JP4279518B2 - Work vehicle transmission structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission structure of a work vehicle used for transportation of various equipment and materials for agricultural work and light civil engineering work, or for movement of personnel.
[0002]
[Prior art]
As a transmission structure of the work vehicle, for example, as disclosed in Japanese Patent Application Laid-Open No. 2000-103246, one using a belt-type continuously variable transmission (belt converter) for traveling speed change is known. .
[0003]
[Problems to be solved by the invention]
A belt-type continuously variable transmission can be manufactured at a relatively low cost and can perform a smooth continuously variable transmission. However, since it is a continuously variable transmission within the belt winding ratio change range, The vehicle cannot start from a high speed or travel at a slow speed, and it is necessary to equip a separate forward / reverse switching gear mechanism, which complicates the mission structure.
The belt-type continuously variable transmission must take measures for dust prevention and cooling, and maintenance such as belt replacement is indispensable.
[0004]
The present invention has been made paying attention to such points, and it is a main object of the present invention to provide a transmission structure that is excellent in speed change operability, durability, and maintainability and can be effectively used in a work vehicle. It is what.
[0005]
[Means for Solving the Problems]
[Configuration, Action, and Effect of Invention of Claim 1]
[0006]
According to a first aspect of the present invention, there is provided a transmission structure for a work vehicle, in which a transmission case is provided at a rear portion of a traveling vehicle body including front wheels and rear wheels, and a hydraulic continuously variable transmission that can shift forward and reverse is provided in the transmission case. And an engine having a crankshaft centered in the front-rear direction in front of the transmission case, and the pump input shaft of the continuously variable transmission is connected to the pump input shaft via a shaft transmission mechanism. Configured to transmit power from the engine,
The transmission case is equipped with a sub-transmission mechanism, a differential device, and left and right rear wheel drive output shafts for shifting the shift power from the continuously variable transmission to a plurality of stages, and the left and right rear wheel drive outputs. The shaft and the left and right rear wheels are linked and connected by a pair of universal joints and a transmission shaft, respectively.
The main frame constituting the vehicle body frame is configured in a stepped manner in which the frame part of the rear part of the vehicle body is positioned higher than the frame part of the front part, and the frame part positioned higher than the rear part of the vehicle body and the lower part in front of this. A mission support frame that is substantially L-shaped in side view across the frame portion and is narrower than the lateral width of the frame portion at the rear of the vehicle body. It is connected via a vibration isolator to the mission support frame to support the lower side of the mission case equipped with the hydraulic continuously variable transmission,
Separately from the transmission support frame, the left and right rear wheels are provided with a leaf spring and one end at a rear portion of the vehicle body that are provided between a frame portion positioned at a higher position of the rear portion of the vehicle body and a frame portion positioned at a lower position ahead of the vehicle body. The rear wheel is supported so as to be vertically displaceable with respect to the vehicle body frame by being supported by a bearing block supported by a shock absorber attached to the frame portion positioned at the higher position .
[0007]
According to the above configuration, the hydraulic continuously variable transmission can change the amount and direction of the oil discharged from the variable displacement pump to start from zero speed, switch at low speed, switch between forward and backward, and move forward and backward. The stepless speed change can be arbitrarily performed. Further, the rear wheel speed can be significantly changed by shifting the shift power to a plurality of stages by the auxiliary transmission mechanism.
And, the hydraulic continuously variable transmission does not wear the transmission member like the belt type and does not require maintenance such as component replacement.
[0008]
According to the above configuration, by setting the specifications of the universal joint and transmission shaft, it is possible to realize rear wheel drive corresponding to the tread and suspension form of the rear wheel, and it is highly versatile as a transmission structure for work vehicles It will be a thing.
[0009]
Therefore, according to the invention of claim 1, it is excellent in speed change operability, durability and maintainability, and can be effectively used as a transmission structure of a work vehicle.
[0010]
[Configuration, Action, and Effect of Invention of Claim 2]
[0011]
According to a second aspect of the present invention, there is provided a transmission structure for a work vehicle according to the first aspect, wherein the continuously variable transmission is configured as a transmission integrated type in which a pump and a motor are incorporated in a casing portion formed in a transmission case. is there.
[0012]
According to the above configuration, since a part of the transmission case becomes the casing of the continuously variable transmission, the case structure is simplified and assembled compared to the case where the continuously variable transmission is configured separately and connected to the transmission case. The workability can be improved and the cost can be reduced.
[0013]
[0014]
[Configuration, operation, and effect of inventions according to claims 3 and 4]
[0015]
According to a third aspect of the present invention, there is provided the transmission structure for a work vehicle according to the first or second aspect, wherein a front wheel drive output shaft is projected from the front surface of the transmission case.
[0016]
According to a fourth aspect of the present invention, there is provided the work vehicle transmission structure according to the third aspect, wherein when the front wheel drive system starts to rotate at a higher speed than the rear wheel drive system, power transmission to the front wheel drive system is interrupted. It is configured.
[0017]
According to the above configuration, a work vehicle with front and rear wheel drive specifications can be easily configured. If the power take-out from the front-wheel drive output shaft is configured to be intermittent, it is convenient that the front-and-rear wheel drive mode and the rear-wheel drive mode can be arbitrarily used according to the traveling road surface.
[0018]
[Configuration, Action, and Effect of Invention of Claim 5]
[0019]
According to a fifth aspect of the present invention, there is provided the transmission structure for a work vehicle according to any one of the first to fourth aspects, wherein an opening for power extraction is provided in the transmission case, and the pump in the continuously variable transmission is provided from the opening. A power take-out device for taking out the rotational power of the input shaft as work power is detachably attached to the transmission case.
[0020]
According to the above configuration, for example, in a work vehicle with a hydraulic option, the power take-off device can be attached to the transmission case to drive the hydraulic pump, and in a work vehicle with no hydraulic option, It is only necessary to remove the take-out device and close the opening with a lid cover or the like, so that the versatility as a transmission structure of the work vehicle is high.
[0021]
[Configuration, Action, and Effect of Invention of Claim 6]
[0022]
According to a sixth aspect of the present invention, there is provided a transmission structure for a work vehicle according to any one of the first to fifth aspects, wherein the wet structure acts on the left and right rear wheel drive output shafts on the left and right sides of the transmission case. Equipped with multi-plate type rear wheel brake.
[0023]
According to the above configuration, the wet-type multi-plate rear wheel brake is more durable than the drum brakes that are widely used in this type of work vehicle brake, and there is almost no deterioration in performance due to wear. A stable braking function can be exhibited even in a work vehicle used in the above.
[0024]
[Configuration, operation, and effect of invention of claim 7]
[0025]
According to a seventh aspect of the present invention, there is provided the transmission structure for a work vehicle according to the sixth aspect, wherein a brake case is connected to the left and right of the transmission case, and the rear wheel drive output shaft and the rear wheel brake are connected to the brake case. Is configured to be mountable in a pre-assembled manner.
[0026]
According to the above configuration, the friction plate group constituting the rear wheel brake and the output shaft for driving the rear wheel are assembled in advance in the brake case in a separate process, and this may be assembled in the transmission case. Compared to the case where all parts are assembled directly, the assembly workability is high, which is effective for improving the production efficiency.
[0027]
[0028]
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Entire side of the working vehicle according to the present invention in FIG. 1, the overall plan is shown respectively in FIG. This work vehicle includes a two-seater specification driving unit 4 at a front and rear intermediate portion of a four-wheel traveling vehicle body 3 having left and right front wheels 1 to be steered and left and right rear wheels 2 fixed in direction. At the same time, the vehicle is configured as a four-wheel drive vehicle provided with a rear loading unit 5 behind the operation unit 4. In this example, a dump bed 6 is provided on the rear loading unit 5.
[0030]
3 to 7 show the frame structure of the traveling vehicle body 3. The main frame 7 of the traveling vehicle body 3 includes a pair of left and right front main frames 7a made of a square pipe material, and a rear main frame 7b connected to the rear end of the main frame 7 via a vertical frame 7c. The main frame 7 is connected to the front frame 8, the driving unit frame 9, the seat support frame 10, the engine mounting frame 11, the mission support frame 12, and the like, and is erected on the left and right above the front end of the driving unit frame 9. A protective frame 15 that covers the operating unit 4 is attached across the front mast 13 of the sheet metal structure and the rear mast 14 made of pipe standing on the left and right of the rear end of the operating unit frame 9.
[0031]
The protective frame 15 is composed of a pair of left and right portal frames 15a connected to the front mast 13 and the rear mast 14, and a plurality of stays 15b connecting them, as indicated by phantom lines in FIG. In addition, a sunshade 16 is attached to the upper end of the protective frame 15 as necessary.
[0032]
A front cover 17 is attached to the front of the vehicle body. The front cover 17 includes a lower cover 17 a that covers the front frame 8 from the front and left and right sides, and a front upper cover 17 b that covers the front frame 8, the upper part of the operating unit frame 9, and the front mast 13. In the front cover 17, a radiator 18 with an electric fan connected to an engine 30 described later is accommodated. A step 20 is stretched under the front main frame 7a and the driving unit frame 9, and various operation levers such as a steering handle 21 and a front panel are mounted on the driving unit frame 9. . A driver's seat 22 and a passenger's seat 23 are mounted on the seat support frame 10 so as to be able to lift and rotate, and a driver rear cover 24 that covers the seat support frame 10 and the rear mast 14 is provided.
[0033]
The left and right engine mounting frames 11 are mounted and supported by front and rear, left and right vibration-proof rubbers (not shown) on the engine 30 with the crankshaft centered in the front-rear direction, and a transmission case 31 is connected to and supported by the transmission support frame 12. A hydraulic continuously variable transmission 32 that receives engine power is provided at the front of the transmission case 31.
[0034]
As shown in FIGS. 9 to 11, the mission support frame 12 is pivotally coupled across brackets 33 a and 34 a of horizontal frames 33 and 34 that are horizontally mounted on the lower front portion and the upper rear portion of the main frame 7. The rubber bushes 35 are inserted into the shaft support connecting portions at both ends of the frame so that the transmission vibration is absorbed.
[0035]
As shown in FIGS. 12 and 13, the continuously variable transmission 32 includes an axial plunger type variable displacement pump 36 and an axial plunger type fixed displacement motor 37 in a casing part formed integrally with the front portion of the transmission case 31. It has a structure in which it is assembled side by side and closed from the front by the port block 38, and the motor 36 is changed by changing the swash plate angle of the pump 36 and changing the direction and amount of pressure oil supplied from the pump 36 to the motor 37. The output shaft 39 is configured to continuously change in a forward and reverse direction. Then, the pump input shaft 40 is driven in conjunction with the engine 30 via a shaft transmission mechanism 42 having a pair of universal joints 41 interposed therebetween, and the shifting power extracted from the motor output shaft 39 is input to the mission case 31. Are transmitted to the left and right rear wheels 2, and part of the transmission power is transmitted to the front differential device 45 via the universal joint 43 and the transmission shaft 44 to drive the left and right front wheels 1. ing.
[0036]
The continuously variable transmission 32 uses the lubricating oil stored in the transmission case 31 as hydraulic oil, pressurizes the oil taken out via the strainer 46 with the charge pump 47, and the charge oil passage of the continuously variable transmission 32. The drain oil is reduced into the mission case 31. The upper surface of the transmission case 31 is provided with an oil filter 48 for purifying charge oil, and the shaft transmission mechanism 42 is provided with a fan 49 for cooling the continuously variable transmission 32.
[0037]
The transmission case 31 is provided with a gear-type sub-transmission mechanism 50 that shifts the power from the motor output shaft 39 in two steps of high and low in a constant mesh form. That is, the subtransmission mechanism 50 is provided between the first shaft 51 that is gear-linked to the motor output shaft 39 and the second shaft 52 that is disposed confrontingly with the motor output shaft 39. By shifting the shift sleeve 53 splined on the two shafts 52 to the right in FIG. 12 and meshing with the bosses of the large-diameter gear 54 loosely fitted on the first shaft 51, the motor output is transmitted between the gears 55 and 56. The second shaft 52 can be driven at a low speed by the deceleration between the gears 57 and 54, and the shift sleeve 53 is shifted to the left in FIG. 12 and directly meshed with the motor output shaft 39. Thus, the second shaft 52 is driven at a high speed.
[0038]
The power shifted by the sub-transmission mechanism 50 having the above configuration is transmitted from the second shaft 52 to the bevel pinion shaft 60 via the gears 58 and 59 and then the differential device 62 with a differential lock via the bevel pinion gear 61. Is extracted from the left and right rear wheel drive output shaft 63 which is the differential shaft of the differential device 62. The left and right rear wheels 2 are pivotally supported via a bearing block 66 supported by a leaf spring 64 and a shock absorber 65, and linked to the rear wheel drive output shaft 63 via a pair of universal joints 67 and a transmission shaft 68. Has been.
[0039]
A brake case 69 is assembled to the left and right sides of the mission case 31. The brake case 69 is provided with a rear wheel drive output shaft 63 and a multi-plate type rear wheel brake 70. The rear wheel brake 70 brakes the output wheel 63 for driving the rear wheel by pressing the friction plate 71 group interposed between the output shaft 63 for driving the rear wheel and the inner surface of the brake case 69 with the pressing plate 72. The operation of the operation shaft 73 mounted on the brake case 69 and the rotation of the pressing plate 72 around the output shaft axis cause the pressing plate 72 to rub due to the action of the ball cam 74. The plate 71 group is pressed or released to apply or release braking force to the rear-wheel drive output shaft 63.
[0040]
When assembling, the rear wheel drive output shaft 63 is pre-assembled to the brake case 69 together with the brake components, and the pre-assembled brake case 69 is attached to the left and right side surfaces of the transmission case 31. The differential device 62 is supported between the brake cases 69.
[0041]
The power of the bevel pinion shaft 60 is transmitted to the front wheel drive output shaft 80 via the shift gear 76, the idle gear 77, the clutch gear 78, and the clutch sleeve 79 that is spring-engaged and engaged with the clutch gear 78. The power extracted from the front wheel drive output shaft 80 is transmitted to the front differential device 45 through the transmission shaft 44 as described above, and the front wheel 1 is driven at a speed synchronized with the rear wheel 2. Here, when the front wheel drive system is reversely driven during turning and starts rotating at a higher speed than the rear wheel drive system, the clutch sleeve 79 is automatically retracted from the clutch gear 78 to transmit power to the front wheel drive system. Is refused. Further, by manually operating the shift gear 76 so as to be disengaged from the idle gear 77, it is possible to obtain a two-wheel drive state in which the driving of the front wheels 1 is stopped and only the rear wheels 2 are driven to travel.
[0042]
The left and right front wheels 1 are pivotally supported by a front axle case 85 that is independently suspended via a suspension mechanism 84. As shown in FIG. 15, the suspension mechanism 84 extends from the vehicle body frame so as to be swingable up and down. A suspension arm 81, a suspension spring 82, a shock absorber 83, and the like are included. A front axle 87 mounted on the front axle case 85 and a transmission shaft 86 extending from the front differential device 45 are connected by a ball-type shaft joint 88, and a flange 87a provided at the outer end of the front axle 87 is provided. The front wheel 1 can be attached to the front.
[0043]
The left and right front axle cases 85 are also used as brake cases, and front wheel brakes 90 are respectively incorporated therein. The front wheel brake 90 is constructed in a wet multi-plate type so as to brake the front axle 87 by pressing a friction plate 91 group interposed between the front axle 87 and the inner surface of the front axle case 85 by a ring-shaped piston 92. The piston 92 is advanced and displaced in the braking direction by the pressure oil supplied through the pipe 93, and is returned and displaced in the braking release direction by the return spring 94 and the pressing plate 95. The backward return position of the piston 92 can be changed by adjusting the advance / retreat of the adjusting bolt 96, and this adjustment minimizes the play of the piston 92 when braking and increases the response of the braking operation. Be able to. Further, the front axle case 85 is formed with another oil storage chamber 97 that is connected to the brake chamber in an annular shape in order to secure the amount of lubricating oil retained in the case and sufficiently ensure the lubricating oil life. Yes.
[0044]
FIG. 16 shows a brake operation system. An operation lever 73 a is provided at the outer end of the operation shaft 73 for operating the left and right rear wheel brakes 70. A pair of hydraulic cylinders 100 that push and pull each operation lever 73 a are operated by the brake pedal 101. Connected to a master cylinder 102 via a pipe 103. The master cylinder 102 and the front wheel brake 90 are connected by the pipe 93, and the left and right front wheels 1 and the rear wheel 2 can be braked simultaneously by depressing the brake pedal 101. The operation lever 73a is linked to the parking lever 104 via an operation wire 105, a stabilizer link 106, and left and right brake wires 107. When parking, the parking lever 104 is operated to brake the left and right rear wheels 2. Can be kept.
[0045]
As shown in FIG. 13, a power extraction gear 107 is provided at the rear end of the pump input shaft 40 of the continuously variable transmission 32 provided in the mission case 31, and an opening 108 formed on the upper surface of the mission case 31 is provided. A power take-out device 109 is installed. The power take-out device 109 includes gears 110 and 111 meshing with the gear 107 in the case and a rear-side power take-out shaft 112, and the hydraulic pump 113 is driven by the taken-out power. .
[0046]
The hydraulic pump 113 is used as a pressure oil source for a dump cylinder (not shown) that moves up and down the loading platform 6, and is manually operated by suctioning the hydraulic oil stored in the hydraulic oil tank 114 disposed below the left seat. As shown in FIGS. 17 to 19, a metal pipe 116 that is supplied to the control valve 115 and led out from the control valve 115 is provided along the main frame 7 and connected to the coupler 117. And the dump cylinder will be connected by a hydraulic hose. Further, it is also possible to use another hydraulically driven implement connected to the coupler 117 by piping.
[0047]
Here, the hydraulic oil tank 114, the control valve 115, the pipe 116, and the support bracket 118 of the coupler 117 are tightened and held at appropriate positions on the main frame 7 by U bolts 119 and clamp fittings 120. These models are not installed on models that do not have a hydraulic option. If there is a request to equip the hydraulic option at a later date, the hydraulic equipment can be easily installed as described above. When the hydraulic option is not installed, the power take-out device 109 and the hydraulic pump 113 are removed from the mission case 31 and the opening 108 is closed with the lid cover 121 as shown in FIG.
[0048]
[Another embodiment]
The present invention can also be implemented in the following forms.
(1) In the above-described embodiment, the continuously variable transmission 32 is integrated with the transmission case 31. However, the continuously variable transmission 32 is configured separately and connected to the transmission case 31. You can also.
(2) The opening 108 for taking out the power of work can be provided on the lateral side surface of the upper part of the mission case 31.
(3) A liquid tank, a harvested hopper, or the like may be provided in the rear loading unit 5.
(4) An auxiliary seat may be installed in the rear stacking unit 5 so as to constitute a work vehicle having specifications that allow several persons to board and move.
[Brief description of the drawings]
[Fig. 1] Overall side view of a work vehicle [Fig. 2] Overall plan view of the work vehicle [Fig. 3] Overall side view showing the vehicle body structure of the work vehicle [Fig. 4] Overall perspective view of the frame structure [Fig. [Fig. 6] Perspective view showing a part of the frame structure [Fig. 7] Perspective view showing the frame structure and the upper attachment member [Fig. 8] Plan view of the transmission structure [Fig. 9] Side view of the mission case [Fig. FIG. 10 is a vertical side view showing the rear end connecting portion of the mission support frame. FIG. 11 is a vertical rear view thereof. FIG. 12 is a cross-sectional plan view showing the internal structure of the mission case. Side view [Fig. 14] Vertical side view showing the front of the transmission case when the power take-off device is removed [Fig. 15] Vertical rear view of the front wheel shaft support [Fig. 16] Configuration diagram of the brake operation system [Fig. Oblique showing piping structure Figure a-a sectional view in FIG. 18 is a side view showing a hydraulic piping structure [19] Figure 18 [EXPLANATION OF SYMBOLS]
DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 3 Traveling vehicle body 7 Main frame 12 Mission support frame 30 Engine 31 Transmission case 32 Continuously variable transmission 36 Pump 37 Motor 40 Pump input shaft 50 Subtransmission mechanism 62 Differential device 63 Rear wheel drive output shaft 64 Leaf spring 65 Shock absorber 67 Universal joint 68 Transmission shaft 70 Rear wheel brake 108 Opening 109 Power take-out device

Claims (7)

A transmission case is arranged at the rear of the traveling vehicle body with front wheels and rear wheels. The transmission case is equipped with a hydraulic continuously variable transmission that can shift forward and reverse, and a crankshaft center in front of the transmission case. The engine and the pump input shaft of the continuously variable transmission are connected via a shaft transmission mechanism to transmit power from the engine to the pump input shaft.
The transmission case is equipped with a sub-transmission mechanism, a differential device, and left and right rear wheel drive output shafts for shifting the shift power from the continuously variable transmission to a plurality of stages, and the left and right rear wheel drive outputs. The shaft and the left and right rear wheels are linked and connected by a pair of universal joints and a transmission shaft, respectively.
The main frame constituting the vehicle body frame is configured in a stepped manner in which the frame part of the rear part of the vehicle body is positioned higher than the frame part of the front part, and the frame part positioned higher than the rear part of the vehicle body and the lower part in front of this. A mission support frame that is substantially L-shaped in side view across the frame portion and is narrower than the lateral width of the frame portion at the rear of the vehicle body. It is connected via a vibration isolator to the mission support frame to support the lower side of the mission case equipped with the hydraulic continuously variable transmission,
Separately from the transmission support frame, the left and right rear wheels are provided with a leaf spring and one end at a rear portion of the vehicle body that are provided between a frame portion positioned at a higher position of the rear portion of the vehicle body and a frame portion positioned at a lower position ahead of the vehicle body. A work vehicle transmission structure in which the rear wheel is supported so as to be vertically displaceable with respect to the vehicle body frame by being supported by a bearing block supported by a shock absorber attached to the frame portion positioned at the higher position .   2. The transmission structure for a work vehicle according to claim 1, wherein the continuously variable transmission is configured as a transmission integrated type in which a pump and a motor are incorporated in a casing portion formed in a transmission case.   The work vehicle transmission structure according to claim 1, wherein a front-wheel drive output shaft projects from a front surface of the transmission case.   The transmission structure for a work vehicle according to claim 3, wherein power transmission to the front wheel drive system is cut off when the front wheel drive system starts rotating at a higher speed than the rear wheel drive system.   An opening for taking out power is provided in the transmission case, and a power take-out device for taking out the rotational power of the pump input shaft in the continuously variable transmission as working power from the opening is detachably attached to the transmission case. The transmission structure of the work vehicle as described in any one of 1-4.   The work vehicle according to any one of claims 1 to 5, wherein a wet multi-plate type rear wheel brake acting on the left and right output shafts for driving the rear wheels is provided on the left and right sides of the transmission case. Transmission structure.   The transmission structure for a work vehicle according to claim 6, wherein a brake case is connected to the left and right sides of the transmission case, and the rear wheel drive output shaft and the rear wheel brake can be attached to the brake case in a pre-assembled manner.

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