JPH03242469A - Circumscribed gear type oil hydraulic motor - Google Patents

Abstract

PURPOSE:To concurrently serve for both a drive torque generating device and a differential limiting device by fixing one of the two circumscribed gears, connected to the first supporting shaft, thereto and a circumscribed gear, meshed with the circumscribed gear float-fitted to the first supporting shaft, of the two circumscribed gears, connected to the second supporting shaft, thereto. CONSTITUTION:An output of circumscribed gears 24, 25 in one row is transmitted to the first supporting shaft 28 to which the circumscribed gear 24 is fixed, and an output of circumscribed gears 26, 27 in the other row is transmitted to the second supporting shaft 29 to which the circumscribed gear 27 is fixed. When an oil hydraulic motor 34 thus obtained is applied to a vehicle driving gear, the circumscribed gears 24, 25 and 26, 27 in the two rows are rotated at an equal speed in the case of rotating drive wheels, connected to the supporting shafts 28, 29, at an equal speed. When racing is generated in one of the supporting shafts 28, 29 by a slip or the like, a relative speed is generated in the 2-row circumscribed gears 24, 25 and 26, 27 with a rotational speed respectively different, and a differential limiting effect is given by action in which viscous resistance of side surfaces, brought into contact with each other, tends to generate an equal rotational speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention is an external system that can be applied to vehicle drive devices such as work vehicles for lawn mowers and other vehicles without adding a special differential limiting device. Regarding gear type hydraulic motors.

[Prior Art] Conventionally, a vehicle drive device having a hydraulic circuit configuration shown in FIG. 7 has been generally used as a vehicle drive device for a work vehicle.

In the figure, 1 is an engine, and 2 is a variable discharge displacement partial pressure pump that is operated by the engine 1. When the variable discharge displacement partial pressure pump 2 is operated, 2
Hydraulic motors 4, 4° are operated, and left and right drive wheels 6, 6′ are driven via reduction gears 5, 5°. 7 is a charging pump that is operated by the engine 1 together with the variable discharge displacement partial pressure pump 2; 8 is a strainer for straining the oil sucked from the oil tank 9 by the operation of the charging pump 7; The oil sucked in by the operation of
It is then supplied to the low pressure side of the closed circuit 3. 12 is a charging relief valve for returning excess oil to the tank 13.

In the vehicle drive system having such a configuration, the two hydraulic motors 4, 4' operate not only as a drive torque generating device but also as a differential device for the left and right drive wheels 6, 6'. U.S. Pat. No. 33,558 is an illustrative prior art.
There is No. 86.

[Problem to be Solved by the Invention 1] By the way, the above vehicle drive system has no problems when driving on a normal road, but when driving on a snowy road where the driving wheels 6, 6' slip, one of the driving wheels 6 slips. If so, the other drive wheel 6° may lose its driving force.

Therefore, as a solution to such a case, as shown by the chain line in FIG.
4 between the drive wheels 6 and the power transmission shaft 15 at 6°.

Conventionally, the differential limiting device 14 has either been mechanical or uses a latch to completely stop the differential, or a friction torque generating device has been used to provide a slight differential limit. However, in either case, it is difficult to provide a differential limiting device as described above due to the layout with other components in the lower part of the vehicle body, and it is also not desirable from the cost standpoint.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an external gear type hydraulic motor having a differential limiting function that can be used as a drive torque generating device without adding a differential limiting device to a vehicle drive system.

[Means for Solving the Problems] In order to solve the above problems, the external gear meshing motor of the present invention has a pair of parallel gears passing through a motor housing consisting of a casing and a pair of side plates that close both side opening surfaces of the casing. Two pairs of external gears that are fitted to the first and second support shafts and mesh with each other are built into the motor housing, and one of the two external gears connected to the first support shaft is connected to the first and second support shafts. The external gear is fixed to a first support shaft, another external gear is loosely fitted to the first support shaft, and one of the two external gears connected to the second support shaft is an external gear that is loosely fitted to the first support shaft. An external gear that meshes with the gear is fixed to the second support shaft, another external gear is loosely fitted to the second support shaft, and the motor housing has pressurized oil that communicates with spaces on both front and rear sides of the external gear meshing part. It consists of a boat.

[Function] In the external gear type hydraulic motor of the present invention configured as described above, the output of the external gear in one of the two rows is transmitted to the first support shaft to which the external gear in that row is fixed, The output of the external gear in the other row is transmitted to a second support shaft to which the external gear in that row is fixed.

When such an external gear type hydraulic motor that rotates on two axes is applied to a vehicle drive system, if the drive wheels connected to a pair of support shafts through reduction gears are rotating at the same speed,
The two rows of external gears rotate at the same speed. If one of the pair of support shafts is idling due to slipping of the drive wheel, etc., the pair of parallel support shafts will have different rotational speeds, and a relative speed will occur between the two rows of external gears. At this time, the viscous resistance of the side surfaces of the two rows of external gears that were in contact with each other acts in a direction to make the two rows of external gears have the same rotational speed, giving a differential limiting effect. Therefore, by applying the external gear type hydraulic motor of the present invention to a vehicle drive system, a conventional differential limiting device becomes unnecessary.

[Example] An example of the external gear type hydraulic motor of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view, and FIG. 2 is a sectional view of the assembled state. In the figure, 20 is a casing with an oval outer circumference and a vertically continuous circular space 21 inside. A motor housing 23 is constituted by a pair of side plates 22 that close both side opening surfaces. Two pairs of external gears 2 are provided in the space 21 within the motor housing 23.
4.25, 26, and 27 are in contact with each other on their sides, and are built into the side plate 22, and the motor housing 23
It is supported by a pair of parallel support shafts 28 and 29 passing through the. One of the two external gears 24 and 26 is fixed to the first support shaft 28 with a key 30, and one of the two external gears 25 and 27 is fixed to the second support shaft 29. One external gear 27 on the opposite side is fixed with a key 31,
The remaining two external gears 25.26 are attached to each support shaft 28.2.
9 is rotatably fitted. The motor housing 23 is provided with pressure oil boats 32, 33 that communicate with both front and rear sides of the meshing portions of the two pairs of external gears 24, 25, 26, 27.

External gear type hydraulic motor 3 of the embodiment configured in this way
4 is the external gear 24 of one row of two rows due to the pressure oil contained in the pressure oil boat 32. The output of 25 is the external gear 24 of that row.
is transmitted to the first support shaft 28, to which the external gear 27 of the other row is fixed, and the output of the external gear 26, 27 of the other row is transmitted to the second support shaft 29, to which the external gear 27 of that row is fixed. Then, the pressure oil leaves the pressure oil boat 33.

The external gear type hydraulic motor 34 that rotates on two axes as described above is provided in the closed circuit 3 in order to be applied to the vehicle drive system shown in FIG. 29 is connected to the left and right drive wheels 6,6° via a reduction gear pja5,5°. To explain this arrangement with reference to FIG. 4, a power transmission gear 35 is provided at the outer end of the first support shaft 28 in the external gear type hydraulic motor 34, an idler gear 36 meshes with this, and an intermediate gear is connected to the idler gear 36. 37
A small-diameter intermediate gear 38, which is integral with the intermediate gear 37, meshes with an output gear 40 on the rotating shaft 39 of the drive wheel 6. Further, a power transmission gear 35° is provided at the outer end of the second support shaft 29, and an intermediate gear 37° meshes with this.
A small-diameter intermediate gear 38', which is integral with the drive wheel 6°, meshes with the output gear 40' on the rotation shaft 39 of the drive wheel 6°. Reducer 5 of the gear train from the power transmission gear 35 to the output gear 40
The reduction gears 5' from the power transmission gear 35° to the output gear 40' are set so that outputs in the same rotational direction can be obtained at the same reduction ratio.

A reduction gear 5,
If the drive wheels 6.6 connected through 5° rotate at the same speed, the two rows of external gears 24.25 and 26.27 of the externally geared hydraulic motor 34 rotate at the same speed. If one drive wheel 6 slips due to slipping or the like, the pair of parallel support shafts 2829 will have different rotational speeds, and a relative speed will occur between the two rows of external gears 24.25 and 26.27. do.

At this time, the viscous resistance of the contacting side surfaces of the two rows of external gears 24.25 and 26.27, that is, the Y plane in FIG. It acts in the direction that is intended to be achieved, giving a differential limiting effect. Therefore, the vehicle drive system to which the external gear type hydraulic motor 34 is applied does not need to be provided with a conventional differential limiting device.

In addition, if it is desired to increase the differential limiting effect of the external gear type hydraulic motor 34 of the above embodiment, as shown in FIG.
A recess 41 is provided concentrically around the penetrating portion of the support shafts 28 and 29 of the plane to form a step in the Y plane. By forming a step on the Y plane in this way, each of the external gears 24, 25, 26.
Hydraulic reaction force distribution (1) shown by arrows generated on the side of 27,
(I[) is left-right unbalanced, that is, the hydraulic reaction force distribution (II) generated on the side surface in contact with the side plate 22 is larger than the hydraulic reaction force distribution (I) generated on the side surface in contact with the external gears, and the two-row The external gears 24, 25 and 26, 27 press against each other in the direction. In this way, the two rows of external gears 24, 25, 26 and 27 experience not only viscous resistance in the Y plane but also frictional resistance proportional to the magnitude of the load. It acts strongly in the direction of trying to maintain the same rotational speed, and the differential limiting effect appears even more.

Even if the step on the Y plane described above is formed by simply providing a recess 41 on one side of the external gear 24.26 and one side of the external gear 25.27, the same differential restriction as described above can be achieved. Improvement in effectiveness can be seen.

In addition, as another means of increasing the differential limiting effect, the external gear 2
The specifications of 4.25.26.27 may be used for helical gears. A specific example is shown in FIG. That is, when operating in the rotational direction as shown in FIG. 6, the circumscribed helical gear 2
At 4° and 26°, the thrust force at the time of engagement acts in the direction in which they are pressed against each other, so that the same effect as in the case of providing a step on the Y plane shown in FIG. 5 can be obtained.

[Effects of the Inventionj] As can be seen from the above explanation, the external gear type hydraulic motor of the present invention is applied as a drive torque generating device to a vehicle drive device such as a work vehicle. Since the differential limiting effect appears at the time, there is no need to specially add a conventional differential limiting device to the vehicle drive system, and therefore there is no space interference with the layout with other components at the bottom of the vehicle body. Moreover, it only requires the space for one hydraulic motor instead of the conventional two. Further, since one external gear type hydraulic motor serves both as a drive torque generating device and a differential limiting device, costs are reduced.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an external gear type hydraulic motor of the present invention;
Figure 2 is a sectional view of the assembled state, Figure 3 is a diagram showing the hydraulic circuit configuration of a vehicle drive system for a work vehicle to which the external gear type hydraulic motor of the present invention is applied, and Figure 4 is the vehicle drive system. FIG. 5 is a sectional view showing another example of the external gear type hydraulic motor of the present invention, and FIG. 6 is a perspective view showing the arrangement of the external gear type hydraulic motor of the present invention and a drive wheel. FIG. 7 is a perspective view showing still another example of a gear type hydraulic motor, and is a diagram showing a hydraulic circuit configuration of a vehicle drive device of a conventional work vehicle. 20...Casing 22...Side plate 23...
- Motor housing 24, 25.26.27... External gear 28... First support shaft 29... Second support shaft 30, 31...
Key 32.33...Hydraulic boat No. 2 Diagram 3...Mo 7 Huffun 7 24.25, 26.27...Outer 4 teeth J0, 31...Mo...Outer tooth season゛Single 7-7 Figure 5

Claims (1)

[Claims] 1) A pair of parallel first and second support shafts passing through a motor housing consisting of a casing and a pair of side plates that close both side openings of the casing, and two mutually meshing support shafts. A pair of external gears is built into the motor housing, one of the two external gears connected to the first support shaft is fixed to the first support shaft, and the other external gear is fixed to the first support shaft. Of the two external gears that are loosely fitted to the shaft and are connected to the second support shaft, the external gear that meshes with the external gear that is loosely fitted to the first support shaft is fixed to the second support shaft, and An external gear type hydraulic motor, characterized in that an external gear is loosely fitted onto the second support shaft, and the motor housing is provided with a pressure oil port that communicates with spaces on both front and rear sides of the external gear meshing part.