JPH11336873A - Hst type axle driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To direct transmit power between a motor shaft and axle by means of gears while an intermediate reduction gear train is eliminated in this HST type axle driving device. SOLUTION: A hydraulic pump P mechanism and a hydraulic motor M mechanism are provided for an oil passage body 3 in an L shape which is provided with a pump mounting surface 3a and a motor mounting surface 3b, in order to hydraulically connect a hydraulic pump P with a hydraulic motor M, a hydraulic circuit is formed in the hydraulic passage body 3 in an L shape, and concurrently, when the capacity of the hydraulic pump P is represented by X cm<3> , and the capacity of the hydraulic motor is represented by Y cm<3> , a relation between them shall be as follows; the capacity X cm<3> of the hydraulic pump < the capacity Y cm<3> of the hydraulic motor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an HST type axle drive device for driving a small work vehicle.

[0002]

2. Description of the Related Art Conventionally, as a technique relating to an HST type axle driving device, a technique as disclosed in Japanese Patent Application No. 1-309821 has been known. However, in the conventional technology, the hydraulic motor installed in the transmission case is
Since the displacement was configured to be the same as the displacement of the hydraulic pump, the rotation speed of the hydraulic motor was synchronized with the rotation speed of the hydraulic motor. Hydraulic pumps need to rotate at relatively high speeds in terms of transmission efficiency.If both pump and motor capacities are synchronized, the rotation speed of the hydraulic motor increases and decelerates to reach the axle. Therefore, a reduction mechanism constituted by an intermediate gear example was interposed between the motor shaft and the axle. Therefore, the distance between the hydraulic motor and the axle is increased, and the entire axle drive device is increased in size, the number of parts is increased, and the cost is increased because the bearing portion of the intermediate shaft must be processed into a case. Further, there was a problem that it took time to assemble.

[0003]

SUMMARY OF THE INVENTION The present invention is designed to eliminate the need for an intermediate reduction gear train and to enable direct gear transmission between a motor shaft and an axle. Conventionally, gear reduction is performed. The part is obtained by hydraulically decelerating between a small capacity hydraulic pump and a large capacity hydraulic motor.

[0004]

The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described. That is, it is a transmission case composed of a lower case 1 and an upper case 2, and an HST transmission is disposed inside the transmission case, and the HST transmission is configured as follows. Pump mounting surface 3a and motor mounting surface 3
b, an L-shaped oil passage body 3 is provided. On the pump mounting surface 3a of the L-shaped oil passage body 3, there is a discharge hydraulic pump P with a rotating cylinder block 4. A plurality of piston chambers are provided in the rotating cylinder block 4, a mechanism of a pump piston 8 reciprocating in the piston chamber is provided, and a motor rotating on the motor mounting surface 3b of the L-shaped oil passage body 3 is provided. Hydraulic motor M with case 5
The rotating motor case 5 is provided with a plurality of piston chambers, and each of the piston chambers is provided with a mechanism of a motor piston 9 of a hydraulic motor M that reciprocates therein. In order to hydraulically connect the hydraulic pump P and the hydraulic motor M, a hydraulic circuit is formed in the L-shaped oil passage body 3, and the capacity of the hydraulic pump P is set to Xcm.
³ and then, when the capacity of the hydraulic motor M and ycm ^3, an HST type transaxle apparatus characterized in that a capacitance Xcm, ³ <capacity cm ³ of the hydraulic motor M of the hydraulic pump P.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems to be solved and means to be solved by the present invention are as described above. Next, the configuration of the embodiment shown in the accompanying drawings will be described. FIG. 1 is a plan view of an axle driving device of the present invention with an upper case 2 removed, FIG. 2 is a rear cross-sectional view thereof, FIG. 3 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. FIG. 5 is a sectional view taken along the line CC of FIG. 1, FIG. 6 is a sectional view taken along the line BB of FIG. 1, FIG. 7 is a sectional view taken along the line DD of FIG. FIG. 8 is a hydraulic circuit diagram.

Referring to FIGS. 1, 2 and 3, the overall structure of the axle drive will be described. The transmission case is constructed by joining a lower case 1 and an upper case 2 up and down. Bearing portions of the axles 10L and 10R are supported on upper and lower joining surfaces of the lower case 1 and the upper case 2. In addition, the upper and lower joint surfaces of the lower case 1 and the upper case 2 are configured so that the joint surface of the lower surface of the upper case 2 is widened, and three L-shaped oils are used in this portion by three mounting bolts 51 from below. Road body 3 is attached.

The oil passage body 3 is provided with a pump mounting surface 3a having a surface in the same direction as the axle 10, and a motor mounting surface 3b having a surface perpendicular to the axle 10. The pump mounting surface 3a includes a pump shaft 38, a movable swash plate 6, a thrust bearing 6a, a pump piston 8, and a piston spring 27.
And a hydraulic pump P constituted by the cylinder block 4. The pump shaft 38 protrudes in a direction perpendicular to the axle 10, penetrates through the upper case 2 and protrudes upward, and receives power from an engine (not shown).

On the motor mounting surface 3b orthogonal to the pump mounting surface 3a, an output drive shaft 39 as a motor shaft, a fixed swash plate (ball bearing) 7, a motor piston 9, a piston spring 28, and a motor case 5 are provided. Hydraulic motor M is attached. Note that reference numeral 7a denotes a swash plate support held by the lower case 1.

Since the joint surface of the lower surface of the upper case 2 is configured to be wide, and the L-shaped oil passage body 3 is attached to the portion from below by a mounting bolt 51, the L-shaped oil passage body 3 is viewed from a side sectional view. After assembling the HST type transmission and the upper case 2 integrally, the lower case 1 is bonded to complete the assembly, and the L-shaped oil passage body is provided on both the lower case 1 and the upper case 2. It is easier to assemble than the case where 3 is supported. Further, since the number of the mounting bolts 51 for fixing the L-shaped oil passage body 3 to the joint surface on the lower surface of the upper case 2 is three, in the case of four, one bolt may float and cannot be fastened. In the case of the book, the front portion is in a fastening state, and the upper case 2 and the L-shaped oil passage body 3 can be fastened without any floating portion.

The three mounting bolts 51 are connected to the pump shaft 38.
Are arranged in parallel with each other, and the pump shaft 38 is located inside a triangle formed by the three. Therefore, the pump shaft 38, which is the portion where the power from the engine is transmitted in a vibrating state through a belt or the like, can be securely fixed by the three bolts, and the loosening of the mounting bolt 51 due to the vibration can be eliminated. You can. The pump mounting surface 3a provided on the L-shaped oil passage body 3 is a surface in the same direction as the joint surface between the upper case 2 and the lower case 3, and the motor mounting surface 3b is provided on the pump mounting surface 3a. The plane is orthogonal. Therefore, the pump shaft 38 of the hydraulic pump P
Is an axle 10.1 driven by an output drive shaft 39, which is a motor shaft, as a vertical shaft passing through the upper case 2.
0 is the lower case on the left and right. The horizontal axis can be set along the joint surface of the earth part case 2, and the direction of the axis can be set in accordance with the configuration of the HST-type axle drive device.

The output drive shaft 39, which is a motor shaft, projects in a direction parallel to the axle 10 and perpendicular to the pump shaft 38. The output drive shaft 39, which is a motor shaft, is also connected to the lower case 1 and the upper case 1. The shaft center is located on the joint surface with the case 2, and a bearing is interposed on the joint surface. A brake device constituted by a brake drum 31 and a brake band 30 is disposed at a portion where the output drive shaft 39 as the motor shaft projects from the transmission case,
The brake device is covered with a brake case 29.

Further, a small motor output gear 42 is formed integrally with the output drive shaft 39 which is a motor shaft, and the small motor output gear 42 of the differential gear device 40 formed on the axles 10L and 10R. It is in mesh with the large input gear 41. As shown in FIG. 8, the oil passage plate 3 is provided with a pair of kidney ports, a pair of oil passages, and a suction hole for connecting the hydraulic pump P and the hydraulic motor M. Equipped with valves 50 and 51. In addition, the motor mounting surface 3b is formed to have a larger area than the pump mounting surface 3a.

In the above configuration, the present invention sets X <Y, where the capacity of the hydraulic pump P is Xcm ³ and the capacity of the hydraulic motor M is Ycm ³ . That is, by reducing the capacity of the hydraulic pump P and increasing the capacity of the hydraulic motor M, the number of rotations of the hydraulic motor M becomes X / Y with respect to the number of rotations 1 of the hydraulic pump P, and HS
Hydraulic deceleration can be performed in the portion of the T transmission. Therefore, the deceleration can be performed only by changing the sizes of the conventional hydraulic pump P and the hydraulic motor M without interposing a gear type reduction device as in the related art. From this, the rotational speed itself of the small motor output gear 42 provided on the output drive shaft 39, which is the motor shaft, is low. Ten rotations are obtained.

As shown in FIGS. 1 and 2, between the lower surface of the oil passage body 3 and the inner surface of the lower case 1, an oil for sucking lubricating oil in the transmission case as hydraulic oil for the HST transmission. A filter 26 is provided. The working oil sucked from the oil filter 26 can be supplied to a closed circuit between the hydraulic pump P and the hydraulic motor M by a check valve interposed in the oil passage inside the oil passage body 3.

Push the check valve of the supply circuit
When the vehicle is stopped, the discharge pressure of the hydraulic motor M driven from the axle 10 is released or the HST transmission is completely stopped when the vehicle is stopped. It constitutes a pressure oil release mechanism that can obtain a neutral state. The push rod 46/4
The pressing arm 37 presses the pressing arm 37, and the pressing arm 37 is configured to be pressed by an eccentric pin 36 attached to the operation shaft 35.

A pressure release arm 34 is attached to a portion where the operation shaft 35 protrudes upward from the upper case 2, and a detent projection which engages at an operation position is formed on a lower surface of the pressure release arm 34. A detent groove is formed in the boss hole portion of the upper case 2. A biasing spring 43 is interposed around the operation shaft 35 so that the detent protrusion and the groove engage with a constant pressure. When the pressure release arm 34 is returned to its original position, the pressing arm 37 is retracted, and the pressing rods 46 and 47 are moved.
Is returned to the direction in which the check valve is closed by the biasing springs 48 and 49.

As shown in FIGS. 2 and 6, on the upper surface of the upper case 2, an oil plug 32, an inspection rod 33 extending below the oil plug 32, and a breather plug 50 are attached. A breather opening 2b is formed in the upper case 2 below the breather plug 50. The upper surface of the upper case 2 is partially formed higher than the oil level (OL) in the case so that the lubricating oil and hydraulic oil in the case does not overflow out of the case when thermally expanded. I have.

Next, a description will be given of a shift operation mechanism for operating the movable swash plate 6 of the hydraulic pump P and a brake operation system for operating the brake band 30 in the axle drive device of this configuration. In FIG. 4, a speed change link 16 connected to a speed change pedal of the vehicle is pivotally connected to an end of the speed change arm 12 at an upper end of an arm shaft 23. When the operator depresses the transmission pedal to either the front or the rear, the transmission arm 12 rotates back and forth across the neutral position via the transmission link 16,
As shown in FIG. 3, the swash plate operation arm 11 at the lower end of the arm shaft 23 is provided.
Rotates. A gear lever 2 is attached to the tip of the swash plate operation arm 11.
The speed lever 25 is fitted in the guide groove of the movable swash plate 6, and rotates the movable swash plate 6 forward or backward. The swash plate operation arm 1
At the tip of 1, there is provided a detent slot 11a,
The detent ball 44 pressed by the detent spring 45 fits into the detent slot a, and the swash plate operation arm 11
To ensure the neutral position.

The brake device is a brake link 1
Reference numeral 3 is connected to a brake pedal of the vehicle, and when the brake pedal is depressed, the interlocking arm 14 pivotally supported by the shaft 24 is rotated. The interlocking arm 14
Of the transmission arm 12 is loosely fitted into the cam hole 12a of the transmission arm 12, and when the brake pedal is depressed and the transmission arm 12 is in a position other than neutral, the coupling pin 21 is inserted into the cam hole 12a. To the right to return the shifting arm 12 to the neutral position. The cam hole 12a
Is configured to return the speed change arm 12 to the neutral position by the interlocking pin 21 in both cases when the speed change arm 12 is moving forward or backward.

When the brake pedal is depressed, the interlocking arm 14 turns. However, the turning of the interlocking arm 14 prevents the brake device from immediately starting braking. Hole 14a
Are formed as long holes. Since the pivot hole 14a is formed as a long hole, the brake is started after the transmission arm 12 is returned to the neutral side to a certain extent.
The shaft 24 is pivotally supported by the protrusion 2c of the upper case 2.

The distal end of the connecting link 15 is pivotally connected to one end of a buffer arm 18 pivotally supported by a pivot 19 of a projection 2a at the rear end of the upper case 2. The buffer arm 18
An engagement protrusion 18a is integrally formed at the other end of the
The lower end of the torque spring 17 is engaged with the engaging projection 18a. The upper end of the torque spring 17 is fitted into an elongated hole 20b of the brake arm 20, which is shown in its entirety in FIG. The brake arm 20 is driven by the torque spring 17 to rotate the shaft 20a.
, The brake band 30 fitted to the pin 20c at the other end is pulled, and the brake drum 3
1 is brake-pressed.

In this configuration, the torque spring 17 is configured as a two- or three-turn winding spring whose ends cross vertically as shown in FIG. 4 in plan view. Since the torque spring 17 is interposed between the buffer arm 18 and the brake arm 20, the depressing force of the brake pedal does not directly become the pressing and holding force of the brake band 30, and the brake force is applied by the spring force of the torque spring 17. It is configured to hold 30.

[0023]

As described above, the present invention has the following advantages. According to the first aspect, the present invention is directed to a transmission case constituted by a lower case 1 and an upper case 2, wherein an HST transmission is arranged inside the transmission case, and the HST transmission is configured as follows. An L-shaped oil passage body 3 having a pump attachment surface 3a and a motor attachment surface 3b is provided, and a discharge type having a rotating cylinder block 4 on the pump attachment surface 3a of the L-shaped oil passage body 3. A plurality of piston chambers are provided in the rotating cylinder block 4, and a mechanism of a pump piston 8 reciprocating is provided in the piston chamber. There is a hydraulic motor M with a rotating motor case 5 on the motor mounting surface 3b. The rotating motor case 5 is provided with a plurality of piston chambers,
Each piston chamber is provided with a mechanism of a motor piston 9 of a hydraulic motor M that reciprocates therein.
Further, in order to hydraulically connect the hydraulic pump P and the hydraulic motor M, a hydraulic circuit is formed in the L-shaped oil passage body 3. The capacity of the hydraulic pump P is set to Xcm ^3, and When ycm ³ capacity, and the capacity Xcm, ³ <capacity ycm ³ of the hydraulic motor M of the hydraulic pump P. Therefore, first, between the hydraulic pump P and the hydraulic motor M,
Since the first deceleration can be performed, the number of reduction stages by gears can be reduced. Therefore, the intermediate reduction gear train is eliminated, and the gear can be directly transmitted between the motor shaft and the axle. Therefore, the gear reduction portion interposed in the prior art is eliminated, and the output drive shaft 39 which is the motor shaft is eliminated. Since the axle 10 and the axle 10 can be brought closer to each other, the overall configuration of the axle drive device can be reduced in size. In addition, since the bearing portion of the countershaft of the conventional intermediate reduction gear device is no longer required, the need for machining the bearing hole case is eliminated. Furthermore, since the reduction gear device could be omitted, the number of parts could be reduced, and the number of assembly steps and time could be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of an axle drive device of the present invention with an upper case 2 removed.

FIG. 2 is a rear sectional view of the same.

FIG. 3 is a sectional view taken along the line AA of FIG. 1;

FIG. 4 is a plan view of a link portion for a shift operation and a brake operation.

FIG. 5 is a sectional view taken along a line CC in FIG. 1;

6 is a sectional view taken along the line BB of FIG. 1;

FIG. 7 is a sectional view taken along the line DD in FIG. 1;

FIG. 8 is a hydraulic circuit diagram.

[Explanation of symbols]

 P Hydraulic pump M Hydraulic motor 1 Lower case 2 Upper case 3 Oil passage 4 Cylinder block 5 Motor case 6 Movable swash plate 39 Output drive shaft

Claims (1)

[Claims] 1. A transmission case comprising a lower case 1 and an upper case 2, wherein an HST transmission is arranged inside the transmission case, and the HST transmission is configured as follows. Pump mounting surface 3a and motor mounting surface 3
An L-shaped oil passage body 3 having a b is provided. On the pump mounting surface 3a of the L-shaped oil passage body 3, there is a discharge hydraulic pump P with a rotating cylinder block 4. A plurality of piston chambers are provided in the rotating cylinder block 4, a mechanism of a pump piston 8 reciprocating is provided in the piston chamber, and a motor rotating on the motor mounting surface 3 b of the L-shaped oil passage body 3. There is a hydraulic motor M with a case 5, a plurality of piston chambers are provided in the rotating motor case 5, and each piston chamber has a mechanism of a motor piston 9 of the hydraulic motor M reciprocating therein. And a hydraulic circuit is formed in the L-shaped oil passage body 3 to hydraulically connect the hydraulic pump P and the hydraulic motor M, and the capacity of the hydraulic pump P is Xcm ³ , Hydraulic module When the capacity of the motor M and ycm ^3, the capacity of the hydraulic pump P Xc
An HST-type axle driving device, wherein m ³ <capacity cm ³ of the hydraulic motor M.