JP2005330977A - Tractor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent contamination inside a transmission case with external foreign materials such as water when air flows into the transmission case from a breather, by eliminating the breather provided in a transmission to adjust internal pressure of the transmission case. <P>SOLUTION: The tractor is provided with am extraction pipe 80 over the transmission case 30, and inside the transmission case 31 and a sealed space structured in a step 13 are communicated with each other through the extraction pipe 80 and a hose 81. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tractor provided with a member for adjusting the internal pressure of a transmission case in a transmission.

  2. Description of the Related Art Conventionally, in a tractor, a transmission is disposed at the rear part of the machine body, and a hydraulic lift device for raising and lowering a work machine disposed at the rear part of the machine body is disposed above the transmission. The hydraulic lift device includes a hydraulic case that houses a hydraulic cylinder, and left and right lift arms that protrude from the hydraulic case, and the hydraulic case communicates with a transmission transmission case. Further, an inverted “U” -shaped breather for adjusting the internal pressure of the transmission case is provided on the upper portion of the hydraulic case (see, for example, Patent Document 1).

Japanese Utility Model Publication No. 56-76119

  In the conventional technology, a sponge is fitted into the external opening of the breather to prevent water from entering the mission case from the outside. However, when using a large amount of water for the tractor, such as when washing a car, It was not possible to reliably prevent water contamination. Further, since external air is taken into the mission case, the sponge is likely to deteriorate due to dust and the like, and maintenance such as periodic replacement of the sponge has been necessary.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in the first aspect, an extraction pipe is provided above the transmission case, and the inside of the transmission case and the sealed space provided on the airframe are communicated with each other via the extraction pipe and the hose.

  According to a second aspect of the present invention, the sealed space is configured as a step.

  As effects of the present invention, the following effects can be obtained.

  In the first aspect of the present invention, an extraction pipe is provided above the transmission case, and the inside of the transmission case and the sealed space provided on the fuselage are communicated with each other via the extraction pipe and the hose. Even if it changes, the air in the sealed space can be adjusted by expanding or compressing, and the breather can be eliminated. It is possible to reliably prevent foreign matters such as water from entering the mission case from the outside.

  According to the second aspect of the present invention, since the sealed space is configured as a step, it is not necessary to arrange the sealed space in the other part of the machine body, and the existing apparatus is not obstructed. Further, the step can be easily and integrally formed by blow molding, and the step can be easily manufactured at low cost.

Next, embodiments of the invention will be described.
1 is a side view showing an overall configuration of a tractor according to an embodiment of the present invention, FIG. 2 is a side sectional view of a transmission, FIG. 3 is a side sectional view of a step, and FIG. FIG. 5 is a side view of the suction strainer, and FIG. 6 is a perspective view of the suction strainer.

First, an overall configuration of an embodiment in which the present invention is applied to the tractor 1 will be described.
As shown in FIG. 1, in the tractor 1, airframe frames 2, 2 are arranged in parallel in the left-right direction in the front-rear direction, and the engine 3 is placed in front of the airframe frames 2, 2. A battery 4 and a radiator 5 are disposed in front of the engine 3, a muffler 6 is disposed above the engine 3, and these devices are covered with a hood 7 together with the engine 3. A fuel tank 8 is disposed in the rear part of the bonnet 7, and a dashboard 9 is disposed behind the fuel tank 8. A handle column 10 is disposed in the dashboard 9, and a handle 11 is provided at the upper end of the handle shaft supported by the handle column 10. A seat 12 is disposed behind the handle 11 disposed on the dashboard 9, and steps 13 and 13 are supported by the body frame 2 and 2 on the left and right front and lower sides of the seat 12, respectively. ing. In addition, a protective frame 14 is provided at the rear of the aircraft to protect the driver when the vehicle falls over.

  A transmission 15 is provided at the rear part of the body frame 2. 2, and rear axle cases 16 and 16 are attached to the left and right side surfaces of the rear part of the transmission 15, and are attached to both ends of the rear axle supported by the rear axle case. Rear wheels 17 and 17 are provided. In addition, a hydrostatic continuously variable transmission (hereinafter referred to as HST) 18 is provided at the front of the transmission 15, and an input shaft 18a of the HST 18 is a flywheel 20 of the engine 3, a universal joint, a transmission shaft 21, and the like. It is connected through.

  A front axle case 22 is swingably disposed at the front lower part of the body frame 2, 2, and a front axle is pivotally supported on the front axle case 22. The front axle protrudes from the left and right sides of the front axle case 22, and front wheels 23 and 23 are provided at both ends thereof.

  Thus, the driving force of the engine 3 is input from the fly hole 20 to the HST 18 via the transmission shaft 21 and is shifted in the HST 18 and then introduced into the transmission 15. It is transmitted to the rear axle of the axle case 16 and is also transmitted to the front axle of the front axle case 22 via the transmission shaft 24 so that the rear wheels 17 and 17 and the front wheels 23 and 23 are driven. . Further, the driving force of the engine 3 can be transmitted to the rear PTO shaft 25 disposed at the rear end portion of the transmission, and is configured to be able to drive a work machine attached to the rear end of the vehicle.

  Further, a hydraulic work machine lifting device 27 having a lift arm 26 is disposed on the upper surface of the transmission 15, and is attached to the lift arm 26 projecting rearward from the hydraulic work machine lifting device 27 and the rear part of the transmission 15. By the lower links 28 and 28 and the top link 29, the working machine can be mounted on the rear part of the machine body so as to be movable up and down.

Next, the configuration of the transmission 15 will be described.
As shown in FIG. 2, the transmission 15 is provided with a transmission case 31 having a front and rear half part (31a, 31b) having a front and rear split shape. The HST 18 is attached to the upper portion as a main transmission mechanism, and the input shaft 18a is supported to protrude forward from the housing 18b of the HST 18. Below the HST 18, the front wheel drive take-out shaft 32 protrudes and is supported from the lower part of the front surface of the front half 31 a of the transmission case 31.

  As described above, the front half 31a of the mission case 31 has a front wall at the front and an opening at the rear. In addition, the rear half portion 31b has a rear wall at the rear portion, the front portion is opened, a partition wall is formed at the front and rear middle portions, and the upper portion is opened. A PTO drive system and a sub-transmission mechanism, which will be described later, are accommodated above and below the first chamber C1 formed by joining the opening periphery of the front half 31a and the opening periphery of the rear half 31b. The second chamber C2 formed between the partition wall and the rear wall of the rear half part 31b accommodates a differential device 57, a suction strainer 90, and the like.

  The mission case 31 is filled with a certain amount of oil. This oil naturally lubricates shafts and gears arranged in a drive system, which will be described later, and is supplied to the HST 18 and the power steering device through the suction strainer 90. Being played as a hydraulic fluid.

  As shown in FIGS. 5 and 6, the suction strainer 90 includes a strainer portion 91 and support portions 92 and 93 provided on both sides of the strainer portion 91. It is configured to be inserted in the front-rear direction through the provided insertion hole 31 c and supported by the front and rear support portions 92 and 93. The front and rear support portions 92, 93 are made of a resin material, and the front support portion 92 is formed in a circular shape in cross section, while the rear support portion 93 is formed in a cross shape in cross section, The suction strainer 90 is easily grasped by the support portion 93.

  Further, in the rear support portion 93, protrusions 94, 94, 94, 94 are integrally formed at the rear ends of the orthogonal portions 93a, 93a, 93a, 93a, respectively. Thus, when the suction strainer 90 is taken out from the mission case 31 through the insertion hole 31c, the support portion 93 is slippery because oil is attached thereto, but the protrusions 94, 94, 94, 94 Since the finger can be hung, the suction strainer 90 can be easily taken out without sliding the hand with oil.

  A travel drive system in the transmission 15 will be described.

First, the HST 18 serving as the main transmission mechanism will be described.
A flat center section 33 is attached to a substantially upper half of the front wall surface of the front half 31 a of the mission case 31. To the center section 33, an opening peripheral portion of an HST housing 18b that houses a hydraulic pump 34 and a hydraulic motor 38 to be described later is attached. A pump-equipped surface is provided above the inner surface of the center section 33, and a motor-equipped surface is provided below the inner surface.

  An axial piston type hydraulic pump 34 is attached to the surface of the center section 33 with the pump. That is, the input shaft 18a also serving as a pump shaft is supported at the center of the surface with the pump, and the cylinder block 35 is fitted to the input shaft 18a so as not to be relatively rotatable. The cylinder block 35 is rotatable and slidable with respect to the surface of the center section 33 with the pump. A plurality of cylinder holes are formed in the cylinder block 35, and a piston 36 is fitted in each cylinder hole through a biasing spring so as to be slidable back and forth. The heads of the piston groups 36, 36,... Are in contact with the movable swash plate 37, and by changing the inclination angle of the movable swash plate 37, the stroke of the piston 36 is changed to make the discharge volume stepless. It is supposed to change to. The movable swash plate 37 is configured as a trunnion type, both of the trunnion shafts are supported on both side walls of the housing 18b, one of them is extended outside the housing 18b, and a control arm (not shown) is attached thereto. A shift lever is linked to the arm via a link mechanism.

  A hydraulic oil circulation oil passage for feeding the pressure oil discharged from the hydraulic pump 34 to an axial piston type hydraulic motor 38 to be described later is formed in the center section 33.

  The hydraulic motor 38 is attached to the motor-equipped surface of the center section 33. That is, a motor shaft 39 disposed in parallel below the input shaft 18a is supported at the center of the motor-equipped surface, and the cylinder block 40 is fitted to the motor shaft 39 so as not to be relatively rotatable. The cylinder block 40 is rotatable and slidable with respect to the motor mounting surface of the center section 33. The cylinder block 40 has a plurality of cylinder holes, and a piston 41 is energized in each cylinder hole. It is fitted through a spring so as to reciprocate. Then, the heads of the pistons 41, 41... Are brought into contact with the fixed swash plate 42, and the motor shaft 39 can be rotated at a speed corresponding to the discharge volume of the hydraulic pump 34. ing.

  The motor shaft 39 penetrates the center section 33 and the front wall of the front half 31a of the transmission case 31 and protrudes rearward, and its rear end is disposed in the first chamber C1. The output gear 45 is fixed to the front. A traveling output shaft 46 is pivotally supported in the mission case 31, and a clutch-type auxiliary transmission mechanism 50 is provided on the traveling output shaft 46.

Next, the auxiliary transmission mechanism 50 will be described.
A first input gear 51 is loosely fitted on the travel output shaft 46 and meshed with the output gear 45 on the motor shaft 39. A counter shaft 52 is supported in parallel with the travel output shaft 46, a transmission gear 53 is fixed on the counter shaft 52, and the transmission gear 53 is also meshed with the first input gear 51.

  A small diameter gear 54 is formed on the counter shaft 52, and a second input gear 55 loosely fitted on the travel output shaft 46 is engaged with the small diameter gear 54. Then, at a position sandwiched between the first input gear 51 and the second input gear 55, the travel output shaft is configured such that the clutch slider 56 is not rotatable relative to the travel output shaft 46 and is slidable in the axial direction. It is fitted on 46 via a clutch hub. The clutch slider 56 is linked to an auxiliary transmission lever disposed in the operating portion.

  Both the first input gear 51 and the second input gear 55 are formed with teeth that can engage with the clutch slider 56. In this way, by sliding the clutch slider 56 in the axial direction by operating the auxiliary transmission lever, the auxiliary transmission mechanism 50 selects either the high-speed rotation from the first input gear 51 or the reduced rotation of the second input gear 55. Thus, it is possible to obtain the traveling output shaft 46 in a neutral state where no rotation is transmitted.

  The driving force input to the travel output shaft 46 as described above is input to the input bevel gear 58 of the differential device 57 from the bevel gear 62 formed at the rear end of the travel output shaft 46, and the left and right rear powers. Drive the axle.

  A front wheel output gear 59 is fixed on the travel output shaft 46, and an intermediate gear 60 that is loosely arranged on the counter shaft 52 is engaged with the front wheel output gear 59. A front wheel transmission gear 61 is fixed on the front wheel drive take-out shaft 32 supported below the transmission case 31, and the intermediate gear 60 is engaged with the front wheel transmission gear 61. Thus, the rotation at the same speed as the travel output shaft 46 is transmitted to the front wheel drive take-out shaft 32 so that the front wheels 23 and 23 can be driven.

  A drive system for driving the rear PTO shaft will be described.

  The input shaft 18a of the HST 18 extends through the center section 33 and the front wall of the front half 31a of the transmission case 31 into the first chamber C1. An output gear 65 is fixed to the rear end of the input shaft 18a. One end of the PTO first transmission shaft 66 is inserted into a center hole provided in the output gear 65, and the transmission case 31 is connected to the transmission case 31 via a needle bearing. It is supported by the front wall of the front half part 31a. Thus, the PTO first transmission shaft 66 is disposed on the concentric shaft behind the input shaft 18a of the HST 18.

  The output gear 65 on the input shaft 18a is engaged with an input gear loosely fitted on a PTO drive main shaft (not shown) arranged in parallel with the PTO first transmission shaft 66, and the input gear and the PTO A PTO clutch is provided between the drive main shaft and a PTO transmission mechanism 67 is provided between the PTO drive main shaft and the PTO first transmission shaft 66. The PTO transmission mechanism 67 causes the PTO first transmission shaft 66 to be connected to the PTO drive main shaft. As a result, the driving force shifted to the PTO first transmission shaft 66 is obtained.

  A PTO second transmission shaft 68 is arranged on the concentric shaft behind the PTO first transmission shaft 66 and is integrally connected to the PTO first transmission shaft 66 via a coupling 69. The PTO second transmission shaft 68 extends to the vicinity of the rear end of the transmission case 31 and is linked to the rear PTO shaft 25 arranged in parallel with the PTO second transmission shaft 68 in a deceleration manner by gears 70 and 71. The rear PTO shaft 25 can be driven.

  Above the transmission 15 configured as described above, the hydraulic working machine lifting device 27 is disposed as described above. The hydraulic work machine elevating device 27 includes a hydraulic case 75 that accommodates a hydraulic cylinder. An opening is provided on the rear lower surface of the hydraulic case 75, and the peripheral edge portion of the opening is the rear half 31 b of the transmission case 31. It is attached to the opening peripheral part formed in the upper part. The front portion of the third chamber C3 formed in the hydraulic case 75 houses the piston 76 as a cylinder chamber, and is configured to rotate the lift arm 26 by sliding of the piston 76. Thus, in the hydraulic work machine lifting device 27, the third chamber C3 in the hydraulic case 75 is in communication with the second chamber C2 in the rear half 31b of the transmission case 31.

  An extraction pipe 80 for adjusting the internal pressure of the transmission case is provided above the hydraulic case 75. The extraction pipe 80 is formed by bending a cylindrical member into an inverted “L” shape, and an inner opening 80 a thereof is inserted into a hole formed in the upper surface of the hydraulic case 75. On the other hand, one end of the hose 81 is externally fitted and connected to the outer opening 80b, and the other end of the hose 81 extends forward and is connected to a member having a sealed space. It is externally fitted and connected to the communication portion 85 f formed in one of the steps 13. The sealed space has a large volume that can sufficiently cope with a change when the air in the mission case expands or contracts. In this embodiment, the take-out pipe is provided on the mission case. However, the take-out pipe may be provided on the outer peripheral surface of the mission case or above the oil level in the mission case.

  The structure which provided the communication part 85f in the left step 13L among the said left and right steps 13 is demonstrated. The right step is arranged substantially symmetrically with the left step 13L except that the communication portion 85f is provided, and the description thereof is omitted.

  As shown in FIG. 3, the left step 13L includes an upper layer forming portion 85a, a lower layer forming portion 85b, a connecting portion 85c connecting the upper layer forming portion 85a and the lower layer forming portion 85b, and an upper layer forming portion 85a and a lower layer forming. A hollow portion 85d formed in a sealed space by the portion 85b and the connection portion 85c, and a superposition portion 85e in which the upper layer formation portion 85a and the lower layer formation portion 85b are partially overlapped, and the fuselage at the superposition portion 85e The frame 2 is supported via a stay 2a. Here, the step 13L is formed by blow molding with a resin material, and can be manufactured easily at low cost.

  Then, either one of the left and right steps configured as described above, in this embodiment, the connecting portion 85c of the left step 13L is formed so that the cylindrical communication portion 85f projects rearward, and the inside and the outside communicate with each other. The front end of a hose 81 extending forward from the take-out pipe 80 is externally fitted and connected to the communication portion 85f. As a result, as shown in FIG. 4, the step 13L and the take-out pipe 80 are connected via the hose 81, and the hollow portion 85d of the step 13L and the second chamber C2 (the hydraulic case of the hydraulic case) The third chamber is in communication with the take-out pipe 80.

  In this way, by configuring the transmission case 31 and the step 13 to communicate with each other, when the temperature of the oil filled in the transmission case 31 rises, the air in the transmission case 31 is removed from the hydraulic case 75. The pipe 80 is fed into the step 13 through the hose 81, and the internal pressure of the mission case 31 is adjusted. And if the temperature of oil falls from this state, the air with which it filled in step 13 will be sent in into the mission case 31 from the extraction pipe 80 via the hose 81, and the internal pressure of the mission case 31 will be adjusted again. Become.

  Therefore, even if the internal pressure of the mission case 31 changes, the air in the sealed space can be adjusted by being expanded or compressed, so that the breather can be eliminated. Further, since air outside the extraction pipe 80 is not sent into the mission case 31 but air inside the step 13 is used, there is no need to expose the outer opening 80b of the extraction pipe 80 to the outside. At the same time, foreign matter can be reliably prevented from entering the mission case 31. For example, it is possible to prevent water from being mixed into the mission case 31 from the take-out pipe 80 during car washing using a large amount of water.

  The member connected to the take-out pipe may be any member having a sealed space. For example, a fender formed by blow molding with a resin material and the take-out pipe are connected by a hose, and the hollow portion formed in the fender is connected. Even if the sealed space and the second chamber in the latter half of the mission case are configured to communicate with each other, the same effect as described above can be obtained without interfering with existing devices.

The side view which shows the whole structure of the tractor which concerns on one Example of this invention. Side surface sectional drawing of a transmission. Side surface sectional drawing of a step. The side view which shows the structure of the body rear part. The side view of a suction strainer. The perspective view of a suction strainer.

Explanation of symbols

13 Step 15 Transmission 27 Hydraulic Work Equipment Lifting Device 31 Mission Case 75 Hydraulic Case 80 Extraction Pipe 81 Hose

Claims (2)

  A tractor characterized in that an extraction pipe is provided above the transmission case, and the inside of the transmission case and the sealed space provided on the fuselage are communicated with each other via the extraction pipe and the hose. The tractor according to claim 1, wherein the sealed space is configured as a step.

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