JP4745063B2 - Small crawler tractor - Google Patents

Description

  The present invention includes a hydraulic continuously variable speed turning pump (hereinafter also referred to as an HST turning pump) and a hydraulic continuously variable speed turning motor (hereinafter also referred to as an HST turning motor), and rotational driving of a steering wheel. It is related with the small crawler type tractor which can control the movable swash plate of the HST turning pump.

  FIG. 11 is a perspective view of a conventional small wheel tractor 97. The tractor 97 is a rear-wheel drive four-wheel vehicle, and a work machine is generally attached to the rear part of the tractor. However, since the wheel-type tractor 97 has a high ground pressure, the traveling performance on soft or rough terrain may not be sufficient, and particularly in the case of a small tractor, the traction force may not be sufficient due to its small size. In such a case, if the wheel-type tractor 97 can be improved to a small crawler tractor, the contact pressure can be reduced, so that it is possible to improve the running performance on soft or rough terrain, and at the same time, the traction force can be increased.

  As such a technique, for example, there is one that improves a new small crawler tractor by sharing a steering mechanism of a wheel tractor (Patent Document 1). The patent document 1 describes the difference between the crawler type and the wheel type turning mechanism, that is, when the wheel type tractor is modified to the crawler type, the brake device on one side is operated by depressing either the left or right brake pedal inside the turning. It was made in view of the fact that the turning operability was not good if the driving sprocket on one side was braked and the crawler inside the turning was decelerated to turn the vehicle body. The purpose of this invention is to reduce the cost by making it possible to turn the vehicle body of a small crawler tractor and by sharing parts using the steering mechanism provided in the wheel tractor.

  A wheeled work vehicle can run if the wheel is in contact with the ground even if the balance is somewhat poor, whereas a crawler type work vehicle may have insufficient traction because the front end of the crawler is lifted. Moreover, since the small crawler type tractor is mainly used for wet fields, it is necessary to set a high ground clearance. A technique for adjusting the tractor front-rear balance and ground clearance with a simple and inexpensive configuration has already been disclosed (Patent Document 2). The patent publication 2 discloses a tractor including a left and right crawler type traveling device in which a crawler is mounted between a drive sprocket and a driven idler, and a crawler frame that supports the drive sprocket and the driven idler is provided as a vehicle frame. On the other hand, a small crawler tractor is disclosed in which the attachment position can be adjusted in the front-rear direction and / or the vertical direction. The small crawler tractor disclosed in Patent Document 2 is presumed that the tractor portion is intended for a medium-sized or large-sized tractor, and the front end of a support member for mounting a crawler frame that supports a drive sprocket and a driven idler to a vehicle However, it is attached to the lower part of the tractor in front of the tip of the crawler type traveling device.

  On the other hand, a technique for simplifying the drive system of a small crawler tractor and improving turning performance has been developed particularly for medium and large tractors (Patent Document 3). For example, Patent Document 3 discloses a front wheel drive crawler tractor in which a hydraulic continuously variable speed turning mechanism (turning HST mechanism) for turning the airframe is connected to a drive system behind a forward / reverse switching mechanism for moving the airframe back and forth. A small crawler tractor is disclosed in which the turning HST mechanism is divided into a variable displacement pump and a constant displacement motor, and the constant displacement motor is connected to the input shaft of the planetary gear type differential mechanism. This tractor is connected to the variable displacement pump with the output after the sub-shift of the traveling speed change mechanism, and makes the turning radius constant by making the vehicle speed and the rotation of the steering motor proportional to each other. It can be secured. Note that the amount of oil discharged from the steering pump described in Patent Document 3 is controlled by both the rotational driving force of the steering and the input by the auxiliary transmission lever.

In addition, the mission structure and axle case are integrated as a compact crawler type tractor with improved work structure that is lightweight, simple, low cost, and has a good balance between front and back and easy handling even when the overall length is short. There is also disclosed a front-wheel drive small crawler tractor in which a transmission case is supported by a front and rear connection frame that is horizontally mounted between a pair of left and right crawler traveling devices, and an axle case is disposed in front of the connection frame. (Patent Document 4).
JP 2000-159143 A JP 2002-145134 A JP 2004-17841 A JP 2004-66913 A

  As described above, since the small crawler tractor has a low ground pressure, it is suitable for work in a wet field and can increase the traction force of the work implement. However, as shown in Patent Document 1, the driving of the wheel tractor is simply performed. If the wheel is used as a drive sprocket, it may not be possible to secure a ground clearance suitable for working in wet fields. In this regard, in the method of Patent Document 2, there are many fixing points and the operation is complicated.

  Even in the case of a small crawler tractor, it is preferable to ensure an excellent operation feeling as in the case of a medium or large-sized small crawler tractor. However, the small crawler tractors described in Patent Document 3 and Patent Document 4 are front wheel drive systems in which a front axle case is provided separately from the transmission in the lower front part of the engine, and the rear wheel drive system is its structure. Is different. Accordingly, it is not easy to manufacture a small rear wheel drive small crawler tractor at low cost by using the basic structure of a small rear wheel drive wheel tractor.

  Further, when the vehicle is turned by the rotational drive of the steering, the driving operability is excellent if the turning radius is constant without depending on the change of the sub-shift speed.

  Therefore, the present invention utilizes the structure of a small wheel tractor driven by a rear wheel as much as possible, can secure a ground clearance suitable for a wet field, obtains an excellent operation feeling by the rotational driving force of the steering wheel, and is used for turning HST. An object of the present invention is to provide a small crawler tractor that can easily adjust the output of a pump.

  The present inventors have provided a steering hydraulic speed change mechanism that turns the airframe in response to a rotational drive of the steering, an output shaft of a steering cam mechanism that outputs the rotational drive of the steering, and a steering hydraulic speed change mechanism. We found that by connecting the trunnion arm of the hydraulic continuously variable speed turning pump that we configure with a rod, we can manufacture a small crawler tractor at low cost by sharing the basic structure of the wheel type tractor, and also maintain the minimum ground clearance high, The present invention has been completed.

  According to the present invention, by connecting the trunnion arm of the HST turning pump and the output shaft of the steering cam mechanism with the rod, the amount of oil discharged from the HST turning pump, that is, the output of the HST turning motor is simplified with a simple structure. Can be adjusted. When the HST turning pump is arranged at the side of the transmission, the minimum ground clearance can be maintained high, and a steering cam mechanism can be arranged in front of the HST turning pump.

  According to the present invention, since the rotational drive of the steering is transmitted to the input shaft of the steering cam mechanism through the universal joint, the steering can be easily divided into a plurality of parts, and maintenance is easy.

  The small crawler tractor of the present invention can be manufactured using a common part provided in the wheel tractor, and can be manufactured at low cost.

A first aspect of the present invention includes a crawler frame that rotatably supports a driven idler at both ends, and a drive sprocket attached to a rear axle, and the crawler is wound between the driven idler and the drive sprocket. In a small crawler tractor equipped with a crawler type traveling device at the lower part of the upper vehicle body , a steering cam mechanism is arranged in front of the HST pump on the side of the transmission, and the pump is a steering arm that outputs the rotation of the steering handle. A small crawler tractor characterized in that the back-and-forth motion and the circular motion of the trunnion arm of the pump are interlocked . The HST turning pump in the present invention is an HST pump used for turning, and the HST pump has a charge pump and a movable swash plate, and compresses hydraulic fluid sent from the charge pump. The flow path is changed according to the inclination direction of the movable swash plate, the flow rate is increased or decreased according to the inclination angle, and output to the hydraulic motor. The HST turning motor is an HST motor used for turning. The motor converts the energy of hydraulic oil discharged from the HST pump into rotational energy and outputs it.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. 1 is a side view of a small crawler tractor according to an embodiment of the present invention, FIG. 2 is a perspective view of a traveling portion of the tractor, FIG. 3 is a sectional plan view of the tractor, and FIG. 4 is a drive portion of the tractor. 5 is a diagram showing a differential structure of the tractor, FIG. 6 is a skeleton diagram in which a throttle is attached to the hydraulic system of the HST turning mechanism in the tractor shown in FIG. 1, and FIG. 7 is an HST in the tractor shown in FIG. FIG. 8 is a skeleton diagram in which DRV is attached to the hydraulic system of FIG. 6, FIG. 9 is a perspective view of the frame structure of the crawler traveling device of the small crawler tractor of the present invention, and FIG. FIG. 11 is a perspective view showing a conventional wheel type tractor, and FIG. 12 is a steering handle and HST swivel, illustrating the ratio of the ground contact length (L2) of the crawler travel device to the total length (L1) of FIG. Partial view of the connection of the trunnion arm of the pump, Fig. 13 is a view showing the steering cam mechanism.

(1) Airframe As shown in FIG. 1, the small crawler tractor (airframe 1) of the present invention includes an upper vehicle body 90 and a crawler type traveling device 80 positioned therebelow. A bonnet 2 that covers (not shown) and an operation cabin 4 that controls the airframe 1 disposed behind the bonnet 2 are disposed. The driving cabin 4 is provided with a steering handle 9 for controlling the operation of the airframe 1. A seat 8 is provided behind the operation handle 4, and a main shift for operating the airframe and raising / lowering the work equipment is provided on the left and right sides of the seat 8. A lever (not shown), an auxiliary transmission lever (not shown), a PTO operation lever (not shown), and the like are provided. The machine body 1 can have the work machine 6 attached to the rear part thereof via a three-point support device.

  As shown in FIG. 1, the crawler type tractor according to the present invention has a drive sprocket on which a driven idler is rotatably supported at both ends of a crawler frame and is mounted on a rear axle. The drive sprocket is fixed to the crawler frame. A crawler type tractor for driving a rear wheel, in which a crawler type traveling device in which a crawler is wound between the vehicle and the drive sprocket is provided at the lower part of the upper vehicle body. Since the driven idlers are arranged at both ends of the flora frame, the driving sprocket is arranged at the upper portion of the driven idler, and a high ground clearance of the driving sprocket can be ensured.

  As shown in FIG. 2, the crawler type traveling device 80 includes two left and right crawler frames 81L and 81R extending in the traveling direction, and two front and rear side frames 82 that connect the crawler frames 81L and 81R. 83, driven idlers 85R and 85F are rotatably supported at the front and rear ends of the crawler frames 81L and 81R, respectively, and a plurality of equalizer wheels 86 are rotated between the two driven idlers 85R and 85F. It is configured to be freely supported. A driving sprocket 60 is disposed above the two driven idlers 85R and 85F and the equalizer wheel 86. The driving sprocket 60 is the apex, and a line connecting the two driven idlers 85R and 85F is the bottom. A crawler belt 95 is wound in a triangular shape.

(2) Power transmission mechanism The small crawler tractor according to the present invention includes a gear-switching traveling speed change mechanism that shifts traveling by changing gears, and a steering HST turning pump for turning the airframe in the drive system and the HST. A hydraulic speed change mechanism including a turning motor is connected.

  For example, as shown in FIG. 3, the driving force from the engine 3 is shifted by a main auxiliary transmission 39 that is a gear-switching traveling transmission mechanism disposed in the transmission case 23, and then the left and right rear axle cases 40L. , 40R, the axles 59L, 50R that drive the drive sprockets 60L, 60R of the crawler type traveling device 80 are rotated. Note that the hydraulic speed change mechanism may be connected to the front or back of the forward / reverse switching mechanism 7 for moving the body 1 forward and backward. In FIG. 3, the HST turning pump 72 and the HST turning motor 73 are arranged in the drive system behind the forward / reverse switching mechanism 7, respectively, and the side of the mission case 23 and the upper part of the differential mechanism 50 </ b> L in the mission case 23. Provided.

  As shown in FIG. 4, the output from the engine 3 is input from the output shaft 31 to the forward / reverse switching mechanism 7 via the clutch housing 5. In the forward / reverse switching mechanism 7, the gear 33 of the output shaft 31 and the forward gear 32 provided on the main shaft 37 mesh with each other to advance the machine body 1, while the reverse gear provided on the gear of the output shaft 31 and the main shaft 37. The gear 34 meshes with the counter gear 35 of the counter-counter shaft 35 for reverse travel, thereby moving the machine body 1 backward. The power passing through the forward / reverse switching mechanism 7 is transmitted to the main / sub transmission 39 through the main shaft 37. The main shaft 37 and the main transmission shaft 41 are connected via four main transmission gears 42 having different numbers of teeth on the main transmission shaft 41 and a gear 66 of the main shaft 37, for example, in the case of four main transmissions. Is done. The main transmission gear 42 is loosely fitted on the main transmission shaft 41. When any one of the four main transmission gears 42 is selectively fixed to the main transmission shaft 41 by a main transmission lever (not shown), the selected main transmission gear 41 is selected. The main transmission shaft 41 is driven to rotate according to the number of teeth of the transmission gear 42.

  This driving force is transmitted from the two gears 62 fixed to the main transmission shaft 41 to the auxiliary transmission shaft 45 via the auxiliary transmission gear 46. In the case of two sub-speeds, two sub-transmission gears 46 having different numbers of teeth are slidably formed on the sub-transmission shaft 45, and these two gears 46 are connected to the sub-transmission shaft by a sub-transmission lever (not shown). The power after the sub-shift is obtained by sliding back and forth on 45 and selectively meshing with any gear 62 on the main transmission shaft 41. The power after the sub-shift is changed from the front-rear direction to the left-right direction via the bevel gear 47 at the rear end of the sub-transmission shaft 45 and input to differential mechanisms 50L and 50R described later. In the present invention, it is preferable that a steering hydraulic transmission mechanism for turning the airframe is connected to a drive system behind the forward / reverse switching mechanism for moving the airframe back and forth. As a result, the steering handle 9 does not rotate backwards even when moving backward.

  On the other hand, the rotational power after the sub-shift is input to the HST turning pump input shaft 63 by driving the belt 65 after passing through the plurality of counter shafts 61 via the gear 64. By transmitting from the counter shaft 61 via a belt or the like, the position of the HST turning pump can be arranged at an arbitrary position. For this reason, the ground minimum height of the airframe 1 can be increased by disposing the HST turning pump 72 that was conventionally disposed at the lower part of the mission case 23 at the side of the mission case 23.

(3) Differential Mechanism As shown in FIG. 5, the driving force of the auxiliary transmission shaft 45 rotates the pinion shaft 22 via the bevel gear 47 and the bevel gear 21 meshing with the bevel gear 47. The left and right gears 25L and 25R fixed at both ends of the pinion shaft 22 mesh with the gears 27L and 27R fixed at one end of the left and right input shafts 20L and 20R, and the rotation of the pinion shaft 22 The input shafts 20L and 20R are distributed.

  The rotations of the left and right input shafts 20L and 20R are input to the sun gears 51L and 51R of the left and right differential mechanisms 50L and 50R. The differential mechanisms 50L and 50R include sun gears 51L and 51R fixed to the sun gear input shafts 20L and 20R, and planetary gears 53L and 53R provided around the sun gears 51L and 51R so as to freely rotate and revolve. The planetary gears 53L, 53R are supported by the sun gear input shafts 20L, 20R and the axles 59L, 59R. The carriers 55L, 55R are rotatably fitted to the outer periphery of the carriers 55L, 55R. Carrier gears 56L and 56R are formed. The planetary gears 53L and 53R mesh with drive output gears 58L and 58R fixed to the left and right drive output shafts 59L and 59R, and the drive output shafts 59L and 59R are rotated by the rotation of the drive output gears 58L and 58R. The sprockets 60L and 60R fixed to the other end are rotated.

  On the other hand, the differential mechanisms 50L and 50R introduce the output of the HST turning motor 73 in addition to the driving force of the auxiliary transmission shaft 45. The HST motor output gear 38 is rotationally driven by the output of the HST turning motor 73, and the two right and left reverse gears 52L and 52R meshing with the HST motor output gear 38 are reversely rotated. The reversing gears 52L and 52R are fixed to one ends of the left and right turning drive shafts 43L and 43R, and are fixed to the other ends of the turning drive shafts 43L and 43R via the turning drive shafts 43L and 43R. The differential gears 44L and 44R are driven to rotate, so that the left and right differential gears 44L and 44R are rotated in reverse. The differential gears 44L and 44R mesh with the carrier gears 56L and 56R to rotate the left and right carriers 55L and 55R in reverse. The planetary gears 53L and 53R pivotally supported by the left and right carriers 55L and 55R revolve around the sun gears 51L and 51R, but the left and right drive output shafts 59L and 59R are differentially driven by the difference in revolution speed at this time. It is rotated and the body 1 is turned leftward or rightward. When the vehicle is traveling straight, the left and right drive sprockets 60L and 60R have the same rotation speed, and the vehicle body 1 is turned when the left and right drive sprockets 60L and 60R have different rotation speeds.

  The HST turning pump 72 and the HST turning motor 73 are connected by piping, and the output rotation speed of the HST turning motor 73 is controlled according to the discharge amount from the HST turning pump 72, and the HST turning motor 73 is turned on. The output of the motor 73 is synthesized by the differential device 50L, the drive sprockets 60L and 60R are differentially rotated, and the body 1 is turned.

(4) Adjustment of the output of the HST turning pump 72 A movable swash plate is arranged in the HST turning pump 72, and the flow direction of the hydraulic oil changes depending on the inclination direction, and the hydraulic oil pump is changed according to the inclination angle. Discharge amount fluctuates. The movable swash plate is interlocked with the trunnion arm of the HST turning pump 72, and the inclination direction and the inclination angle of the movable swash plate vary in accordance with the arc movement of the arm. The rotational direction and rotational driving force of the steering handle 9 are converted into a circular motion of the trunnion arm and output, and the inclination angle of the movable swash plate is changed in accordance with the amount of rotation of the steering handle 9.

  As shown in FIG. 12A, the steering structure has a steering shaft 125 extending from the steering handle 9 through the steering column 123, and at the lower end of the steering shaft 125, a universal joint 127, a bevel gear or the like is attached to the steering input shaft 129. It is connected. The rotational drive of the steering handle 9 is input to the steering cam mechanism 130 disposed below the driving cabin 4 via the steering shaft 125, and the rotational power is output to the output shaft such as the steering arm 140 in the steering cam mechanism 130. Is converted into a back and forth movement. The output shaft is connected to the trunnion arm 145 of the HST turning pump 72 by a rod 143, and the back-and-forth movement of the output shaft is input to the HST turning pump 72 through the rod 143 as an arc motion of the trunnion arm 145. The inclination direction and the inclination angle of the movable swash plate are changed.

  In the steering cam mechanism 130, as shown in FIG. 13, the left turning eccentric cam 131, the connecting member 133, the steering arm 140, and the right turning eccentric cam 132 pass through the steering input shaft 129, respectively. A left turning roller 137 is fixed to the upper portion of the connecting member 133, and the roller 137 is in contact with the left turning eccentric cam 131. Further, a right turning roller 135 is fixed to the lower portion of the terminal of the steering arm 140, and the roller 135 is in contact with the right turning eccentric cam 132. The connecting member 133 is fixed to the left turning eccentric cam 132 and the steering arm 140.

  When the steering handle 9 rotates to the right, the steering input shaft 129 rotates to the right by the rotation, and the right turning eccentric cam 132 of the steering cam mechanism 130 rotates to the right. The right turning eccentric cam 132 is in contact with a right turning roller 135 fixed to the end of the steering arm 140, and the right turning eccentric cam 132 is rotated via the right turning roller 135. The steering arm 140 is moved forward about the steering input shaft 129. On the other hand, when the steering handle 9 rotates counterclockwise, the steering input shaft 129 rotates counterclockwise by the rotation, and the counterclockwise eccentric cam 131 of the steering cam mechanism 130 rotates counterclockwise. The left turning eccentric cam 131 is in contact with the left turning roller 137, rotates the left turning roller 137 around the steering input shaft 129, and simultaneously rotates the connecting member 133 fixed to the roller 137. Let The connecting member 133 is connected to the steering arm 140, and moves the steering arm 140 to the rear of the fuselage in response to the rotation of the connecting member 133.

  The steering arm 140 and the trunnion arm 145 of the HST turning pump 72 are connected by a rod 143, and the trunnion arm 145 performs an arc motion corresponding to the moving motion of the steering arm 140 in the front-rear direction. Corresponding to this arc motion, the tilt direction and tilt angle of the movable swash plate of the HST turning pump 72 are changed. As described above, the flow direction of the hydraulic oil is reversed by the inclination of the movable swash plate, and thus the direction of the rotational drive of the HST turning motor is also reversed. Therefore, the turning direction of the steering handle 9 and the tilting direction of the movable swash plate are the same as the turning direction of the steering handle 9 and the tilting direction of the movable swash plate when the output of the HST turning motor 73 is combined in the differential 50L. Needs to be adjusted to accommodate.

  In the present invention, in order for the steering arm 140, which is the output arm of the steering cam mechanism 130, and the trunnion arm 145 to be connected by the rod 143, it is necessary that the steering cam mechanism and the HST turning pump be disposed in the front and rear. It is. In the steering hydraulic transmission mechanism of the present invention, the HST turning pump 72 and the HST turning motor 73 can be arranged separately, so that the HST turning pump 72 is arranged on the side of the transmission 23. The ground clearance can be kept high. If the steering cam mechanism 130 is disposed in front of the HST turning pump 72 on the side of the transmission 23, the trunnion arm 145 of the HST turning pump 72 and the steering arm 140 of the steering cam mechanism 130 are connected by the rod 143. be able to. Therefore, when the HST turning pump 72 is arranged on the right side of the transmission 23, the steering cam mechanism 130 is arranged below the right step of the driving cabin 4, and when the HST turning pump 72 is arranged on the left side of the transmission 23. The steering cam mechanism may be disposed below the left step of the driving cabin 4. At this time, the HST turning pump 72 is arranged so that the back-and-forth movement of the steering arm 140 that outputs the rotation of the steering handle 9 and the circular movement of the trunnion arm 145 of the HST turning pump 72 are linked.

  In order to arrange the steering cam mechanism 140 below the right or left step of the driving cabin 4, as shown in FIG. 12 (b), a steering shaft 125 and a steering input shaft 129 extending from the steering handle 9 are connected to a bevel gear. The steering shaft 125 is similarly divided into an upper steering shaft 125 ′ and a lower steering shaft 125 ″ in two upper and lower parts, which are connected by a bevel gear or a universal joint 127. When the rotational drive of the steering handle 9 is transmitted to the upper steering shaft 125 ′, the lower steering shaft 125 ″ and the steering input shaft 129 by the two universal joints 127, the steering shaft 125 ′ and the lower steering shaft 125 ″ Na Angle (.theta.1), and it is preferable that the lower steering shaft 125 "angle between the steering input shaft 129 and (.theta.2) substantially the same. Thereby, the upper steering shaft 125 ′, the lower steering shaft 125 ″, and the steering input shaft 129 can be moved at a constant speed.

  In the present invention, according to the above configuration, the discharge amount of the HST turning pump 72 is changed in accordance with the operation amount of the left and right turning of the steering handle 9, and the output of the HST turning motor 73 is controlled accordingly. The turning radius can be controlled according to the output.

(5) Restriction of hydraulic transmission mechanism and delay relief valve The crawler tractor 1 of the present invention is configured so that the turning HST pump 72 and the turning HST are separated when the turning HST pump 72 and the turning HST motor 73 are separately arranged. Rings 100a and 101a (throttle) or a delay relief valve may be disposed on the left pipe 100 and the right pipe 101 (piping) that connect the motor 73.

  FIG. 6 is a skeleton diagram showing a hydraulic system of a hydraulic transmission mechanism including a turning HST pump 72 and a turning HST motor 73. The turning HST pump 72 and the turning HST motor 73 are connected by two pipes of a pipe 100 and a pipe 101 to form a closed circuit. As the steering handle 9 is steered, the inclination angle of the movable swash plate fluctuates, and the direction of the pressure oil flowing in the closed circuit fluctuates in response to this fluctuation, and piping when turning right (or turning left) 100 is the discharge side and the pipe 101 is the suction side. In the left turn (or right turn), the pipe 100 is the suction side and the pipe 101 is the discharge side. In the present invention, diaphragms 100 a and 101 a such as a ring having an appropriate opening diameter are fixedly provided inside the middle of the middle portion of the pipe 100 or the pipe 101. When the steering handle 9 is steered clockwise (right direction) or counterclockwise (left direction), the tilt angle of the movable tilt plate linked to the trunnion arm varies according to the steer amount, and the tilt angle Correspondingly, the oil of the turning HST pump 72 whose discharge amount has been adjusted passes through the ring 100a (or 101a) in the pipe 100 (or pipe 101) and then flows into the turning HST motor 73.

  FIG. 7 shows changes over time in the hydraulic pressure when the throttles 100a and 101a are provided in the pipe 100 and the pipe 101 in FIG. 6 (Line 1) and not (Line 2). As shown in FIG. 7, in Line 2, the set pressure is adjusted at the elapsed time t <b> 1, but in Line 1, t <b> 2 is stabilized until the set pressure (P <b> 1) is stabilized by the surge pressure generated by the presence of the movable swash plate. It cost. Although the details of the early stabilization according to the present invention are unknown, it is considered that by providing the ring, the surge pressure can be prevented from flowing into the turning HST motor 73, and thus the time required for the hydraulic pressure to stabilize can be shortened. It is done. For this reason, since the output of the controlled turning HST motor 73 can be synthesized by the differential mechanism 50L, a smooth turning feeling can be obtained. Rings having different opening diameters can be attached to the pipe 100 and the pipe 101 in place of the rings 100a and 101a, and it is easy to freely change the diameter of the throttle according to the degree of the turning feeling of the airframe 1. it can. The throttles provided in the pipe 100 and the pipe 101 are not limited to the rings 100a and 101a having appropriate opening diameters, and the pipe diameters in the middle of the pipe 100 and the pipe 101 are reduced to appropriate diameters. May be used.

  In the present invention, a delay relief valve (DRV) can be used instead of the above-mentioned throttle. FIG. 8 shows a hydraulic system of a hydraulic transmission mechanism using such DRV. In FIG. 8, DRVs 100 b and 101 b are attached at the same positions where the throttles are attached to the pipe 100 and the pipe 101, respectively. The DRVs 100b and 101b are provided with relief springs and spools (not shown in detail). Pressure oil from the turning HST pump 72 is caused by fluctuations in the inclination angle of the movable swash plate as the steering handle 9 is steered. By retracting the spool against the elastic force of the relief spring in the DRV 100b or DRV 101b, the pressure oil in which the surge pressure is absorbed can be sent to the turning HST motor 73. Furthermore, the elastic force of the relief springs in the DRVs 100b and 101b can be changed to adjust the time for the surge pressure of the pressure oil to reach the peak. In other words, increasing the elastic force of the relief spring slows down the time to absorb the surge pressure of the pressure oil, and conversely decreasing the elastic force of the relief spring increases the time to absorb the surge pressure of the pressure oil. Can be adjusted. In addition, since an adjustment tool (not shown) for changing the elastic force of the relief spring is attached to the outside of the DRVs 100b and 101b, the elastic force of the relief spring can be easily adjusted from the outside.

  It should be noted that the above-described restrictor such as a ring and DRV are not limited to being attached to both the pipe 100 and the pipe 101 at the same time, and may be attached to only one of the pipe 100 or the pipe 101. Further, the attachment positions of these rings, DRVs, etc. are not limited to the vicinity of the center of the midway part of the pipe 100 and the pipe 101, and may be anywhere within the pipe 100 and the pipe 101 between the HST pump 72 and the turning HST motor 73. 6 and 8 show the variable displacement pump, in which two charge relief valves are arranged, the present invention is not limited to this, and a constant displacement pump may be used.

(6) Type of hydraulic transmission mechanism pump In the present invention, the type of HST turning pump 72 is not limited, but if a variable displacement pump is used, a pump discharge amount proportional to the power of the drive system can be obtained. The capacity of the HST turning pump 72 can be changed in response to the turning operation of the steering handle 9 by the driver, and the output of the HST turning pump 72 can be changed steplessly. In particular, a constant displacement motor is connected to the variable displacement pump, and the combined power of the main shift and the sub shift is introduced into the HST turning pump 72, so that the travel speed and the operation can be controlled by adjusting the discharge amount of the variable displacement pump 72. The turning radius can be made constant by proportionally rotating the direction motor.

  On the other hand, when the discharge amount by the variable displacement pump is changed, the rotational driving force of the HST motor output gear 38 of the HST turning motor 73 is changed, and the two left and right reverse gears 52L meshing with the HST motor output gear 38 accompanying the rotation. The rotation of 52R changes, and finally the rotational driving force of the differential gears 44L and 44R fixed to the other ends of the turning drive shafts 43L and 43R changes. For this reason, even if the traveling speed is the same, the turning radius of the airframe can be changed by changing the capacity of the HST turning pump relative to the capacity of the HST turning motor. For example, by reducing the capacity of the HST turning motor relative to the capacity of the HST turning pump, the turning angle of the steering wheel, for example, the turning radius of the fuselage can be increased (soft mode) even at the same traveling speed. The turning radius of the fuselage can be reduced (spin mode) by increasing the capacity of the HST turning motor relative to the capacity of the HST turning pump. When the variable displacement pump is used, the discharge amount can be switched by a mechanical method such as a manual lever provided on the seat or an electrical method such as a solenoid. According to these methods, operation can be performed without leaving the seat, and the turning radius can be easily changed. Therefore, when performing a pivot turn on a crawler tractor, the pivoting start steering angle can be set to be smaller or larger depending on the work situation by changing the turning mode such as the soft mode or the spin mode. It is possible to change.

  In order to input the power of the auxiliary transmission shaft to the input shaft 63 of the HST turning pump 72, the driving is not limited to the driving of the belt 65 but may be a chain or a gear. Further, if the HST turning motor connected to the HST turning pump 72 by piping is arranged at the upper part of the transmission 23, the oil stored in the transmission case 23 can be stored even when the HST turning motor 73 is repaired. The HST turning motor can be easily removed and removed from the HST turning motor 73 without maintenance, and the working efficiency is improved. Further, when the HST turning motor 73 is disposed on the upper part of the transmission case 23, particularly on the differential mechanism 50, oil leaking from the HST turning motor 73 can be directly flowed down to the differential mechanism.

  In the present invention, the power input to the HST turning pump 72 may be power from the main transmission shaft, power from the auxiliary transmission shaft, or both. When the power obtained by adding the main shift and the sub-shift of the drive system is introduced into the hydraulic continuously variable turning pump, the turning radius can be made constant by making the vehicle speed and the rotation of the steering motor proportional to each other. Therefore, it is preferable.

(7) Upper vehicle body and crawler type traveling device In the crawler type tractor of the present invention, it is preferable that the crawler frame of the crawler type traveling device is fixedly provided by the upper vehicle body and at least two support members. If fixed with such a small number of members, the left and right crawler type traveling devices can be easily attached to the upper vehicle body and separation is easy, and the weight balance can be changed due to an optional device added to the upper vehicle body. Accordingly, it can be easily moved back and forth.

  Since the fixed position between the upper vehicle body and the left and right crawler type traveling devices is determined by the weight balance with the upper vehicle body, when the upper vehicle body is small, a support member is provided on the pair of left and right crawler frames (81L, 81R). The upper vehicle body can be attached simply by mounting and fixing the upper vehicle body (90) via (87R, 87L, 84R, 84L). However, if only one location is fixed to one crawler frame, the entire weight of the crawler frame is applied only to that location and the rear balance is created, so that the front of the crawler floats when running on wet fields or when the work equipment is attached to the rear. Such problems may occur. Therefore, it is fixed by at least two support members. In this case, in the present invention, in addition to the fixing portion between the upper vehicle body and the crawler frame, the upper vehicle body is fixed to the upper vehicle body by a support member at the rear of the vehicle from the front end portion of the crawler type traveling device. Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 2002-2523, the upper vehicle body is fixed by a support member that extends to the front of the vehicle body rather than the crawler type traveling device. By adjusting the weight balance by devising the arrangement of the drive system and the like, it can be fixed to the upper vehicle body by a support member behind the front end of the crawler type traveling device. Moreover, since the center of gravity balance is excellent, it is possible to travel stably even if the crawler is short.

  In the present invention, the left and right crawler frames are fixed to the upper vehicle body 90 by at least two support members, respectively, and the fixed position is behind the vehicle from the tip of the crawler type traveling device 80. For example, as shown in FIG. 6, support members 87R, 87L, 84R, and 84L are arranged from the front and rear of the crawler frame 81L upward, and are fixed to the upper vehicle body 90, respectively. Although there is no limitation on the fixed position of the upper vehicle body 90, for example, the support members 87R and 87L7 can be fixed to the side surface of the clutch housing of the upper vehicle body 90, and the support members 84R and 84L are attached to the rear axle cases 40L and 40R. Can be fixed. The fixing location of the upper vehicle body is not particularly limited, but in the present invention, the fixed location between the support members 87R, 87L, 84R, 84L and the upper vehicle body 90 is from the tip of the crawler type traveling device 80 to the vehicle. Can be fixed to a structure such as a clutch housing disposed at the top of the crawler type traveling device 80 simply through a support member, and a special fixing point is provided at the lower part of the upper vehicle body. There is no need. For this reason, the total weight of the vehicle can be reduced.

  In addition, in the present invention, as shown in FIG. 10, the contact length (L2) of the crawler traveling device with respect to the total length (L1) of the upper vehicle body, that is, L2 / L1 is 0.5 or more. In the present invention, since the contact length of the crawler traveling device can be shortened within the above range, the turning operation is facilitated. In addition, space is secured at the front lower part of the vehicle body to prevent the entanglement of the field protrusions, so that the turning time is improved regardless of the state of the field scene, and a stable turning operation is ensured even in the corners of a narrow field. . In addition, since the contact length of the crawler traveling device is short, the total weight can be reduced. Since the total weight of the vehicle is reduced as described above, the contact pressure can be kept low even when the contact length of the crawler traveling device is short, and the turning performance can be improved. Note that the total length (L1) of the upper vehicle body does not include the length of the work implement attached to the front portion or the rear portion.

  In the crawler tractor of the present invention, the crawler frame is fixed to the upper vehicle body by fixing the support members (87R, 87L) to the upper vehicle body with bolts and the support members (84R, 84L) as shown in FIG. The rear axle cases 40L and 40R are preferably fixed with bolts. If it is a volt | bolt, it can attach simply, without using a new fixture.

(8) Others Deceleration is performed via a plurality of brake plates 29 provided at one end of the pinion shaft 22. When a brake pedal (not shown) is operated by a driver's operation, the brake arm 28 is rotated in conjunction with the brake arm 28, and a brake action is generated on the pinion shaft 22 along with the rotation of the brake arm 28 to decelerate the airframe 1. . In particular, the brake plate 29 is located at the right end of the pinion shaft 22, and a brake case (not shown) that accommodates the brake plate, a brake arm, and the like is replaced with a right rear axle case that accommodates the right differential mechanism. 40R can be integrated. When the HST turning motor 73 is positioned on the left rear axle case, the brake mechanism arranged in the right rear axle case 40R and the HST turning motor arranged in the left rear axle case 40L. The weight with 73 can be harmonized and the weight balance of the airframe 1 can be maintained.

  The work machine is driven through a PTO output shaft. As shown in FIG. 4, a part of the output of the engine 3 is connected from the forward / reverse switching mechanism 7 to the PTO counter shaft 49 via the PTO transmission gear 48 and transmitted to the PTO output shaft 91 at the rear of the machine body. .

  Although the present invention has been described with respect to a tractor as an example of a crawler type work vehicle, the present invention is not limited to this, and a crawler such as a combine that uses a crawler, a backhoe, a bulltozer, or the like as a construction work machine. It can be applied to any working machine equipped.

It is a side view which shows the small crawler type tractor as an example of the small crawler type tractor of this invention. It is a perspective view showing a perspective view of a run part in a small crawler type tractor of the present invention. It is a section top view of the small crawler type tractor of the present invention. It is a section side view of the drive part in the small crawler type tractor of the present invention. It is a figure which shows the differential structure of the small crawler type tractor of this invention. It is a perspective view of the frame structure of the crawler traveling device of the small crawler type tractor of the present invention. It is a graph which shows the hydraulic pressure of the HST turning mechanism in the tractor shown in FIG. It is a skeleton figure which attached DRV to the hydraulic system of Drawing 6. It is a perspective view of the frame structure of the crawler traveling device of the small crawler type tractor of the present invention. It is a figure explaining ratio of the contact length (L2) of a crawler traveling device to the full length (L1) of an upper body. It is a perspective view which shows the conventional wheel type tractor. 12 (a) is a partial side view showing the connection between the steering handle and the trunnion arm of the HST turning pump, and FIG. 12 (b) is a partial vertical side view. It is a figure which shows a steering cam mechanism.

Explanation of symbols

  1 Crawler tractor (vehicle), 2 bonnet, 3 engine, 4 cabin, 5 clutch housing, 6 working machine, 7 forward / reverse switching mechanism, 8 driver's seat, 9 steering handle, 20L, 20R input shaft, 21 bevel gear, 22 pinion Shaft, 23 Transmission case, 31 Output shaft, 37 Main shaft, 38 HST motor output gear, 39 Main auxiliary transmission, 40L, 40R Rear axle case, 41 Main transmission shaft, 42 Main transmission gear, 45 Sub transmission shaft, 49 PTO counter Shaft, 50L, 50R Differential mechanism, 58L, 58R Drive output gear, 59L, 59R Axle (axle), 60L, 60R Drive sprocket (sprocket), 61 Counter shaft, 63 Turning HST pump input shaft, 72 Turning HST pump 73 HST motor for turning, 80 Roller type traveling device, 81L, 81R crawler frame, 84 support member, 85 driven idler, 87 support member, 91 PTO output shaft, 95 crawler belt, 97 wheel type tractor, 100 left pipe, 101 right pipe, 100a, 101a ring 100b, 101b DRV, 123 Steering column, 125 Steering shaft, 125 'Upper steering shaft, 125 "Lower steering shaft, 127 Universal joint, 129 Steering input shaft, 130 Steering cam mechanism, 131 Left turning eccentric cam, 132 Right Rotating eccentric cam, 133 connecting member, 135 right turning roller, 137 left turning roller, 140 steering arm, 143 rod, 145 trunnion arm.

Claims (3)

A crawler type traveling device having a crawler frame that rotatably supports a driven idler at both ends and a driving sprocket mounted on a rear axle, and a crawler wound between the driven idler and the driving sprocket. In the small crawler tractor provided at the lower part of the vehicle body, the drive system of the small crawler tractor includes a hydraulic continuously variable turning pump for turning the body in response to the rotational drive of the steering and a hydraulic continuously variable speed turning motor. The steering hydraulic transmission mechanism is connected,
The hydraulic continuously variable speed turning pump is disposed on the side of the transmission,
The steering handle is connected to a steering cam mechanism via a steering shaft having a universal joint, and the steering cam mechanism is connected to a trunnion arm of the hydraulic continuously variable speed turning pump via an output shaft and a rod. , The steering cam mechanism is disposed in front of the hydraulic continuously variable speed turning pump,
A compact crawler-type tractor configured so that the forward / backward movement of the output shaft and the circular movement of the trunnion arm are linked via the universal joint in accordance with the steering operation.   2. The small crawler tractor according to claim 1, wherein power obtained by adding main transmission power and auxiliary transmission power of the drive system is introduced into the hydraulic continuously variable speed rotation pump. 3. The small crawler tractor according to claim 1, wherein the steering hydraulic speed change mechanism is connected to a drive system behind a forward / reverse switching mechanism for moving the airframe forward and backward.

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