, and the steering angle sensor measures the steering angle of the rear wheel transmitted through the pinion gear.

  Here, the steering operation performed on the steering wheel is transmitted from the steering wheel to the rear wheel via a steering shaft, a gear portion provided at an end portion of the steering shaft, and a gear wheel meshed with the gear portion, for example. Has been. The above-described gear portion and gear wheel are rotatably held by the gear box. Further, the gear box also supports the rear wheels so that they can be steered.

  In order to prevent the above-described steering angle sensor from being broken, a range to be disposed with respect to the gear wheel is determined in order to ensure measurement accuracy. In other words, the range of the arrangement position between the pinion gear of the steering angle sensor and the gear wheel, in particular, the range of the inter-axis distance is determined. For example, if the distance between the axes is too close, the radial (radial) force acting on the steering angle sensor shaft becomes too large, and the steering angle sensor may break down. Further, if the distance between the shafts is too large, the gap (backlash) between the pinion gear and the gear wheel becomes too large, and it may be difficult to ensure the measurement accuracy of the steering angle.

  In order to solve this problem, conventionally, a method has been employed that facilitates adjustment of the arrangement position of the pinion gear with respect to the gear wheel using a bracket. That is, the bracket to which the steering angle sensor is attached is configured to be attached to the gear box that supports the gear wheel, and a method of adjusting the position where the bracket is attached to the gear box has been adopted.

JP 2000-062428 A

However, the above adjustment method has the following problems.
First, there is a problem that it is difficult to ensure measurement accuracy of the steering angle sensor. Generally, when a bracket is attached to a gear box and fixed, a screw member such as a bolt is often used. When fixing with the screw member, it is desirable to tighten the screw member with a predetermined torque in order to ensure the fixing, that is, to manage the tightening torque of the screw member. However, if the screw member is tightened after adjusting the relative position between the pinion gear and the gear wheel, the bracket may rotate with the tightening. As a result, the relative position between the pinion gear and the gear wheel moves from the adjusted position, making it difficult to manage the backlash between the pinion gear and the gear wheel, which in turn makes it difficult to ensure the measurement accuracy of the steering angle sensor. It was.

  This problem has a characteristic that, when performing maintenance of a forklift, particularly maintenance of the vicinity of the rear wheel, the steering angle sensor is often attached and detached, so that it is easily manifested.

  Further, since the direction in which the arrangement position of the steering angle sensor can be adjusted is limited, there is a problem that the arrangement accuracy in other directions is likely to deteriorate. When adjusting the arrangement position by the bracket, a long hole extending in the direction of adjusting the arrangement position is often formed in the bracket. In this case, the arrangement position in the direction in which the long holes extend can be adjusted, but adjustment in a different direction (for example, a direction different from the above-described inter-axis distance direction) is difficult. Then, in the different directions described above, the accumulated value of the tolerance between the pinion gear and the gear wheel is increased by the presence of the bracket, and the arrangement accuracy is likely to deteriorate. The deterioration in the placement accuracy in the different directions has a problem that the measurement accuracy is deteriorated although the influence on the measurement accuracy of the steering angle sensor is small compared with the placement accuracy in the inter-axis distance direction.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a forklift capable of suppressing deterioration in measurement accuracy of a steering angle sensor and suppressing occurrence of a failure.

In order to achieve the above object, the present invention provides the following means.
The forklift of the present invention is capable of rotating the first gear to which the steering operation by the driver is transmitted from the steering unit, the second gear rotated by the first gear, and the first gear and the second gear. Steering angle sensor unit that measures the steering angle of the steered wheels by rotation of a sensor-side gear that is directly attached in contact with a machining surface provided in the gear case and meshed with the second gear. And is provided.

  According to the forklift of the present invention, since the steering angle sensor unit is directly attached to the machining surface of the gear case that holds the first gear and the second gear, the inter-shaft distance between the sensor-side gear and the second gear is It can be within a desired range.

  In other words, by directly attaching the steering angle sensor portion having the sensor side gear to the processed surface of the gear case, the sensor side gear is also the same as the first gear and the second gear held by the gear case with high relative position accuracy. It can arrange | position with the precision of a high relative position with respect to a 2nd gear.

  Since the steering angle sensor unit is attached in a state where the steering angle sensor unit is in contact with the machining surface of the gear case, a deviation occurs in the relative position to the second gear that has been aligned when the steering angle sensor unit is installed. Can be suppressed. Further, even when the steering angle sensor unit is removed and attached during maintenance work, the sensor side gear and the second gear are simply installed by attaching the steering angle sensor unit to the processing surface in contact with the steering angle sensor unit. The distance between the axes can be within a desired range.

  By making the processing surface a surface that intersects the above-mentioned direction of the inter-axis distance, preferably a surface that intersects less than ± 45 °, and more preferably an orthogonal surface, the inter-axis distance is within a desired range. It becomes easy to pay. The processed surface is a flat surface that has been subjected to machining such as cutting.

  Further, instead of defining the direction of the machining surface using the direction of the inter-axis distance as described above, the direction of the machining surface may be defined using the front-rear direction or the left-right direction of the forklift, and the steered wheels are steered. The direction of the processing surface may be defined using the direction of the rotation axis that rotates.

  Further, compared to the case where the steering angle sensor unit is attached to the gear case via a bracket, parts such as a bracket and a fastening member for fixing the bracket can be eliminated, so that forklifts, more specifically, steering of forklifts The manufacturing cost of the apparatus can be reduced.

In the said invention, it is preferable that the angle | corner which the direction of the center distance of the said 2nd gear and the said sensor side gear and the normal line direction of the said processing surface make is less than 45 degree | times.

In the above invention, it is preferable that the steering angle sensor unit has a sensor body attached to the processing surface, and the sensor side gear attached to the sensor body.
By attaching the sensor main body directly to the machining surface in this way, it is easier to attach and remove the steering angle sensor unit than when the sensor-side gear is attached to the machining surface. For example, the steering angle sensor unit can be easily removed and attached during maintenance work.

  Examples of the attachment method include a method in which a plurality of through holes extending in parallel are formed in the sensor body, and the sensor body is attached and fixed to the processing surface by a fastening member such as a bolt inserted into the through hole. In the case of using this method, the distance between the axes is set by setting the direction in which the through hole extends to the direction intersecting the processing surface, preferably the direction in which the crossing angle is less than ± 45 °, and more preferably the direction orthogonal. It becomes easy to fit within the desired range.

In the said invention, it is preferable that the normal line direction of the said processed surface is parallel to the front-back direction of a vehicle body.

In the said invention, it is preferable that the outer surface of the said gear case is provided with the protrusion part integrally protruded toward the outward direction, and the said process surface is provided in this protrusion part.
Thus, by forming the machining surface on the protruding portion provided in the gear case, it is possible to facilitate the attaching and detaching operations of the steering angle sensor portion. Furthermore, compared with the case where a protrusion part is not provided, the area | region which can arrange | position a steering angle sensor part can be expanded.

  According to the forklift of the present invention, the steering angle sensor unit is directly attached to the machining surface of the gear case that holds the first gear and the second gear, so that the center distance between the sensor side gear and the second gear can be set to a desired value. Since it can be within the range, it is possible to suppress the deterioration of the measurement accuracy of the steering angle sensor and to suppress the occurrence of failure.

It is a mimetic diagram explaining the whole forklift concerning the embodiment of the present invention. It is a schematic diagram explaining the structure of a steering device. FIG. 3 is a schematic diagram for explaining an arrangement of gears in the steering device of FIG. 2. FIG. 3 is a top view for explaining the arrangement of the gear case and the steering angle sensor of FIG. 2. It is a schematic diagram explaining the structure of the steering angle sensor part of FIG. FIG. 5 is a top view for explaining another arrangement example of the steering angle sensor of FIG. 4. It is a schematic diagram explaining the other example of arrangement | positioning of the steering angle sensor part in the steering apparatus of FIG. FIG. 5 is a schematic diagram illustrating a configuration in which a sensor side gear of a steering angle sensor is rotatably supported on a gear case.

  A reach-type forklift (hereinafter referred to as “forklift”) according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram illustrating the overall configuration of a forklift 1 according to this embodiment, FIG. 1 (a) is a plan view, and FIG. 1 (b) is a side view.

  In the present embodiment, the present invention is applied to a reach-type forklift, but the object to be applied is not limited to a reach-type forklift, but can also be applied to a counterweight forklift.

  The forklift 1 according to this embodiment is used for transporting luggage, and is particularly used for cargo handling work in a factory, a warehouse, a freight station, a port, or the like. As shown in FIG. 1, the forklift 1 is mainly provided with a vehicle body 10 on which a driver gets in and a cargo handling unit 20 that handles luggage.

  The vehicle body 10 includes a front wheel 11 and a rear wheel 12 that are used for traveling the forklift 1, an outrigger 13 in which the front wheel 11 is disposed, a driver seat 14 in which a driver rides, and a suspension mechanism that connects the rear wheel 12 and caster tires 61. 60 and a steering device 30 for steering the rear wheel 12 are mainly provided.

  The front wheels 11 are a pair of wheels respectively disposed at the front end of the outrigger 13 as shown in FIGS. 1 (a) and 1 (b). In the present embodiment, description will be made by applying to an example in which the front wheel 11 is an idle wheel in which the direction of the rotation shaft is fixed with respect to the vehicle body 10. The rear wheel 12 is a single wheel disposed at the left rear end of the vehicle body 10. The rear wheel 12 is a driving wheel to which a rotational driving force is transmitted from a driving motor 35 to be described later, and is a steering wheel that determines the traveling direction of the forklift 1 in which the direction of the rotating shaft with respect to the vehicle body 10 can be changed.

  The outriggers 13 are a pair of arm-like members provided at the lower front end of the vehicle body 10, and are arranged to extend in parallel from the left and right ends of the lower front end of the vehicle body 10 toward the front. A cargo handling section 20 is disposed between the pair of outriggers 13 and 13, and the cargo handling section 20 is movable between the pair of outriggers 13 and 13 in the front-rear direction.

  The driver's seat 14 is a place provided at the right rear end of the vehicle body 10 where the driver gets into the forklift 1 and operates the forklift 1 in a standing posture. The driver's seat 14 is provided with a steering wheel 31 of the steering device 30, an operation unit 24 such as a lever for operating the cargo handling unit 20, and the like.

  As shown in FIGS. 1 (a) and 1 (b), the cargo handling section 20 includes a fork 21 used to load a load, an elevating body 22 to which the fork 21 is attached, a fork 21 and an elevating body 22. A pair of mast members 23, 23 that are supported so as to be movable in the vertical direction are provided.

  As shown in FIGS. 1A and 1B, the fork 21 is a pair of arm-shaped members provided on the front surface of the lifting body 22, and is directed forward from the left and right ends of the lower end of the front surface of the lifting body 22. Are arranged so as to extend side by side in parallel. The fork 21 is inserted into a pallet insertion hole formed in an approximately rectangular parallelepiped shape on which a load is placed, and lifts or lowers only the pallet or the pallet on which the load is placed.

  The elevating body 22 supports the fork 21 and is movable up and down along the mast material 23 by an elevating cylinder (not shown) disposed between the mast material 23. It is.

  The mast material 23 is a quadrangular prism-shaped member that is arranged to extend in the vertical direction at the front end of the vehicle body 10 and has a U-shaped cross section that is arranged in parallel in the horizontal direction with a gap therebetween. . Further, the pair of mast members 23 and 23 are supported by the fork 21 and the lifting body 22 arranged between them so as to be vertically movable.

  The suspension mechanism 60 is a mechanism for holding the rear wheel 12 and the caster tire 61 in a state in which the rear wheel 12 and the caster tire 61 can be shifted in the vertical direction with respect to the vehicle body 10. The suspension mechanism 60 includes a tire support portion 62 that supports the caster tire 61 upward, a caster link portion 63 that extends from the tire support portion 62 in the left-right direction of the vehicle body 10, and the caster link portion 63 that rotates relative to the vehicle body 10. A pivot fixing portion 64 that can be held, a swing limiting portion 65 that limits the swing range of the caster link portion 63, and an elastic member 66 that is disposed between the caster link portion 63 and the swing limit portion 65. A driven link portion 67 that follows the vertical movement of the rear wheel 12 and a drive link portion 68 that spans between the driven link portion 67 and the rotation fixing portion 64 are provided.

  The rotation fixing portion 64 is an axis that is fixed to the vehicle body 10 and extends in the front-rear direction of the vehicle body 10. The caster link portion 63 has a left end portion rotatably supported by a rotation fixing portion 64, and a right end portion can swing up and down with respect to the vehicle body 10. The drive link portion 68 has a right end portion rotatably supported by a rotation fixing portion 64, and a left end portion swingable in the vertical direction with respect to the vehicle body 10.

  Further, the suspension mechanism 60 is provided with an upper link portion 71 and an upper rotation fixing portion 72 that support the rear wheel 12, the gear case 40, and the like. The upper rotation fixing portion 72 is an axis that is fixed to the vehicle body and extends in the front-rear direction of the vehicle body 10. The upper link portion 71 has a left end portion rotatably supported by the upper rotation fixing portion 72 and a left end portion attached to the gear case 40 so as to be rotatable.

Next, the structure of the steering device 30 and its surroundings, which are the main parts of the present invention, will be described.
As shown in FIG. 2, the steering device 30 is disposed at a position adjacent to the driver's seat 14 at the rear end of the vehicle body 10. 2 and 3, the steering device 30 includes a steering wheel (steering portion) 31, a steering rod 32, a first steering gear (first gear) 33A and a second steering gear 33B, and a ring gear ( (Second gear) 34, drive motor 35 for rotationally driving rear wheel 12, first assist gear 36A, second assist gear 36B and third assist gear 36C, assist motor 37, gear case 40, and steering angle sensor. 50 is mainly provided.

  As shown in FIG. 2, the steering wheel 31 is operated when the driver steers the rear wheel 12, and is disposed so as to be rotatable around a steering rod 32 attached to the center. The steering wheel 31 of the present embodiment is provided with a knob that is a protrusion that is gripped by the driver in order to facilitate the operation.

  The steering rod 32 is a rod-like member that transmits the rotation of the steering wheel 31 to the rear wheel 12, and is arranged to extend in the vertical direction. The steering rod 32 is supported by the vehicle body 10 and the gear case 40 so as to be rotatable about the major axis. As described above, the steering wheel 31 is attached to the upper end of the steering rod 32 (the upper end in FIG. 2). On the other hand, a first steering gear 33A is disposed at the lower end of the steering rod 32 (the lower end in FIG. 2). A second steering gear 33B is disposed on the steering rod 32 above the position where the first steering gear 33A is disposed (see FIG. 3).

  As shown in FIG. 3, the first steering gear 33 </ b> A is a gear such as a spur gear that is fixed to the steering rod 32 and transmits the rotation of the steering rod 32 to the rear wheel 12 via the ring gear 34. The ring gear 34 is a gear such as a spur gear that is fixed to the drive unit including the drive motor 35 and the rear wheel 12 coaxially with the rotation shaft at the time of steering and meshed with the first steering gear 33A. The ring gear 34 is a gear having a larger diameter than the first steering gear 33A.

  Similarly to the first steering gear 33A, the second steering gear 33B is a gear such as a spur gear that is fixed to the steering rod 32 and transmits the assist torque generated by the assist motor 37 to the steering rod 32. Here, the assist torque generated by the assist motor 37 assists the steering torque necessary for the driver to steer the rear wheel 12, and enables the rear wheel 12 to be steered with less force. is there.

  The first assist gear 36A, the second assist gear 36B, and the third assist gear 36C are gears such as a spur gear that transmits the assist torque described above to the second steering gear 33B. The first assist gear 36A and the second assist gear 36B are fixed to the same shaft, and the first assist gear 36A is engaged with the second steering gear 33B. The third assist gear 36C is fixed to an output shaft of the assist motor 37 or a shaft that is rotationally driven by the assist motor 37, and meshed with the second assist gear 36B.

  The gear case 40 includes a steering rod 32 to which the first steering gear 33A and the second steering gear 33B are fixed, a shaft to which the first assist gear 36A and the second assist gear 36B are fixed, a third assist gear 36C, and a drive. The drive part which consists of the motor 35 and the rear-wheel 12 is supported so that rotation around each rotating shaft line is possible. Further, the gear case 40 is attached with the assist motor 37 and the steering angle sensor unit 50, and is supported by the suspension mechanism 60 so as to be movable in the vertical direction with respect to the vehicle body 10 (FIG. 2). reference).

  As shown in FIGS. 4A and 4B, the gear case 40 is formed with a projecting portion 41 to which the steering angle sensor unit 50 is attached and a machining surface 42 obtained by cutting an end of the projecting portion 41. Has been. In the present embodiment, the protrusion 41 and the machining surface 42 are an angle between the inter-axis distance L connecting the rotation axis 34C of the ring gear 34 and the rotation axis 50C of the steering angle sensor unit 50 and the longitudinal direction of the vehicle body 10. Is provided at a position where the predetermined angle α is less than 45 °.

  The protruding portion 41 is a member formed integrally with the gear case 40, and is formed to protrude toward the rear of the vehicle body 10 from the rear end portion of the gear case 40. The processed surface 42 is a flat surface formed at the rear end of the protrusion 41 and is a surface extending in the left-right direction and the up-down direction of the vehicle body 10. In other words, the plane is a plane whose normal line is parallel to the front-rear direction of the vehicle body 10. In the present embodiment, the processed surface 42 is a surface whose angle intersecting the direction of the above-described inter-axis distance L is less than ± 45 °.

  As shown in FIGS. 4 and 5, the steering angle sensor unit 50 is mainly composed of a sensor main body 51 that is a casing housing a potentiometer, and a sensor-side gear 52 that meshes with the ring gear 34. .

  The sensor main body 51 is mainly provided with an attachment surface 53 that comes into contact with the processing surface 42 and a through hole 54 through which a fastening member 55 such as a bolt that fixes the steering angle sensor unit 50 to the processing surface 42 is inserted. It has been. In the present embodiment, description will be made by applying to an example in which the sensor body 51 is provided with four through holes 54. These through-holes 54 are holes extending in the front-rear direction of the vehicle body 10 and have a diameter that ensures a predetermined gap between the through-holes 54 and the fastening member 55 to be inserted.

  The sensor-side gear 52 is a gear such as a spur gear fixed to the rotary shaft of the potentiometer extending from the sensor main body 51, and transmits the rotation of the ring gear 34 to the potentiometer housed in the sensor main body 51.

  Here, since the processed surface 42 is a surface formed by cutting, as shown in FIGS. 4A and 4B, it is easy to ensure the positional accuracy of the vehicle body 10 in the front-rear direction in the gear case 40. Become. Since the steering angle sensor unit 50 is directly attached to the machining surface 42, it is easy to ensure the positional accuracy of the rotation axis 50C of the steering angle sensor unit 50 in the front-rear direction with respect to the gear case 40. In other words, it becomes easy to ensure the accuracy of the distance x in the front-rear direction of the rotation axis 50C of the steering angle sensor unit 50 with respect to the rotation axis 34C of the ring gear 34 where the positional accuracy is ensured by the cutting surface of the same gear case 40.

  On the other hand, the distance y in the left-right direction of the rotation axis 50C with respect to the rotation axis 34C is less accurate than the distance x. However, since the angle α is less than 45 °, the portion Ly corresponding to the distance y in the inter-axis distance L is shorter than the portion Lx corresponding to the distance x. Will be affected by the accuracy of the distance x.

  Note that the accuracy of the inter-axis distance L increases as the proportion of the portion Lx for which it is easy to ensure the accuracy increases. Therefore, the accuracy is highest when the inter-axis distance L is occupied only by the portion Lx. This means a case where the front-rear direction of the vehicle body 10 and the inter-axis distance L are parallel (matched) as shown in FIG.

  Further, when the angle of the inter-axis distance L with respect to the front-rear direction of the vehicle body 10 exceeds 45 °, the inter-axis distance L is obtained by rotating the direction of the machining surface 42 by 90 ° as shown in FIG. Can be ensured.

  According to the forklift 1 having the above-described configuration, the steering angle sensor unit 50 is directly attached to the machining surface 42 provided in the gear case 40 that holds the first steering gear 33A, the ring gear 34, and the like. The distance L between the shafts can be kept within a desired range. Therefore, it is possible to suppress the deterioration of the measurement accuracy of the steering angle sensor unit 50 and to suppress the occurrence of failure.

  In other words, by directly attaching the steering angle sensor unit 50 having the sensor side gear 52 to the machining surface 42 of the gear case 40, the same as the first steering gear 33A and the ring gear 34 held by the gear case 40 with high relative position accuracy. In addition, the sensor-side gear 52 can also be arranged with high relative position accuracy with respect to the ring gear 34. In other words, the inter-axis distance L between the sensor side gear 52 and the ring gear 34 can be maintained with high accuracy.

  Conventionally, when the steering angle sensor is attached to the gear case 40, a configuration has been adopted in which the attachment position of the steering angle sensor can be adjusted using a bracket. That is, conventionally, it has been common knowledge to provide a mechanism for adjusting the mounting position of a bracket or the like and ensure the accuracy of the mounting position of the steering angle sensor by adjustment.

  The inventor of the present application paid attention to the fact that the gear case 40 that rotatably supports the first steering gear 33A, the ring gear 34, and the like is originally a member with high required accuracy. That is, in the gear case 40 that supports the first steering gear 33A, the ring gear 34, and the like that need to maintain the center distance with high accuracy, the position and shape of the supporting portion are formed with high accuracy. The gear case 40 is provided with a portion to which the steering angle sensor is directly attached as a mechanic surface formed with a position and a shape with high accuracy, similar to a portion supporting the first steering gear 33A, the ring gear 34, and the like. It came to create invention. According to the present invention, the steering angle sensor can be attached with high accuracy without adjusting the attachment position, and an adjustment mechanism that has been conventionally considered common sense can be dispensed with. Furthermore, it is possible to attach the steering angle sensor with high accuracy while reducing the number of parts and reducing the attaching work.

  Since the steering angle sensor unit 50 is attached in a state where the steering angle sensor unit 50 is in contact with the machining surface 42 of the gear case 40, the steering angle sensor unit 50 is displaced relative to the ring gear 34 that has been aligned when the steering angle sensor unit 50 is installed. Can be prevented from occurring. Further, even when the steering angle sensor unit 50 is removed and attached at the time of maintenance work or the like, the sensor side gear can be simply attached by attaching the steering angle sensor unit 50 to the processing surface 42 in contact with the steering angle sensor unit 50. The distance L between the shafts 52 and the ring gear 34 can be kept within a desired range.

  The machining surface 42 is a surface that intersects the above-described direction of the inter-axis distance L, preferably a surface that has an intersecting angle of less than ± 45 °, more preferably a surface that is orthogonal, so that the inter-axis distance L can be set to a desired value. It becomes easier to fit within the range.

  Further, instead of defining the orientation of the machining surface 42 using the direction of the inter-axis distance L as described above, the orientation of the machining surface 42 may be prescribed using the front-rear direction or the left-right direction of the forklift 1, The direction of the machining surface 42 may be defined using the rotation axis along which the rear wheel 12 rotates by steering, that is, the direction of the rotation axis 34C of the ring gear 34.

  Further, compared to the case where the steering angle sensor unit 50 is attached to the gear case 40 via a bracket, the bracket and other parts such as a fastening member for fixing the bracket can be eliminated, so that the forklift 1, more specifically, The manufacturing cost of the steering device 30 of the forklift 1 can be reduced.

  Further, by engaging the sensor-side gear 52 with the ring gear 34, the above-described condition of the inter-axis distance between the sensor-side gear 52 and the ring gear 34 can be relaxed. In other words, the predetermined range can be expanded.

  That is, the ring gear 34 is a gear having a larger diameter than the first steering gear 33A, the other ring gears 34, and the like, so that the gear ratio between the sensor side gear 52 and the ring gear 34 can be maximized. When the gear ratio is large, the backlash between the two gears necessary for keeping the phase error in the sensor-side gear 52 having a small diameter within a predetermined range can be increased as compared with the case where the gear ratio is small. In other words, it is easy to suppress a decrease in measurement accuracy in the steering angle sensor unit 50.

  Further, by directly attaching the sensor main body 51 to the machining surface 42, the steering angle sensor unit 50 can be easily attached and detached as compared with the case where the sensor-side gear 52 is attached to the machining surface 42. For example, the steering angle sensor unit 50 can be easily removed and attached during maintenance work.

  In order to attach and fix the sensor main body 51 to the processing surface 42 by the fastening members inserted into the plurality of through holes 54, the direction in which the through holes 54 extend is set to the direction orthogonal to the processing surface 42, so that the center distance can be set to a desired value. It becomes easier to fit within the range.

  Further, by forming the machining surface 42 on the projecting portion 41 provided on the gear case 40, it is possible to facilitate the attaching and detaching operations of the steering angle sensor unit 50. Furthermore, compared with the case where the protrusion part 41 is not provided, the area | region which can arrange | position the steering angle sensor part 50 can be expanded.

  As in the above-described embodiment, the gear with which the sensor-side gear 52 is engaged may be the ring gear 34, the second assist gear 36B as shown in FIG. 7, or the first assist. The gear 36A and the third assist gear 36C may be used and are not particularly limited.

  In this case, as shown in FIG. 8, the sensor-side gear 52 has a bearing 43 on a surface 43 that has been cut in the gear case 40, like the first assist gear 36A, the second assist gear 36B, the third assist gear 36C, and the like. 56 to be held. Therefore, compared with the case of the above-described embodiment in which the sensor body 51 is attached to the machining surface 42, the accuracy of the relative position with the second assist gear 36B and the like meshed with the sensor side gear 52, particularly the inter-axis distance L. It becomes easy to ensure accuracy.

  DESCRIPTION OF SYMBOLS 1 ... Forklift, 12 ... Rear wheel (steering wheel), 31 ... Steering wheel (steering part), 33A ... First steering gear (first gear), 34 ... Ring gear (second gear), 40 ... Gear case, 41 ... Projection , 42 ... machining surface, 50 ... steering angle sensor part, 51 ... sensor main body, 52 ... sensor side gear, 54 ... through hole, 55 ... fastening member

Claims (5)

A first gear to which a steering operation by the driver is transmitted from the steering unit;
A second gear that is rotationally driven by the first gear;
A gear case for rotatably holding the first gear and the second gear;
A steering angle sensor unit that is directly attached in contact with a machining surface provided in the gear case and measures a steering angle of a steered wheel by rotation of a sensor side gear meshed with the second gear;
The forklift characterized by being provided. 2. The forklift according to claim 1 , wherein an angle formed by a direction of an inter-axis distance between the second gear and the sensor-side gear and a normal direction of the machining surface is less than 45 degrees .   3. The forklift according to claim 1, wherein the steering angle sensor unit has a sensor main body attached to the processing surface, and the sensor-side gear attached to the sensor main body. The forklift according to claim 2, wherein a normal line direction of the machining surface is parallel to a longitudinal direction of the vehicle body . The outer surface of the gear case is provided with a protruding portion that protrudes integrally toward the outer direction,
The forklift according to any one of claims 1 to 4, wherein the projecting surface is provided on the projecting portion.

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