JP2014193670A - Transmission for travel of service car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid possibility of accidental displacement of a car body due to improper operation with a first operation tool, in a parking state with a parking brake.SOLUTION: There are provided a control unit which, based on operation with a first operation tool, controls action of left and right side clutches 40 for intermittent transmission to left and right travel devices, a parking brake G for braking the left and right travel devices with an intervention of the left and right side clutches 40 for at least one of them, and a linkage state keeping mechanism H which, when the parking brake G is changed to braking state, keeps the left and right side clutches 40 in transmissible connection state such that the left and right travel devices are kept in linkage state regardless of action state of the control unit.

Description

  The present invention includes a left and right traveling device, left and right side clutches that intermittently transmit power to the corresponding traveling device, a control unit that controls the operation of the left and right side clutches, and a steering unit that is linked to the control unit. A first operating tool, a parking brake that brakes the left and right traveling devices via the left and right side clutches for at least one of them, a second operating tool for operating the parking brake, and the second The present invention relates to a traveling transmission device for a work vehicle including a parking brake switching mechanism that switches the parking brake between a braking state and a braking release state based on an operation of an operation tool.

  As a traveling transmission device for a working vehicle as described above, the parking brake is a left and right side clutch (steering clutch) that intermittently transmits power to the left and right traveling devices based on the operation of the first operating tool (steering lever). There is one configured to brake the left and right traveling devices via a mechanism (see, for example, Patent Document 1).

JP 2002-053060 A (paragraph numbers 0024, 0030, 0032, 0040, 0041, FIGS. 1 to 3)

  In the above configuration, when the first operating tool is operated to the left or right first turning position by an erroneous operation or the like in the parking state where the left and right traveling devices are braked by the parking brake, it corresponds to the operation direction of the first operating tool. The braking force from the parking brake to the traveling device is cut off. For this reason, when such an inappropriate operation is performed in a parking state on a sloping ground, the vehicle body may move unexpectedly.

  An object of the present invention is to make it possible to avoid the possibility that the vehicle body may move unexpectedly due to an inappropriate operation of the first operating tool in a parking state by a parking brake.

The problem solving means of the present invention is:
Left and right traveling devices, left and right side clutches that intermittently transmit power to the corresponding traveling device, a control unit that controls the operation of the left and right side clutches, and a first operating tool for steering linked to the control unit A parking brake that brakes the left and right traveling devices via at least one of the left and right side clutches, a second operating tool for parking brake operation, and an operation of the second operating tool A parking brake switching mechanism that switches the parking brake between a braking state and a braking release state based on
When the parking brake is switched to the braking state, the left and right side clutches are maintained in the connected state and the left and right traveling devices are maintained in the interlocked state regardless of the operating state of the control unit. A state maintenance mechanism was provided.

  According to this means, in the parking state in which the parking brake is switched to the braking state, the interlock state maintaining mechanism maintains the left and right side clutches in the connected state in which transmission is possible, regardless of the operation of the first operation tool. The braking force from the parking brake can be transmitted to the left and right traveling devices via the left and right side clutches.

  Therefore, in the parking state by the parking brake, it is possible to avoid the possibility that the vehicle body may move unexpectedly due to inappropriate operation of the first operation tool.

As one of the means for making the present invention more suitable,
Each of the left and right side clutches is configured to be a hydraulic type that switches from the connected state to a disconnected state that cuts off transmission by boosting, and that switches from the disconnected state to the connected state by reducing pressure,
When the first operating tool is operated in the turning direction from the straight traveling position, the control unit is configured to operate the one side corresponding to the operating direction of the first operating tool from a reduced pressure state in which the left and right side clutches are depressurized. It is switched to a pressure increasing state for boosting the clutch, and when the first operating tool is operated toward the straight traveling position, it is configured to be a hydraulic type that switches from the pressure increasing state to the pressure reducing state,
The interlocking state maintaining mechanism is configured by priority decompression means that decompresses the left and right side clutches in preference to the control unit when the parking brake is switched to a braking state.

  According to this means, in the parking state in which the parking brake is switched to the braking state, the right and left side clutches can be transmitted relatively easily by the hydraulic circuit configuration in which the priority pressure reducing means depressurizes the left and right side clutches. The connected state can be maintained, and the braking force from the parking brake can be transmitted to the left and right traveling devices via the left and right side clutches regardless of the operation of the first operation tool.

  Therefore, with a relatively simple hydraulic circuit configuration, it is possible to avoid the possibility that the vehicle body may move unexpectedly due to an inappropriate operation of the first operating tool in the parking state by the parking brake.

As one of the means for making the present invention more suitable,
When the parking brake is switched to a braking state, the priority pressure reducing means cuts off the communication between the operation oil chambers provided in the left and right side clutches and the discharge oil passages, and from the left and right oil chambers. A switching valve that switches from a discharge stop state that stops oil discharge to a discharge state that allows the oil chambers to communicate with the left and right oil chambers and the oil discharge passages to allow oil to be discharged from the left and right oil chambers. did.

  According to this means, the vehicle body is unintentionally displaced due to improper operation of the first operating tool in the parking state by the parking brake by simple improvements such as mounting a switching valve for parking in the hydraulic circuit for the left and right side clutches. The fear of moving can be avoided in advance.

As one of the means for making the present invention more suitable,
The parking brake switching mechanism includes a rotation shaft that switches the parking brake between the braking state and the braking release state by rotating in conjunction with the operation of the second operation tool.
The switching valve is composed of the rotating shaft and a switching oil passage formed on the rotating shaft so as to switch between the discharging stop state and the discharging state as the rotating shaft rotates.

  According to this means, by a simpler improvement using the rotation axis of the parking brake switching mechanism, it is possible to avoid the possibility that the vehicle body may move unexpectedly due to improper operation of the first operation tool in the parking state by the parking brake. can do.

As one of the means for making the present invention more suitable,
With left and right side brakes that brake the left and right traveling devices separately,
The parking brake was constituted by either the left or right side brake.

  According to this means, it is possible to simplify the configuration and reduce the cost by using the side brake also as the parking brake while enabling the brake turning using the side brake.

As one of the means for making the present invention more suitable,
The left and right side clutches and the side brakes corresponding to the left and right side clutches are moved from the brake released state after the side clutch is switched from the connected state to the disconnected state by the operation of the control unit. A unit is formed so that the side clutch is switched from the disengaged state to the connected state after switching to the braking state and after the side brake is switched from the braking state to the braking release state.

  According to this means, the left and right side clutches and the left and right side brakes are separately provided, and the configuration is simplified and the assemblability is improved as compared with the case where the control units are operated individually. Etc.

As one of the means for making the present invention more suitable,
An opening that allows the corresponding side clutch to be assembled from the lateral outer side of the transmission case on the left and right sides of the transmission case incorporating the left and right side clutches and the parking brake, and a cover that closes the opening With members,
A recess is formed in the left and right side portions of the transmission case adjacent to the opening so as to enable fitting of a rotation shaft provided in the parking brake switching mechanism from the lateral outer side of the transmission case. ,
The cover member includes an extraction preventing portion that prevents the rotation shaft from coming out of the recess.

  According to this means, compared with the case where a dedicated member for preventing the rotation shaft from coming out is provided, the configuration can be simplified and the assembling property can be improved by reducing the number of parts.

It is a right view of a normal combine. It is a top view of a normal combine. It is a right view of a transmission case and a hydrostatic continuously variable transmission. It is a front view of a transmission case and a hydrostatic continuously variable transmission. It is a left view of a transmission case and a hydrostatic continuously variable transmission. It is a vertical front view of a transmission case and a hydrostatic continuously variable transmission. It is a vertical front view of the left and right side clutch brake units. FIG. 2 is a hydraulic circuit diagram relating to a hydrostatic continuously variable transmission and left and right side clutch brake units. It is a partially longitudinal right side view showing a retaining structure of a rotating shaft. It is a vertical right side view which shows the structure of the switching valve for priority deceleration. It is a vertical front view of the principal part which shows the structure of a variable relief valve. It is a perspective view of the principal part which shows the support structure of a gasket. It is a left view of the principal part which shows another structure of an oil supply pipe | tube.

  Hereinafter, as an example of a mode for carrying out the present invention, an embodiment in which a traveling transmission device for a work vehicle according to the present invention is applied to a normal combine that is an example of a work vehicle will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the ordinary combine exemplified in the present embodiment cuts an uncut grain culm to be harvested that is located in front of the vehicle body at the left side of the front end of the vehicle body 1 at the time of work traveling. The cutting and conveying device 2 that conveys rearward is connected so as to be movable up and down while extending toward the front of the traveling vehicle body 1. The left half of the traveling vehicle body 1 is equipped with a threshing device 3 that performs a handling process on the harvested cereal meal conveyed by the harvesting and conveying apparatus 2 and performs a sorting process on a processed product obtained by the handling process. A grain tank 5 that stores the grain that has been fed from the bottom of the threshing device 3 via the lifting conveyor 4 is mounted on the rear half of the right half of the traveling vehicle body 1. The grain tank 5 is equipped with a screw conveying type grain discharging device 6 for discharging the grains stored in the grain tank 5 to the outside of the machine. And these are configured to harvest rice, wheat or soybeans.

  In addition, it replaces with the grain tank 5 and the grain discharge | emission apparatus 6 in the traveling vehicle body 1, and equips the bagging apparatus which enables the filling of the grain lifted with the lifting conveyor 4 to the straw bag. Good.

  The traveling vehicle body 1 is provided with a pair of left and right crawlers 8 as left and right traveling devices A at a lower portion of a vehicle body frame 7 formed by connecting a plurality of steel materials such as a square pipe material. A boarding operation unit 9 is formed at a front half of the right half of the body frame 7, and a water-cooled diesel engine (hereinafter referred to as an engine) 11 is provided below a driver seat 10 provided on the rear side of the boarding operation unit 9. Etc. are deployed.

  As the traveling device A, a pair of left and right front wheels and a pair of left and right rear wheels may be employed, or a pair of left and right front wheels and a pair of left and right rear crawlers may be employed.

  The reaping and conveying apparatus 2 has a pair of left and right dividers 12 that separates uncut cereals into harvested and non-harvested cereals as the vehicle travels, at the left and right ends of the front end. doing. A rotary reel 13 is disposed above the front part of the cutting and conveying device 2 so that the tip of the harvested grain culm divided by the left and right dividers 12 is scraped back. A clipper-shaped cutting mechanism 14 that cuts the stock source side of the harvest target cereal is provided at the bottom of the cutting and conveying device 2, and the harvested cereal that has been cut by the cutting mechanism 14 is placed at the rear of the cutting mechanism 14. An auger drum 15 is provided that gathers at a predetermined position in the left-right direction and then feeds back from the predetermined position. And immediately behind the predetermined location, a feeder 16 comprising a slat conveyor is provided for feeding and conveying the harvested cereals fed rearward from the predetermined location toward the cereal input (not shown) of the threshing device 3. doing.

  The cutting and conveying apparatus 2 is a laterally-oriented feeder drive shaft that also serves as an input shaft of the cutting and conveying apparatus 2 provided at the rear end of the feeder 16 by the operation of a hydraulic lifting cylinder 17 installed over the body frame 7 and the feeder 16. It swings up and down using a fulcrum (not shown). The lifting cylinder 17 is actuated by cutting and lifting the cross-swing type neutral return type control lever 18 provided at the front of the boarding operation unit 9 in the front-rear direction to change the operating pressure on the lifting cylinder 17. It can be controlled by switching the operating state of a valve unit (not shown). That is, the cutting and conveying device 2 can be moved up and down by swinging the control lever 18 in the front-rear direction, and cutting height adjustment for changing the height position of the cutting mechanism 14 with respect to the harvested culm is performed. Can do.

  As shown in FIGS. 1 and 3 to 7, the power from the engine 11 is generated by a belt-type transmission 19, a hydrostatic continuously variable transmission (hereinafter referred to as HST) 20, which is an example of a continuously variable transmission B, And, it is transmitted to the left and right crawlers 8 via a traveling transmission system 22 incorporated in the transmission case 21. The HST 20 and the transmission case 21 are arranged at the center of the front of the traveling vehicle body 1 so as to be positioned below the side panel 23 arranged at the left end of the boarding operation unit 9.

  The continuously variable transmission 20 may be a belt-type continuously variable transmission, a hydraulic mechanical continuously variable transmission [HMT], or the like.

  The HST 20 includes a hydraulic pump 25 and a hydraulic motor 26 inside the transmission case 24. The pump shaft of the hydraulic pump 25 also serves as the input shaft 20A of the HST 20, and the motor shaft of the hydraulic motor 26 serves as the output shaft 20B of the HST 20 as well. The transmission case 24 includes a case member 27 in which an accommodation recess 27A that accommodates the hydraulic pump 25 and the hydraulic motor 26 is formed, and a port block 28 that closes the accommodation recess 27A. The hydraulic pump uses an axial plunger type variable displacement pump. An axial plunger type constant variable capacity motor is used as the hydraulic motor.

  An axial plunger type variable displacement motor may be employed as the hydraulic motor.

  As shown in FIGS. 1, 6, and 7, the traveling transmission system 22 is provided with a small-diameter input gear 29 integrally formed with a cylindrical shaft portion 29 </ b> A that is spline-fitted to the output shaft 20 </ b> B of the HST 20. That is, the cylindrical shaft portion 29 </ b> A of the input gear 29 is configured to be the input shaft of the traveling transmission system 22. Then, the power after the shift by the HST 20 taken in by the input gear 29 is used as a reduction unit 30, left and right side clutch brake units 31, left and right output gears 32, and left and right output shafts 33 that rotate integrally with the corresponding output gear 32. , And are transmitted to the left and right crawlers 8.

  The traveling transmission system 22 may have a configuration including a sub-transmission device capable of shifting in multiple stages. Moreover, the structure provided with the right and left reverse transmission unit which enables transmission of reverse rotation power to the corresponding crawler 8 on either side may be sufficient.

  The reduction unit 30 includes a large-diameter first reduction gear 34 that meshes with the input gear 29, a small-diameter second reduction gear 36 that is spline-fitted to the first relay shaft 35 together with the first reduction gear 34, and a second reduction gear. 36, a large-diameter third reduction gear 37 that meshes with 36, and the like. The third reduction gear 37 is spline-fitted to the second relay shaft 39 in a state in which the third reduction gear 37 is fixed to be non-slidable by a stopper 38.

  The left and right side clutch brake units 31 are composed of a meshing type side clutch 40 and a multi-plate type side brake 41. The left and right side clutches 40 are cylindrically movable pawl shafts 42 fitted on the center side of the second relay shaft 39 so as to be relatively rotatable and relatively slidable, and are not slidable on the end side of the second relay shaft 39. A ring-shaped fixed claw shaft 43 that is spline-fitted in a state, a compression spring 44 that slidably urges the movable claw shaft 42 in a direction to engage with the fixed claw shaft 43, and the like. The movable claw shaft 42 is slidably displaced over a meshing position where it engages with the fixed claw shaft 43 and a release position where the meshing with the fixed claw shaft 43 is released. The left and right side brakes 41 include a plurality of brake discs 45 that are spline-fitted to the movable claw shaft 42, a plurality of separator plates 46 that are alternately fitted to the movable claw shaft 42 alternately with the brake disc 45, and a pressure plate 47. It is composed. A collar 48 that allows a series of sliding operations of the movable claw shaft 42 and the pressure plate 47 is fitted on the outer end portion of each movable claw shaft 42.

  The left and right side clutch brake units 31 are provided with cylindrical pistons 49 that enable hydraulic operation of the movable claw shaft 42 and the pressure plate 47 via the collar 48. The left and right pistons 49 are slidably displaced from the meshing position to the release position by sliding the movable pawl shaft 42 in the direction against the action of the compression spring 44 as the pressure is increased, thereby causing the corresponding side clutch 40 to move. The transmission state is switched from a transmission state to a cutoff state where transmission is cut off, and then the pressure plate 47 is slid in the direction against the action of the compression spring 44 together with the movable claw shaft 42 to press each separator plate 46 and the pressure plate 47. By doing so, the corresponding side brake 41 is configured to be switched from the braking release state to the braking state. In addition, by allowing the movable claw shaft 42 to be slid by the action of the compression spring 44 as the pressure is reduced, the pressure plate 47 releases the pressure on each separator plate 46 and the pressure plate 47 and the corresponding side brake. 41 is switched from the braking state to the braking release state, and then the movable claw shaft 42 is slid and displaced from the release position to the meshing position, and the corresponding side clutch 40 is switched from the disconnected state to the transmission state.

  That is, in the left and right side clutch brake units 31, the side brake 41 is switched from the brake release state to the brake state after the side clutch 40 is switched from the transmission state to the cutoff state by the pressure increase, and the side brake 41 is released from the brake state by the pressure reduction. The hydraulic clutch is configured such that the side clutch 40 is switched from the disconnected state to the transmission state after switching to the braking release state.

  Note that the left and right side clutch brake units 31 may be configured to be, for example, an electric type that switches the operating states of the side clutch 40 and the side brake 41 as described above by operating an electric cylinder.

  The left and right output gears 32 mesh with the movable claw shafts 42 of the corresponding side clutch brake units 31. The power or braking force is transmitted to the left and right crawlers 8 via the corresponding output shafts 33.

  As shown in FIGS. 3 to 7 and FIG. 9, the transmission case 21 has a left and right divided structure that can be divided into left and right from the left first case member 51 and the right second case member 52. And in the state which joined the outer peripheral part of the 1st case member 51, and the outer peripheral part of the 2nd case member 52, the input gear 29 of the driving | running | working transmission system 22 is accommodated by bolting several places of those outer peripheral parts. And a second case portion 21B that accommodates the speed reduction unit 30 of the traveling transmission system 22, the left and right output gears 32, and the like. Further, the third case member 53 is bolted to the outer surface of the first case member 51 to form a third case portion 21C that accommodates the left side clutch brake unit 31 and the like. A fourth case member 21D that accommodates the right side clutch brake unit 31 and the like is formed by bolting the fourth case member 54 to the side surface. The third case member 53 and the fourth case member 54 have openings 53A that allow assembly of the corresponding side clutch brake units 31 from the left and right lateral outer sides with respect to the third case portion 21C and the fourth case portion 21D, 54A is formed, and the left and right cover member 55 that closes the openings 53A and 54A is bolted. The left and right cover members 55 support the end of the second relay shaft 39 and the piston 49, and form a piston operating oil chamber 21E between the corresponding third case member 53 and the fourth case member 54. ing. A left and right output shaft case 56 that surrounds the output shaft 33 extending from the transmission case 21 to the left and right is connected to the lower portion of the first case member 51 and the second case member 52 by bolts.

  As shown in FIGS. 3 to 6, the first case portion 21 </ b> A of the transmission case 21 has a left first outer wall portion 21 a that supports the input gear 29 and a right second outer wall portion 21 b adjacent to the input gear 29. It is narrow. An opening that allows spline fitting between the cylindrical shaft portion 29A of the input gear 29 and the output shaft 20B of the HST 20 is formed in the central portion of the first outer wall portion 21a. A connection surface 21c that enables the connection of the HST 20 is formed in a portion around the input gear 29 located around the input gear 29 on the outer surface of the first outer wall portion 21a. Four through holes 21d that allow the HST 20 to be connected to the connecting surface 21c are formed in the input gear peripheral portion located around the input gear 29 in the first outer wall portion 21a and the second outer wall portion 21b. The case member 27 of the HST 20 has a joint surface 27a that is joined to the connection surface 21c of the first outer wall portion 21a at the output shaft peripheral portion located around the output shaft in the right outer wall portion located on the opposite side of the port block 28. , Four screw holes 27b corresponding to the respective through holes 21d of the first case portion 21A are formed. The connecting surface 21c of the first case portion 21A is provided with a positioning pin 57 for the case member 27 of the HST 20, and a positioning hole 27c for the first case portion 21A of the transmission case 21 is formed in the joint surface 27a of the case member 27. ing.

  When the HST 20 is coupled to the transmission case 21 from the above configuration, first, the coupling surface 21c formed on the first outer wall portion 21a of the transmission case 21 and the joint surface 27a formed on the case member 27 of the HST 20 are opposed to each other. In this state, the output shaft 20B of the HST 20 is spline-fitted to the cylindrical shaft portion 29A of the input gear 29, and the positioning pin 57 of the connecting surface 21c is engaged with the positioning hole 27c of the joining surface 27a. Thereby, HST20 can be positioned with respect to the transmission case 21 in the state in which each through-hole 21d of the transmission case 21 and each screw hole 27b of HST20 oppose appropriately. After this positioning, four bolts 58 as screwing members for the respective screw holes 27b are inserted into the corresponding through holes 21d from the right outer side of the transmission case 21 and screwed into the corresponding screw holes 27b. The HST 20 can be easily connected to the case 21 from the right outer side of the transmission case 21 in a state where the joint surface 27a of the case member 27 is appropriately joined to the connection surface 21c of the first outer wall portion 21a. Further, by this screwing, the connection of the first case member 51 and the second case member 52 in the transmission case 21 at the first case portion 21A can be further strengthened. And in this connection state, since the port block 28 which is easy to heat up with a high pressure is located in the outer side away from the transmission case 21, the heat radiation from the port block 28 can be promoted, and the rise in the oil temperature is suppressed. be able to.

  That is, the output shaft 20B of the HST 20 and the input gear 29 of the transmission case 21 can be interlocked by the four screw holes 27b formed in the case member 27 of the HST 20 and the four bolts 58 screwed into these. The connecting means C for appropriately connecting the transmission case 21 and the HST 20 is configured.

  Note that the transmission case 21 is formed with a connecting surface 21c at the peripheral portion of the input gear 29 located around the input gear 29 on the outer surface of the second outer wall portion 21b, so that the HST 20 is connected to the second outer wall from the left outer side of the transmission case 21. You may comprise so that it may connect in the state which joined the joint surface 27a of the case member 27 to the connection surface 21c of the part 21b. The HST 20 may be configured to be connected to the transmission case 21 in a state where the joint surface 27 a is formed on the port block 28 and the port block 28 is joined to the transmission case 21. The transmission case 24 of the HST 20 is provided with stud bolts as four screwing portions 27b, and the connecting means C is constituted by these stud bolts and four nuts as screwing members 58 screwed into the stud bolts. May be. The number of screwing portions 27b and screwing members 58 may be two, three, or five or more. A positioning hole may be formed in the connecting surface 21c of the transmission case 21 and a positioning pin 57 may be provided on the joint surface 27a of the HST 20.

  The input shaft 20 </ b> A of the HST 20 is located at a position deviating upward from a position facing the transmission case 21 in a state where the HST 20 is coupled to the transmission case 21. The protruding portion of the input shaft 20A that protrudes rightward from the case member 27 of the transmission case 24 has a length such that the protruding end portion is located on the right outer side of the second outer wall portion 21b of the transmission case 21, and The output pulley of the belt type transmission 19 is provided as an input pulley 59 at the protruding end portion. The case member 27 includes a shaft support portion 27B that extends to the vicinity of the protruding end portion of the input shaft 20A and supports the protruding end side of the input shaft 20A. The shaft support portion 27 </ b> B is provided with a plurality of heat sinks 27 </ b> C using a space between the HST 20 and the input pulley 59, thereby improving the cooling efficiency of the HST 20. The input pulley 59 can be attached from the right outer side of the transmission case 21 to the protruding end portion of the input shaft 20A. When the input pulley 59 is attached to the protruding end portion of the input shaft 20A, four bolts 58 are attached in the assembly direction. It overlaps with the upper two of them.

  That is, the connection between the HST 20 and the transmission case 21 is performed using the space between the HST 20 and the input pulley 59, so that the left and right sides of the traveling transmission system 22 can be moved from the input shaft 20 A of the HST 20. The speed change transmission system over the output shaft 33 can be configured compactly.

  As shown in FIGS. 1 to 8, the left and right side clutch brake units 31 are linked to the control lever 18 via a control unit D and the like. The control unit D changes the relief pressure for the left and right side clutch brake units 31 based on the switching valve 60 that switches the oil flow to the left and right side clutch brake units 31 based on the operation of the control lever 18 and the operation of the control lever 18. The valve unit 63 includes a variable relief valve 61 and a relief valve 62 that opens when the internal pressure of the left and right side clutch brake units 31 exceeds a set value.

  Note that the control unit D may adopt an electrohydraulic control type using an electromagnetic valve. In addition, when the left and right side clutch brake units 31 are configured electrically, an electronic control type is adopted.

  When the control lever 18 is positioned in the straight traveling position, the control unit D maintains the pressure-reducing state in which the left and right side clutch brake units 31 are depressurized, maintains the left and right side clutches 40 in the transmission state, and The side brake 41 is maintained in a brake release state. As a result, it is possible to obtain a straight traveling state in which the left and right crawlers 8 are driven at a constant speed and the vehicle body travels straight. When the control lever 18 is operated to the left from the straight position, the left side clutch 40 is moved from the reduced pressure state to the left pressure increasing state in which the left side clutch brake unit 31 acting on the left crawler 8 is increased. After switching from the transmission state to the cutoff state, the left side brake 41 is switched from the braking release state to the braking state with an operation amount corresponding to the operation amount to the left of the control lever 18. Thereby, it is possible to switch from the straight traveling state to the left turning state in which the left crawler 8 is driven or braked to turn the vehicle body leftward. When the control lever 18 is operated rightward from the straight traveling position, the right side clutch 40 is moved from the reduced pressure state to the right pressure increasing state in which the right side clutch brake unit 31 acting on the right crawler 8 is increased. After switching from the transmission state to the cutoff state, the right side brake 41 is switched from the braking release state to the braking state with an operation amount corresponding to the operation amount to the right of the control lever 18. Thereby, it is possible to switch from the straight traveling state to the right turning state in which the right crawler 8 is driven or braked to turn the vehicle body in the right direction. When the control lever 18 is operated from one of the left and right operation positions toward the straight traveling position, the side brake 41 in the braking state is switched to the braking release state by switching from the left pressure increasing state or the right pressure increasing state to the pressure decreasing state. Thereafter, the side clutch 40 in the disconnected state is switched to the transmission state. Thereby, it can switch from a left turn state or a right turn state to a straight drive state.

  That is, the control lever 18 is configured to function as the first operation tool E for steering. In addition, as the first operating tool E, a steering wheel that rotates in the turning direction may be employed.

  As shown in FIGS. 1-4 and FIGS. 6-8, the parking brake pedal 64 is arrange | positioned as the 2nd operation tool F for parking brake operation in the step part of the boarding operation part 9. As shown in FIG. The parking brake pedal 64 is returned to the depression release position by urging a return spring (not shown), and can be held at the depression position by the depression operation to the depression position against the action of the return spring. The position holding at the depressed position can be released by the depression operation in the holding state. The right side brake 41 switches from the braking release state to the braking state in conjunction with the depression operation to the depression position, and the right side brake 41 brakes from the braking state in conjunction with the return to the depression release position. The vehicle is linked to the right side brake 41 via the parking brake switching mechanism 65 and the like so as to switch to the released state. That is, the right side brake 41 is configured to function as the parking brake G.

  The left side brake 41 may function as the parking brake G. Further, a dedicated parking brake G that brakes the left and right crawlers 8 via the left and right side clutch brake units 31 may be provided.

  The parking brake switching mechanism 65 has a ring-shaped operation member 66 fitted on the collar 48 so as to act on the pressure plate 47, and a rotation shaft that engages with the operation member 66 in a state in which the operation member 66 can be rotated. 67, the operation arm 68 connected to the right end of the rotation shaft 67, and the fourth case member 54 and the operation member 66 so as to slide and displace the operation member 66 in the left-right direction as the operation member 66 rotates. And a climbing cam mechanism 69 formed between the two. The operation arm 68 is linked to the parking brake pedal 64 via a mechanical linkage mechanism (not shown). As a result, the rotation shaft 67 rotates forward in conjunction with the depression operation of the parking brake pedal 64 to the depression position, and the operation member 66 rotates forward and slides in the left direction in conjunction with the forward rotation. Thus, the pressure plate 47 is pressed to switch the right side brake 41 from the braking release state to the braking state. The rotary shaft 67 reverses in conjunction with the return of the parking brake pedal 64 to the depressing release position, and the operating member 66 reverses in conjunction with the reverse rotation and slides in the right direction. 47 is released, and the right side brake 41 is configured to switch from the braking state to the braking release state.

  As a result, the parking brake pedal 64 is held in the depressed position while the control lever 18 is positioned in the straight traveling position, so that the braking force by the right side brake 41 is applied to the left and right side clutch brake units 31 via the left and right side clutch brake units 31. It can be made to act on the crawler 8, and it can switch to the parking state which maintains the state which stopped the vehicle body by braking.

  In addition, as the second operation tool F, an operation lever or a switch configured to be able to switch and hold between the parking position and the parking release position may be employed. The parking brake switching mechanism 65 is an electric type that switches the right side brake 41 from the braking release state to the braking state by cutting off the energization, or a hydraulic type that switches the right side brake 41 from the braking release state to the braking state by pressure reduction. You may comprise.

  As shown in FIGS. 3 to 9, the transmission case 21 is connected to the opening 54 </ b> A for assembling the side clutch brake unit on the right side of the transmission case 21. A recess 21 </ b> F that enables the fitting of the moving shaft 67 is formed. The left and right cover members 55 are integrally formed with an extraction preventing portion 55A that prevents the rotation shaft 67 from coming out of the recess 21F via a C-shaped ring 70 that is engaged with the right end of the rotation shaft 67. doing.

  As shown in FIGS. 6 to 8 and FIG. 10, the transmission case 21 operates the control unit D when the right side brake 41 (parking brake G) is switched to the braking state by depressing the parking brake pedal 64. Regardless of the state, an interlocked state maintaining mechanism H is provided that maintains the side clutch 40 of the left and right side clutch brake units 31 in the connected state and maintains the left and right crawlers 8 in the interlocked state.

  When the right side brake 41 is switched to the braking state by the depressing operation of the parking brake pedal 64, the interlocking state maintaining mechanism H and the oil chamber 21E for operating the piston provided in the left and right side clutch brake units 31 and the discharge oil passage In this state, the left and right oil chambers 21E are communicated with the discharge oil passage 72 from the stoppage state (see FIG. 10A) in which the communication with the 72 is cut off and the oil discharge from the left and right oil chambers 21E is stopped. Priority is given to decompressing the left and right side clutch brake units 31 in preference to the control unit D by switching to a discharge state (see FIG. 10B) that allows oil to be discharged from the left and right oil chambers 21E. The switching valve 71 is used as the pressure reducing means Ha. The switching valve 71 includes a rotating shaft 67 and a switching oil passage 73 formed on the rotating shaft.

  In the parking state in which the parking brake pedal 64 is held in the depressed position and the braking force from the right side brake 41 is applied to the left and right crawlers 8 via the left and right side clutch brake units 31 from the above configuration. Even when the control lever 18 is operated to the left or right from the straight traveling position by the above, it is possible to prevent the pressure increase of the left or right side clutch brake unit 31 based on the operation of the control lever 18. As a result, in a parking state on an inclined ground, due to an erroneous operation of the control lever 18, either the left or right side clutch brake unit 31 is boosted, and either the left or right side clutch 40 is switched from the connected state to the disconnected state. Further, it is possible to avoid the possibility that the braking force by the right side brake 41 does not act on the left crawler 8 and the vehicle body turns, for example.

  The interlocking state maintaining mechanism H may employ a configuration that prevents the operation of the control lever 18 from the straight position in the left-right direction in the parking state. The priority pressure reducing means Ha may be configured by a dedicated switching valve that is separate from the rotating shaft 67. Further, an electromagnetic valve may be adopted as the switching valve 60 of the control unit D so that the switching valve 60 is maintained in a reduced pressure state in preference to the operation of the control lever 18.

  As shown in FIGS. 3 to 6 and 8, the port block 28 of the HST 20 is connected with a first hydraulic pump 74 for charging and a second hydraulic pump 75 for steering driven by the input shaft 20 </ b> A of the HST 20. Yes. The first hydraulic pump 74 sucks lubricating oil stored in the transmission case 21 through the suction oil passage 76 and the oil filter 77 and supplies the oil to the HST 20 through the charge oil passage 78 and the like. The second hydraulic pump 75 sucks the lubricating oil stored in the transmission case 21 through the suction oil passage 76 and the oil filter 77 and supplies the oil to the valve unit 63 through the oil supply passage 79 and the like. The valve unit 63 supplies oil from the second hydraulic pump 75 to the oil chambers 21E of the left and right side clutch brake units 31 via the switching valve 60, the left and right supply / discharge oil passages 80 and 81, and the like. Further, the oil in the oil chambers of the left and right side clutch brake units 31 is changed to the switching valve 60 and the left and right supply / discharge oil passages 80 and 81 and the discharge oil passage 72, or the relief oil passage 82 and the variable relief valve 61 or the relief valve 62. Alternatively, the oil is discharged into the transmission case 21 through the switching oil passage 73 and the discharge oil passage 72.

  The suction oil passage 76 has an external oil passage portion formed by a steel pipe suction hydraulic pipe 83 extending from the lower part of the transmission case 21 to the upper part of the transmission case 24. The oil supply passage 79 has an external oil passage portion formed by a steel pipe supply hydraulic pipe 84 extending from the second hydraulic pump 75 to the valve unit 63. The left oil supply / discharge oil passage 80 has an external oil passage portion formed by a first hydraulic pipe 85 made of a steel pipe extending between the left side of the transmission case 21 and the valve unit 63. The right oil supply / discharge oil passage 81 has an external oil passage portion formed by a second hydraulic pipe 86 made of steel pipe extending between the right side of the transmission case 21 and the valve unit 63.

  As described above, when connecting the HST 20 to the transmission case 21, the spline fitting between the output shaft 20B of the HST 20 and the cylindrical shaft portion 29A of the input gear 29 on the transmission case side, and the positioning hole 27c of the HST 20 and the transmission are performed. By the engagement of the case 21 with the positioning pin 57, the HST 20 can be properly positioned with respect to the transmission case 21. This prevents variations in the distance between the connecting portion 21H to the suction hydraulic pipe 83 provided at the lower portion of the transmission case 21 and the connecting portion 20C to the suction hydraulic pipe 83 provided at the upper portion of the HST 20. Thus, the connection between the transmission case 21 and the HST 20 by the suction hydraulic pipe 83 can be facilitated.

  As shown in FIGS. 3 to 6, the transmission case 21 is formed such that the lower side that houses the left and right output gears 32 is a bulging portion 21 </ b> G that bulges forward from the upper side. The valve unit 63 is bolted to the front right side portion of the transmission case 21 on the upper side of the bulging portion 21G so as not to protrude forward from the front end of the bulging portion 21G. The valve case 87 of the valve unit 63 has a supply connecting portion 87A that enables connection of the supply hydraulic tube 84 and a first connection portion 87B that enables connection of the first hydraulic tube 85 on the left side surface. I have. Further, a second connection portion 87C that enables connection of the second hydraulic pipe 86 is provided on the upper surface. An elbow 88 that connects the supply hydraulic pipe 84 and the first hydraulic pipe 85 to the supply connection section 87A and the first connection section 87B from above is connected to the supply connection section 87A and the first connection section 87B.

  The second hydraulic pump 75 has a supply connection portion 75 </ b> A that enables connection of the supply hydraulic pipe 84 formed on the front surface thereof. The transmission case 21 includes a first connection portion 53B that enables connection of the first hydraulic pipe 85 to the front surface of the third case member 53, and a connection of the second hydraulic pipe 86 to the front surface of the fourth case member 54. A second connection portion 54B is provided that enables this. An elbow 88 that enables connection of the first hydraulic pipe 85 and the second hydraulic pipe 86 from above is connected to the first connecting portion 53B and the second connecting portion 54B.

  The supply hydraulic pipe 84 is behind the front end of the bulging portion 21G in the transmission case 21 in a state where the supply connection portion 75A of the second hydraulic pump 75 and the supply connection portion 87A of the valve case 87 are connected. In a positioned state, it is bent so as to fit within the left and right width of the HST 20 and within the left and right width of the transmission case 21. The first hydraulic pipe 85 is bent and formed in a substantially U shape that is upside down. The second hydraulic pipe 86 is bent and formed in a substantially J shape that is upside down.

  From the above configuration, the connection of the first hydraulic pipe 85 to the first connection portion 53B of the transmission case 21 and the first connection portion 87B of the valve case 87 can be easily performed by a connection operation from above. The first hydraulic pipe 85 is positioned behind the front end of the bulging portion 21G in the transmission case 21 in a state where it is connected to the first connection portion 53B of the transmission case 21 and the first connection portion 87B of the valve case 87. In such a state, the HST 20 fits within the left-right width and the transmission case 21 fits within the left-right width. Further, the second hydraulic pipe 86 can be easily connected to the second connecting portion 54B of the transmission case 21 and the second connecting portion 87C of the valve case 87 by a connecting operation from above. The second hydraulic pipe 86 is positioned behind the front end of the bulging portion 21G in the transmission case 21 in a state where the second hydraulic pipe 86 is connected to the second connection portion 54B of the transmission case 21 and the second connection portion 87C of the valve case 87. In such a state, it fits within the lateral width of the transmission case 21.

  The valve case 87 has a supply connection portion 87A, a first connection portion 87B, and a second connection portion 87C connected to one or several of the left side surface, the right side surface, the top surface, and the bottom surface. Alternatively, a distributed connection may be configured. The valve case 87 has a shape having a projecting portion projecting laterally outward from the lateral side portion thereof, and the lateral side portion of the valve case 87 is configured to include a connecting portion for piping on the upper surface of the projecting portion. However, the hydraulic pipe may be connected to the connecting portion from above. The valve unit 63 may be bolted to the front left side of the transmission case 21 on the upper side of the bulging portion 21G so as not to protrude forward from the front end of the bulging portion 21G.

  As shown in FIGS. 3 to 5, the transmission case 21 includes an oil supply pipe 89 that allows oil to be supplied to the inside of the transmission case 21. The oil supply pipe 89 is inclined so as to be separated from the HST 20 and the input pulley 59 to the right front side, and the upper end of the oil supply port 89A and the breather 90A provided in the cap 90 for opening and closing the oil supply port 89A are located above the upper end of the HST 20 It extends upward to be located at

  Thereby, the oil supply from the oil supply port 89A of the oil supply pipe 89 to the inside of the transmission case 21 can be easily performed from the front upper side of the oil supply port 89A without being hindered by the HST 20 and the input pulley 59. Moreover, the oil blow-up from the transmission case 21 can be more effectively suppressed, and the intrusion of muddy water from the breather 90A or the like in a field with much water can be effectively suppressed.

  Note that the oil supply pipe 89 may extend directly above such that the upper oil supply port 89A is located above the upper end of the HST 20. Moreover, you may extend upward in the inclination attitude | position which leaves | separates from HST20 and the input pulley 59 to the front side. Furthermore, as shown in FIG. 13, the side panel 23 provided in the boarding operation unit 9 is located on the left outer side, and the upper filler port 89 </ b> A extends upward so as to be located near the upper end of the side panel 23. May be.

  As shown in FIG. 11, in the valve unit 63, the operation shaft 91 rotates in conjunction with the swinging operation of the control lever 18 in the left-right direction, so that the cam 92 provided on the operation shaft 91 The 60 spools 93 and the spool 94 of the variable relief valve 61 are configured to slide. The spool 94 of the variable relief valve 61 is pressed by the cam 92 with the passive member 95 provided at one end of the spool 94 as the operation amount in the left-right direction from the straight advance position of the control lever 18 increases. The relief pressure for the left and right side clutch brake units 31 is increased by a large displacement in the direction against the above action. And when the passive member 95 contact | abuts to the valve seat part 87D formed in the valve case 87, it is comprised so that the relief pressure with respect to the left and right side clutch brake units 31 may become the maximum.

  From this configuration, by operating the control lever 18 and adjusting the pressure so that a predetermined maximum pressure is obtained in a state where the passive member 95 is in contact with the valve seat portion 87D, for example, both the left and right sides of the control lever 18 are adjusted. As compared with the case of adjusting the pressure so that the same pressure can be obtained at the same operating angle while measuring the operating angle of the angle, the labor required for adjusting the pressure is greatly reduced, and the operating direction of the control lever 18 is changed. In addition, it is possible to effectively suppress the occurrence of variation in the relationship between the operation amount from the straight position of the control lever 18 and the relief pressure with respect to the side clutch brake unit 31. This variation can be more effectively suppressed by increasing the processing accuracy of the contact surface between the passive member 95 and the valve seat portion 87D.

  As shown in FIG. 12, two stud bolts 97 are provided at the mounting position of the valve unit 63 in the transmission case 21. Thus, when the valve unit 63 is bolted to the transmission case 21, the gasket 98 interposed between the transmission case 21 and the valve case 87 of the valve unit 63 can be supported by the two stud bolts 97. It is possible to prevent the gasket 98 from falling off or being displaced. As a result, the valve unit 63 can be easily attached to the transmission case 21 via the gasket 98.

In the traveling transmission device for a work vehicle according to the present invention, the parking brake brakes the left and right traveling devices via the left and right side clutches that intermittently transmit power to the left and right traveling devices based on the operation of the first operation tool. For example, the present invention can be applied to an ordinary combiner, a self-removing combiner, a carrot harvester, a corn harvester, a transporter, a tractor, and the like.
Etc.

21 Transmission Case 21E Oil Chamber 21F Concave 40 Side Clutch 41 Side Brake 53A Opening 54A Opening 55 Cover Member 55A Extraction Prevention Part 65 Parking Brake Switching Mechanism 67 Rotating Shaft 71 Switching Valve 72 Discharged Oil Path 73 Switching Oil Path A Traveling Device D Control unit E 1st operation tool F 2nd operation tool G Parking brake H Interlocking state maintenance mechanism Ha Preferential decompression means

Claims (7)

Left and right traveling devices, left and right side clutches that intermittently transmit power to the corresponding traveling device, a control unit that controls the operation of the left and right side clutches, and a first operating tool for steering linked to the control unit A parking brake that brakes the left and right traveling devices via at least one of the left and right side clutches, a second operating tool for parking brake operation, and an operation of the second operating tool A parking brake switching mechanism that switches the parking brake between a braking state and a braking release state based on
When the parking brake is switched to the braking state, the left and right side clutches are maintained in the connected state and the left and right traveling devices are maintained in the interlocked state regardless of the operating state of the control unit. A work vehicle traveling transmission device including a state maintaining mechanism. Each of the left and right side clutches is configured to be a hydraulic type that switches from the connected state to a disconnected state that cuts off transmission by boosting, and that switches from the disconnected state to the connected state by reducing pressure,
When the first operating tool is operated in the turning direction from the straight traveling position, the control unit is configured to operate the one side corresponding to the operating direction of the first operating tool from a reduced pressure state in which the left and right side clutches are depressurized. It is switched to a pressure increasing state for boosting the clutch, and when the first operating tool is operated toward the straight traveling position, it is configured to be a hydraulic type that switches from the pressure increasing state to the pressure reducing state,
2. The work vehicle according to claim 1, wherein the interlocking state maintaining mechanism is configured by priority decompression means that decompresses the left and right side clutches in preference to the control unit when the parking brake is switched to a braking state. Traveling transmission device.   When the parking brake is switched to a braking state, the priority pressure reducing means cuts off the communication between the operation oil chambers provided in the left and right side clutches and the discharge oil passages, and from the left and right oil chambers. A switching valve that switches from a discharge stop state that stops oil discharge to a discharge state that allows the oil chambers to communicate with the left and right oil chambers and the oil discharge passages to allow oil to be discharged from the left and right oil chambers. The transmission device for traveling a work vehicle according to claim 2. The parking brake switching mechanism includes a rotation shaft that switches the parking brake between the braking state and the braking release state by rotating in conjunction with the operation of the second operation tool.
The said switching valve is comprised from the said rotating shaft and the switching oil path formed in the said rotating shaft so that it may switch to the said discharge stop state and the said discharge state with rotation of the said rotating shaft. 4. A work vehicle traveling transmission device according to 3. With left and right side brakes that brake the left and right traveling devices separately,
The transmission device for traveling a work vehicle according to any one of claims 1 to 4, wherein the parking brake is configured by one of the left and right side brakes.   The left and right side clutches and the side brakes corresponding to the left and right side clutches are moved from the brake released state after the side clutch is switched from the connected state to the disconnected state by the operation of the control unit. 6. The work vehicle according to claim 5, wherein the vehicle is unitized so that the side clutch is switched from the disengaged state to the connected state after the side brake is switched from the braking state to the braking release state. Traveling transmission device. An opening that allows the corresponding side clutch to be assembled from the lateral outer side of the transmission case on the left and right sides of the transmission case incorporating the left and right side clutches and the parking brake, and a cover that closes the opening With members,
A recess is formed in the left and right side portions of the transmission case adjacent to the opening so as to enable fitting of a rotation shaft provided in the parking brake switching mechanism from the lateral outer side of the transmission case. ,
The transmission device for traveling a work vehicle according to any one of claims 1 to 6, wherein the cover member includes an extraction preventing portion that prevents the rotation shaft from coming out of the recess.

Images