JP2007216805A - Crawler type working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small crawler type tractor improved in a rectilinear propagating travelling property of a frame neutral at a steering position of a steering handle by using a structure of a small wheel type rear-drive tractor. <P>SOLUTION: A driving sprocket 60 is revolved by power from an HST pump 72 for revolution and an HST motor 73 for revolution, the HST pump 72 for revolution and the HST motor 73 for revolution are divided and arranged, and a steering arm 114 of the steering wheel 9 is furnished with a detector 106 to detect a steering position of the steering wheel 9 and a fixing mechanism 100 interlocked with this detector 106 and to fix this output shaft 73a on the output shaft 73a of the HST motor 73 for revolution. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a small crawler tractor in which a turning hydraulic transmission pump (hereinafter referred to as a turning HST pump) and a turning hydraulic transmission motor (hereinafter referred to as a turning HST motor) are arranged separately. More specifically, the present invention relates to a small crawler tractor or the like in which the output of a turning HST motor is input to a differential mechanism and has excellent turning feeling.

  FIG. 12 is a perspective view of a conventional small wheel tractor. This tractor is a rear-wheel drive four-wheeled vehicle. Generally, such a wheel-type tractor is lifted and driven by hydraulic pressure, gears, etc., a farming operation attachment, an attachment for paddy shaping, an attachment for soil disinfection, and a cultivation floor preparation Generally, work machines such as attachments for seeds, attachments for sowing seeds, and attachments for multi-work are attached. For this reason, wheel type tractors equipped with work implements tend to lose the balance between the front and rear of the fuselage, and tire contact pressure is high, so there are cases where running on soft and rough terrain is not sufficient, especially in the case of small tractors, Due to its small size, the traction force may not be sufficient. In such a case, if the wheel type tractor can be improved to a small crawler type 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 increase the traction force.

  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 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. This was made in view of the fact that the turning operability was not good if the driving sprocket on one side was braked to decelerate the crawler on the inside of the turn and the vehicle body was turned. An object of the present invention is to make it possible to turn the body of a crawler tractor and to reduce costs by sharing components using a steering mechanism provided in a 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 document 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 the crawler frame that supports the drive sprocket and the driven idler is 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 portion of a support member that attaches 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 in which a hydraulic transmission turning mechanism (hereinafter referred to as a 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. This is a crawler type tractor. The turning HST mechanism is divided into a variable displacement pump and a fixed displacement motor, and the auxiliary transmission gear transmission mechanism and the turning HST pump are not linked to each other and used as the input shaft of the planetary gear type differential mechanism. A small crawler tractor with a fixed capacity motor connected thereto is disclosed. 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.

  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 machine. If the driving wheel is used as a driving sprocket, it may not be possible to secure a ground clearance suitable for work in a wetland. In particular, since a small crawler tractor is required to adjust the left / right and up / down balance more strongly, it is convenient if such control can be adjusted more easily. In this case, as in Patent Document 2, a mounting hole is opened in the crawler frame, a mounting hole corresponding to the mounting hole is opened in the vehicle frame, and these are fixed by shifting in the front-rear and vertical directions. Then, there are many fixed parts, and operation is complicated. Moreover, since the small crawler type tractor is heavier than the wheel in the left and right crawler type traveling devices, the total weight tends to be heavy, and the need for weight reduction is strongly desired.

  In addition, 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 hydraulic transmission mechanism for steering that turns the aircraft, the forward / reverse switching mechanism that makes the aircraft move forward and backward, the variable displacement pump of the hydraulic transmission mechanism for turning, etc. that are used to improve the turning feeling are simply small. It is structurally difficult to divert to a crawler tractor. Particularly, 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 a 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.

Accordingly, a first object of the present invention is to provide a small crawler tractor that can be manufactured by utilizing as much as possible the structure of a small wheel tractor driven by a rear wheel.
In addition, in the conventional crawler type tractor, when the steering wheel steering position in the turning HST mechanism is neutral, the torque reaction force generated on the left and right crawlers due to obstacles and unevenness on the road surface when the aircraft is traveling straight ahead The differential mechanism is activated, and there is a problem that the vehicle cannot travel straight for a long distance.
Accordingly, a second object of the present invention is to provide a small crawler tractor that improves the straight traveling performance of the airframe when the steering position of the steering wheel is neutral.

  Therefore, the invention according to claim 1 has a crawler frame that rotatably supports the driven idler at both ends, a drive sprocket mounted on the rear axle, and a crawler belt between the driven idler and the drive sprocket. In the crawler type work vehicle provided with a crawler type traveling device wound around the upper vehicle body, the drive sprocket is turned by power from the turning HST pump and the turning HST motor, and the turning HST pump The turning HST motor is divided and arranged, a detecting means for detecting a steering position of the steering handle in a steering mechanism of the steering handle, and interlocking with the detecting means, the output shaft of the turning HST motor And a fixing mechanism for fixing the output shaft.

  The invention described in claim 2 is characterized in that an electromagnetic valve interlocked with the detection means is provided in the middle of a member for introducing charge pressure oil from a charge pump into the fixing mechanism.

  According to a third aspect of the present invention, when the steering mechanism is a steering position of the steering wheel including a play portion and a neutral position where the turning HST motor does not operate. The output shaft of the turning HST motor is fixedly operated.

  The invention described in claim 4 is characterized in that the fixing mechanism is operated by an urging means and charge pressure oil from the charge pump.

  The invention according to claim 5 is characterized in that the electromagnetic valve opens when a steering position of the steering handle is a turning position for turning the airframe.

  According to the first aspect of the present invention, the crawler frame that rotatably supports the driven idler at both ends and the drive sprocket attached to the rear axle are provided, and the crawler belt is wound between the driven idler and the drive sprocket. In a crawler type work vehicle having a crawler type traveling device mounted on the lower part of the upper vehicle body, the drive sprocket is turned by power from the turning HST pump and turning HST motor, and the turning HST pump and turning HST motor And a detecting means for detecting the steering position of the steering handle in the steering mechanism of the steering handle, and the output shaft is fixed to the output shaft of the turning HST motor in conjunction with the detecting means. Since it has a fixed mechanism, it is for turning in conjunction with the steering position of the steering wheel. Fixing mechanism ST motor shaft can be a switch to operation or non-operation. Accordingly, a compact crawler tractor is provided that improves the straight traveling performance of the airframe when the steering position of the steering wheel is neutral.

  According to the second aspect of the present invention, since the electromagnetic mechanism that interlocks with the detecting means is provided in the middle of the member that introduces the charge pressure oil from the charge pump into the fixing mechanism, the steering mechanism is interlocked with the turning operation of the steering handle. Thus, charge pressure oil from the charge pump can be introduced into the fixing mechanism. Accordingly, it is possible to provide a small crawler tractor that can reliably switch between straight traveling and turning traveling of the airframe and that has improved safety.

  According to the third aspect of the present invention, the fixing mechanism turns when the steering position of the steering handle is a straight position of the airframe including the play portion and is a neutral position where the turning HST motor does not operate. Since the output shaft of the motor HST motor is fixedly operated, the rotation of the output shaft of the turning HST motor can be prevented by the traveling torque reaction force of the left and right crawlers. Therefore, it is possible to provide a small crawler tractor that prevents fine rotation of the output shaft of the turning HST motor and stabilizes the straight traveling accuracy when the vehicle is traveling straight.

  According to the fourth aspect of the invention, the fixing mechanism is operated by the urging means and the charge pressure oil from the charge pump. Therefore, the output HST motor output shaft for turning using the charge pressure oil from the charge pump. Can be fixed or unfixed. Accordingly, a turning HST motor output shaft fixing mechanism with a simple configuration can be provided.

  According to the fifth aspect of the present invention, the electromagnetic valve opens when the steering position of the steering handle is the turning position for turning the airframe, so that the turning is performed using the charge pressure oil from the charge pump. The HST motor output shaft can be unlocked. Therefore, it is possible to provide a turning HST motor output shaft fixing mechanism that is linked to the traveling system and has a simple configuration.

  In addition, according to the present invention, since the common part provided in the small wheel tractor is used, a small crawler tractor can be manufactured at low cost. In addition, it is possible to provide a small crawler-type tractor that has a larger force for towing a farm work machine than a wheel-type tractor and is excellent in running performance on soft or rough terrain.

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 type tractor according to an embodiment of the present invention, FIG. 2 is a perspective view of a crawler type traveling device in the tractor, FIG. 3 is a sectional plan view of the tractor, and FIG. 4 is a drive in the tractor. FIG. 5 is an enlarged sectional plan view of the vicinity of the differential mechanism in the transmission case.

  First, a schematic configuration of the crawler tractor 1 will be described. As shown in FIG. 1, a bonnet 2 that covers an engine 3 (not shown) is disposed in front of the vehicle 1, and a cabin 4 for operating the vehicle 1 or a not-shown lops frame is disposed behind the bonnet 2. . A steering handle 9 that controls the operation of the vehicle 1 is arranged in front of the cabin 4, and a driver's seat 8 is operated in the rear, and on the left and right of the driver's seat 8, the vehicle 1 is operated and the working machine 6 is raised and lowered. Various levers (not shown) such as a main transmission lever, a sub transmission lever, and a PTO operation lever are provided. In the unlikely event that the vehicle 1 rolls over, the cabin 4 including four safety frames for protecting the driver is formed so as to cover the entire driver seat 8. A step 10 for raising and lowering the driver's seat 8 is provided below the cabin 4. A work machine 6 that can be removed according to work is attached to the rear of the upper vehicle body 90, and the work machine 6 performs work such as plowing and rotary. Further, a pair of left and right crawler type traveling devices 80 for traveling the vehicle 1 are disposed below the upper vehicle body 90.

  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 side frames 82 and 83 connecting the crawler frames 81L and 81R. The driven idlers 85 are rotatably supported at the front and rear ends of the crawler frames 81L and 81R, respectively. Between the two driven idlers 85, four equalizer wheels 86 are rotatably supported. . The two driven idlers 85, the four equalizer wheels 86, and the drive sprocket 60 pivotally supported by the rear axle case 88 have a straight line connecting the two driven idlers 85 with the drive sprocket 60 at the top. The crawler type traveling device 80 is formed by winding the crawler belt 95 in a substantially triangular shape. The total length of the crawler type traveling device 80 is 50 to 55% of the length of the upper vehicle body 90.

  Two support members 87 are further provided upward from the front side frame 82, and the upper vehicle body 90 is secured by bolting the support members 87 to the side surfaces of the clutch housing 5 described later. And the crawler type traveling device 80 are connected. In addition, left and right rear axle cases 88L and 88R for supporting left and right axles (rear axles) 89L and 89R to which the left and right drive sprockets 60L and 60R are connected are provided at the rear portions of the crawler frames 81L and 81R. The left and right rear axle case stays 99L and 99R are integrally formed on the upper side.

  Hereinafter, the traveling system of the crawler tractor 1 of the present invention will be described. As shown in FIG. 3, the power from the engine 3 is shifted by the main / sub transmission 39 in the transmission case 23 via the clutch housing 5 and then input to the left and right differential mechanisms 50L and 50R. Then, the crawler type traveling device 80 is driven by the left and right drive sprockets 60L and 60R via the left and right axles 89L and 89R extended from the differential mechanisms 50L and 50R. Further, a turning hydraulic transmission mechanism (HST) pump 72 for turning the vehicle 1 described later is provided on the side of the mission case 23, and a turning HST motor 73 is provided above the differential mechanism 50L. Further, the differential mechanisms 50L and 50R can be switched left and right.

  A movable swash plate (not shown) in the turning HST pump 72 that is a variable displacement type is linked to the steering handle 9 via a sub-transmission arm (not shown), and the turning HST pump 72 according to the steering amount of the steering handle 9. Is adjusted, and the output rotation speed and rotation direction of the turning HST motor 73 are controlled in accordance with the discharge amount. Then, the output of the turning HST motor 73 and the output from the auxiliary transmission 39 are combined in a differential mechanism 50 described later, and the drive sprockets 60L and 60R are rotationally driven via the axles 89L and 89R.

  In the crawler tractor 1 according to the present invention, the turning HST pump 72 and the turning HST motor 73 are provided as described above. However, the turning HST pump 72 that is usually disposed in the lower portion of the transmission case 23 is used in the present invention. Can be secured in parallel with the mission case 23 to ensure a high minimum ground clearance. Further, since the turning HST pump 72 and the turning HST motor 73 are separate bodies, the turning HST motor 73 can be repaired by arranging the turning HST motor 73 above the mission case 23. The oil stored in the mission case 23 does not flow out of the turning HST motor 73, so that the turning HST motor 73 can be easily removed and maintained, and the working efficiency is improved. Further, by disposing the turning HST motor 73 on the upper part of the transmission case 23, particularly on the differential mechanism 50 described later, oil leaked from the turning HST motor 73 can be directly flowed down to the differential mechanism 50. it can.

  Next, the configuration of power transmission in the mission case 23 will be described. As shown in FIG. 4, the output shaft 31 of the engine 3 is input to the forward / reverse switching mechanism 7 via the clutch housing 5. In the forward / reverse switching mechanism 7, when the vehicle 1 moves forward, the output shaft 31 and the forward gear 32 mesh with each other. On the other hand, when the vehicle 1 moves backward, the output shaft 31 and the reverse gear 34 counter the counter counter 35 for reverse movement. By engaging through the gear 36, the vehicle 1 moves forward and backward.

  Then, power is transmitted from the forward / reverse switching mechanism 7 to the main auxiliary transmission 39 at the rear of the vehicle 1 through the main shaft 37. The main shaft 37 and the main transmission shaft 41 positioned above the main shaft 37 are connected via four main transmission gears 42 having different numbers of teeth (in the case of four main transmission gears). The main transmission gear 42 always meshes with the gear 66 on the main shaft 37 and rotates together. On the other hand, the main transmission gear 42 is loosely fitted on the main transmission shaft 41, and the main transmission shaft 41 is not rotated by the rotation of the main transmission gear 42. By selectively fixing any of the gears 42 on the main transmission shaft 41, the main transmission shaft 41 is driven to rotate according to the number of teeth of the main transmission gear 42 fixed on the main transmission shaft 41. .

  The main transmission shaft 41 that is rotationally driven in this way is located behind the main transmission shaft 41 and is connected to the auxiliary transmission shaft 45 from the two gears 62 fixed on the main transmission shaft 41 via the auxiliary transmission gear 46. Is transmitted to. On the auxiliary transmission shaft 45, two auxiliary transmission gears 46 having different numbers of teeth (in the case of two auxiliary transmission stages) are slidably formed. The auxiliary transmission lever (not shown) causes these two gears 46 to be slidable. The power after the sub-shift is obtained by sliding back and forth on the sub-transmission shaft 45 and selectively meshing with any of the gears 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 a bevel gear 47 located at the rear end of the sub-transmission shaft 45, and differential mechanisms 50L and 50R located behind the mission case 23 described later. Will be entered.

  A part of the output of the engine 3 is connected to the PTO countershaft 49 via the PTO transmission gear 48 from the forward / reverse switching mechanism 7 and transmitted to the PTO output shaft 91 at the rear of the vehicle 1. The power for driving the turning HST pump 72 is transmitted to the plurality of counter shafts 61 through the counter gear 64 fixed on the sub transmission shaft 45, and finally. It is transmitted to the input shaft 63 of the turning HST pump 72 by driving the belt. In particular, the power for driving the turning HST pump 72 is input from the counter shaft 61 to the turning HST pump 72 via the chain 65 or the like, so that the turning HST pump 72 can be arranged at an arbitrary position. It becomes possible. Therefore, the minimum ground clearance of the vehicle 1 can be increased by disposing the turning HST pump 72 that is conventionally disposed at the lower part of the transmission case 23 on the side surface of the transmission case 23.

  Next, the configuration of the differential mechanism 50 for turning the vehicle 1 will be described. As shown in FIG. 5, the power after the sub-shift in the front-rear direction is transmitted via the bevel gear 47 fixed to the rear end of the sub-transmission shaft 45 and the bevel gear 21 fixed to the center portion of the pinion shaft 22. Then, the rotation direction is changed to the left and right direction, and transmitted to the left and right differential mechanisms 50L and 50R described later. Gears 25L and 25R fixed to both left and right ends of the pinion shaft 22 drive the left and right input shafts 20L and 20R via gears 27L and 27R meshing with the gears 25L and 25R. The input shafts 20L and 20R rotationally drive sun gears 51L and 51R of the planetary gear mechanism 50 that is the differential mechanism 50. The planetary gear mechanism 50 outputs a differential rotation for turning.

  Further, the planetary gear mechanism 50 will be described in detail. The planetary gear mechanisms 50L, 50R include sun gears 51L, 51R fixed to the input shafts 20L, 20R, planetary gears 53L, 53R provided around the sun gears 51L, 51R so as to freely revolve, and the planetary gears 53L, It includes carriers 55L and 55R that rotatably support 53R and are freely loosely fitted to the input shafts 20L and 20R and the axles 89L and 89R. Further, carrier gears 56L and 56R are formed on the outer circumferences of the carriers 55L and 55R.

  Due to the configuration of the planetary gear mechanisms 50L and 50R, when the vehicle 1 goes straight, that is, when the rotations of the left and right drive sprockets 60L and 60R are equal to each other, the carriers 55L and 55R do not rotate and the planetary gear mechanism 50L. , 50R rotates on the respective shafts on the spot to rotate the drive sprockets 60L, 60R. As a result, the left and right drive sprockets 60L and 60R rotate in the same rotational speed and in the same rotational direction, respectively, and move the vehicle 1 straight. On the other hand, when the vehicle 1 turns, that is, when the left and right drive sprockets 60L and 60R have different rotation speeds, the carriers 55L and 55R are driven to rotate by a turning HST motor 73, which will be described later. The planetary gears 53L and 53R of 50L and 50R are revolved around the sun gears 51L and 51R.

  Then, in addition to the rotation of the sun gears 51L and 51R, the planetary gears 53L and 53R located between the sun gears 51L and 51R and the carriers 55L and 55R start to revolve around the sun gears 51L and 51R by the rotation of the carriers 55L and 55R. . At this time, when the rotation of the sun gears 51L and 51R and the rotation of the carriers 55L and 55R are in the same direction, the rotation sum of the rotation of the sun gears 51L and 51R and the rotation of the carriers 55L and 55R is the planetary gear 53L. The axle gears 58L and 58R are rotated through the self-revolution of 53R.

  On the other hand, when the rotation of the sun gears 51L and 51R and the rotation of the carriers 55L and 55R are different directions, the rotation difference between the rotation of the sun gears 51L and 51R and the rotation of the carriers 55L and 55R is the planetary gear 53L, The axle gears 58L and 58R are rotated through the self-revolution of 53R.

  Here, the rotation of the carriers 55L and 55R is rotationally driven by the turning HST motor 73. The turning HST motor 73 is rotationally driven as the steering handle 9 is steered as described above, and the turning HST motor 73 is driven. The rotation of the left and right reversing shafts 43L and 43R is reversely rotated via the left and right reversing gears 52L and 52R engaged with the output gear 35 of the turning HST motor 73, respectively. The reversing shafts 43L and 43R respectively rotate the left and right carriers 55L and 55R through differential gears 44L and 44R fixed to one end of the reversing shafts 43L and 43R and carrier gears 56L and 56R, respectively. . In this way, as the turning HST motor 73 rotates, the left and right carriers 55L and 55R of the planetary gear mechanism 50 rotate in the reverse direction. As a result, one planetary gear mechanism 50 is rotated and the other planetary gear mechanism 50 is rotated. Since the gear mechanism 50 is subtracted from the rotation, the left and right drive sprockets 60L and 60R rotate at different rotational speeds to turn the vehicle 1.

  In this way, the HST motor for turning which is driven to rotate by the output of the straight traveling transmitted from the front engine 3 to the rear portion via the main auxiliary transmission 39 in the transmission case 23 and the steering handle 9 is steered. 73 is combined in the differential mechanism (left and right planetary gear mechanisms 50L and 50R) 50, so that the drive sprockets 60L and 60R of the left and right crawler travel devices 80 are differentially rotated to the left or right. In this configuration, the vehicle 1 is turned to the right.

  Further, a plurality of brake plates 29 are formed on one end of the pinion shaft 22 on the pinion shaft 22, and when a brake pedal (not shown) is operated by a driver's operation, the brake arm 28 rotates in conjunction with it. As the brake arm 28 rotates, a brake action is generated on the pinion shaft 22 and the vehicle 1 is decelerated.

  In particular, the brake plate 29 is located at the right end of the pinion shaft 22, and a brake case (not shown) that houses a brake plate, a brake arm, and the like is integrated with a right rear axle case 80R that houses the right planetary gear mechanism 50R. Is possible. Further, since the turning HST motor 73 is located on the left rear axle case 88L, the brake mechanism arranged in the right rear axle case 88R, and the turning HST motor 73 arranged in the left rear axle case 88L Thus, the weight balance of the vehicle 1 can be maintained.

  Furthermore, by arranging the brake mechanism and the turning HST motor 73 separately on the left and right, a link relationship (not shown) constituting the brake mechanism and hydraulic piping (not shown) constituting the turning HST mechanism are provided. It can be arranged separately in the left and right rear axle cases 88L and 88R, which has the effect of improving the maintainability of the vehicle 1.

  Next, the turning mechanism for the turning HST motor output shaft, which is a feature of the present invention, will be described. 6 is a schematic view showing the linkage between the fixing mechanism, the turning HST mechanism and the steering handle, FIG. 7 is a plan view of the turning HST motor, and FIG. 8 is a rear view of the fixing mechanism.

  The turning HST pump 72 and the turning HST motor 73 form a closed circuit connected by two pipes of the pipe 101 and the pipe 102, and in the vicinity of the turning HST pump 72 as the steering handle 9 is steered. A relatively low charge pressure oil (hydraulic oil) sucked from a transmission case strainer (not shown) is introduced into the turning HST pump 72 from a charge pump 72a included in the turning HST pump 72. High pressure hydraulic oil whose supply flow rate (discharge pressure) is adjusted from the turning HST pump 72 to the turning HST motor 73 via the pipes 101 and 102 by the inclination angle of the plate corresponding to the steering degree of the steering handle 9. (Discharge pressure oil) rotates the turning HST motor 73. At this time, when turning right (or turning left), the pipe 101 is on the discharge side, and the pipe 102 is on the suction side. When turning left (or right), the pipe 101 is on the suction side, and the pipe 102 is on the discharge side. become. Note that the movable swash plate (not shown) in the turning HST pump 72 is linked to the steering handle 9 via a rod, a steering arm, a steering shaft, and the like (not shown).

  A member such as a pipe 103 is connected to the charge pressure oil supply portion 72ab of the charge pump 72a, and the other end of the pipe 103 is connected to a fixing mechanism 100 provided on the output shaft 73a of the turning HST motor 73. . Further, the pipe 104 branched from the middle part of the pipe 103 is connected to the other end of the fixing mechanism 100. In order to provide a mounting space for the fixing mechanism 100, the length of the output shaft 73a of the turning HST motor 73 may be appropriately extended.

  An electromagnetic valve 105 is provided in the middle of the pipe 103, and this electromagnetic valve 105 is provided in a steering cam mechanism 113 provided continuously below the steering shaft 112 of the steering handle 9 shown in FIGS. The detector (detection means) 106 using an infrared sensor or the like provided on a stay 114 and the like and provided with a light emitting portion and a light receiving portion for detecting the steering position of the steering handle 9 is interlocked.

  As shown in FIGS. 7 to 8, the fixing mechanism 100 has an outer peripheral portion having a shape such as a cylinder fixed to the rear end of the main body of the turning HST motor 73 so as to cover the output shaft 73 a of the turning HST motor 73. 107 and cylinders 108L and 108R having outer end portions fixed to the outer periphery 107 on the left and right of the output shaft 73a in the rear view, respectively, and the output shaft 73a has cylinders 108L and 108R on the left and right outer periphery. Linings 110L and 110R connected to the pistons 109L and 109R are slidably and detachably provided on the outer periphery of the output shaft 73a.

  And, between the outer ends of the cylinders 108L and 108R in the cylinders 108L and 108R and the outer ends of the pistons 109L and 109R, for example, springs 111L and 111R having both ends fixed are provided as urging means. Further, the ends of the pipe 103 and the pipe 104 are connected to the inside of the cylinders 108L and 108R.

  9 is a side view showing the connection between the steering handle 9 and the turning HST pump 72, FIG. 10 is a perspective view showing the steering cam mechanism 113, and FIG. 11 shows the traveling direction of the vehicle 1 with respect to the steering position of the steering handle 9. It is the shown schematic diagram. Here, when the vehicle 1 travels straight, as shown in FIG. 11, a range including certain play positions b and b ′ for preventing a sudden turn clockwise or counterclockwise around the fixed point position a of the steering handle 9. Since the steering shaft 112 is not rotated by being in the neutral state, the steering arm 114 and the rod 115 are in a stationary state, and a control (not shown) is performed based on information that the detector 106 detects the stationary state of the steering arm 114. Since the solenoid valve 105 is closed by the part or the like, the charge pressure oil from the charge pump 72a is not flowed into the cylinders 108L and 108R.

  Since the pistons 109L and 109R are pushed inward by the biasing of the springs 111L and 111R in the cylinders 108L and 108R, the linings 110L and 110R connected to the pistons 109L and 109R are connected to the turning HST motor 73. As a result of contacting the output shaft 73a so as to cover it, the output shaft 73a is fixed, so that the output shaft 73a is shaken or rotated by a torque reaction force generated in the left and right crawlers in a situation such as an obstacle or unevenness on the road surface when traveling. Therefore, since the differential mechanism 50 is not operated, it is possible to travel straight over a long distance. Accordingly, the straight traveling performance of the vehicle 1 is improved.

  Next, when the vehicle 1 is turning, the fixed position a of the steering handle 9 is rotated clockwise in the direction c beyond the position b, or is rotated left in the direction d beyond the position b ′. Accordingly, the steering input shaft 116 rotates clockwise (or counterclockwise) via the steering shaft 112, and the right turning eccentric cam 117 (or the left turning eccentric cam 118) of the steering cam mechanism 113 rotates right (or Rotate left). The right turning eccentric cam 117 (or the left turning eccentric cam 118) is steered around the steering input shaft 116 via the right turning roller 119 (or the left turning roller 120 and the connecting member 121). The arm 114 is moved forward (or backward), the rod 115 linked to the movable swash plate 72a of the turning HST pump 72 is moved forward (or backward), and the inclination angle of the movable swash plate 72a is changed.

  Therefore, the detector 106 detects that the steering position of the steering handle 9 is the turning position by the movement of the steering arm 114 forward or backward, and the electromagnetic valve 105 is opened based on this information, and the charging is performed. Pressure oil is introduced into the cylinders 108 </ b> L and 108 </ b> R via the pipe 103 and the pipe 104.

  Then, the piston is caused by the pressure of the charge pressure oil larger than the urging force of the springs 111L and 111R flowing into the spaces 108aL and 108aR between the cylinders 108L and 108R inside the cylinders 108L and 108R and the pistons 109L and 109R. Since the linings 110L and 110R are separated from the output shaft 73a when the 109L and 109R are pushed outward against the bias of the springs 111L and 111R, the discharge pressure oil from the turning HST pump 72 flowing in the pipes 101 and 102 As a result, the output shaft 73a rotates and the operation mechanism 50 is operated.

  As described above in detail, the crawler tractor 1 of this example has a crawler frame 81 that rotatably supports a driven idler 85 at both ends, and a drive sprocket 60 mounted on an axle (rear axle) 89, and A crawler type traveling device 80 in which a crawler belt 95 is wound between the driven idler 85 and the drive sprocket 60 is provided at the lower part of the upper vehicle body 90, and the drive sprocket 60 is supplied from the turning HST pump 72 and the turning HST motor 73. A detector that is turned by power, and that the turning HST pump 72 and the turning HST motor 73 are separately arranged, and detects the steering position of the steering handle 9 on the steering arm 114 (steering mechanism) of the steering handle 9. (Detection means) 106, and this detector 106, The output shaft 73a of the T motor 73, in which and a fixing mechanism 100 for fixing the output shaft 73a.

  In addition, an electromagnetic valve 105 that interlocks with the detector 106 is provided in the middle of the pipe (member) 103 for introducing the charge pressure oil of the charge pump 72 a into the fixing mechanism 100, and the fixing mechanism 100 steers the steering handle 9. When the position is a straight traveling position of the vehicle 1 including the play portion and is a neutral position where the turning HST motor 73 does not operate, the output shaft 73a of the turning HST motor 73 is fixedly operated, and the springs 111L and 111R It operates with the (biasing means) and the charge pressure oil of the charge pump 72a. Further, the solenoid valve 105 opens when the steering position of the steering handle 9 is a turning position for turning the vehicle 1.

  The pipe 104 is not limited to being connected to the fixing mechanism 100, and the space 108aL and the space 108aR of the cylinders 108L and 108R are connected by a separate pipe, one space is closed, and one space is connected to the pipe 103. You may connect. Moreover, the outer peripheral part 107 is not restricted to a cylindrical shape, What is necessary is just a shape which can fix the cylinders 108L and 108R. Further, the linings 110L and 110R are not limited to be provided on the left and right sides of the output shaft 73a when viewed from the back, but may be arranged together with the cylinders 108L and 108R above and below the output shaft 73a. It is not limited. Further, the urging means is not limited to the springs 111L and 111R, and a pressure-resistant member that can expand and contract and has elasticity may be used.

  The detector 106 may be attached to the rod 115 without being limited to providing an infrared sensor on the steering arm 114. Further, a limit switch having a make contact and a break contact, a differential transformer for measuring an induced voltage generated by the position of the coil, or the like may be provided on the steering arm 114 or the rod 115. Furthermore, a non-contact angle sensor that detects magnetic flux by rotation of the magnet can be provided on the steering shaft 112.

  In the above-described example, a tractor (agricultural work machine) has been described as an example of a crawler work vehicle. However, the present invention is not limited thereto, and a combiner as a farm work machine, a power shovel as a construction work machine, It can be applied to any work machine equipped with a crawler such as a bull tosa.

It is a side view showing a small crawler type tractor as an example of the present invention. It is a perspective view of the crawler type traveling device vicinity in the tractor shown in FIG. It is a cross-sectional top view in the tractor shown in FIG. It is a cross-sectional side view of the drive part in the tractor shown in FIG. FIG. 2 is an enlarged plan view of the vicinity of a differential mechanism in a mission case in the tractor shown in FIG. 1. It is the schematic which shows linkage with a fixing mechanism, the turning HST mechanism, and a steering handle. It is a top view of a turning HST motor. It is a rear view of a fixing mechanism. It is a side view which shows the connection with a steering handle and the turning HST pump. It is a perspective view which shows a steering cam mechanism. It is the schematic diagram which showed the traveling direction of the vehicle with respect to the steering position of a steering handle. It is a perspective view which shows the conventional small wheel type tractor.

Explanation of symbols

1 Vehicle (crawler tractor)
DESCRIPTION OF SYMBOLS 9 Steering handle 50 Differential mechanism 72 Turning HST pump 72a Charge pump 72ab Charge pressure oil supply part 73 Turning HST motor 73a Output shaft 100 Fixing mechanism 101,102,103,104 Piping 105 Solenoid valve
106 detector 107 outer periphery 108L, 108R cylinder 108aL, 108aR space 109L, 109R piston 110L, 110R lining 111L, 111R spring 112 steering shaft 113 steering cam mechanism 114 steering arm 115 rod a, b, b 'position c, d direction

Claims (5)

A crawler type traveling device having a crawler frame that rotatably supports a driven idler at both ends and a drive sprocket mounted on a rear axle, and a crawler belt wound between the driven idler and the drive sprocket. In the crawler type work vehicle provided at the bottom of the car body,
The drive sprocket is turned by power from a turning HST pump and a turning HST motor, the turning HST pump and the turning HST motor are separately arranged, and a steering mechanism of the steering handle is provided with the steering handle. Detecting means for detecting the steering position;
In conjunction with the detection means, a fixing mechanism for fixing the output shaft to the output shaft of the turning HST motor;
A crawler-type work vehicle comprising:   The crawler work vehicle according to claim 1, further comprising: an electromagnetic valve interlocking with the detection unit in a middle portion of a member that introduces charge pressure oil from a charge pump into the fixing mechanism.   The fixing mechanism includes the output shaft of the turning HST motor when the steering position of the steering handle is a straight running position of the airframe including a play portion and a neutral position where the turning HST motor does not operate. The crawler work vehicle according to claim 1, wherein the crawler work vehicle is fixedly operated.   The crawler work vehicle according to claim 1, wherein the fixing mechanism is operated by an urging unit and charge pressure oil from the charge pump.   2. The crawler work vehicle according to claim 1, wherein the electromagnetic valve opens when a steering position of the steering handle is a turning position for turning the airframe.

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