JPH0533171B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a power transmission device used for a riding type vehicle such as a three-wheel or four-wheel buggy. The present invention relates to a hydraulic circuit of a continuously variable power transmission device that changes speed.

(Prior Art and its Problems) The applicant has developed a continuously variable transmission power transmission device suitable for this type of buggy vehicle, etc., and has already filed an application for the same (Japanese Patent Application No. 202535/1983).

In this prior art, lubricating oil for the engine and hydraulic oil for the hydrostatic power transmission mechanism are shared, but only one hydraulic pump is used to supply pressure oil to both.
If multiple units are used, the following problems can be expected.

In other words, if the hydraulic oil becomes hot due to continued operation and its viscosity decreases, the volumetric efficiency of the hydraulic pump will decrease, and the amount of leakage in the hydrostatic power transmission mechanism that receives the hydraulic oil supply will increase. As a result, most of the pressure oil from the hydraulic pump flows into the hydrostatic power transmission mechanism, and there is a possibility that the amount of lubricating oil supplied to the engine side will be insufficient.

Further, if two hydraulic pumps are provided and oil is supplied to both separately, the structure becomes complicated and costs increase.

(Object of the Invention) The present invention provides the ability to supply lubricant to the engine even when a single hydraulic pump is used for both the supply of lubricant to the engine and the supply of hydraulic oil to the hydrostatic power transmission mechanism. The purpose of this project is to provide a hydraulic circuit for continuously variable transmission power transmission (HST) that can maintain the following conditions.

(Structure of the Invention) (1) Technical Means The present invention provides a variable hydraulic pump that is driven by the output shaft of an engine and can freely adjust the discharge amount, and a driving force that is applied to the axle by receiving the hydraulic pressure from the variable hydraulic pump. In a hydraulic circuit of a continuously variable power transmission device having a hydrostatic power transmission mechanism unit combined with a hydraulic motor to be converted, oil stored in an oil pan is supplied to both a lubricating unit of the engine and the variable hydraulic pump. A continuously variable transmission characterized in that a single hydraulic pump capable of supplying oil is provided, and this hydraulic pump serves both as an engine lubricant supply pump and a hydraulic oil supply pump to a hydrostatic power transmission mechanism section. This is the hydraulic circuit of the power transmission device.

(2) Function A single hydraulic pump supplies pressure oil to both the engine and the hydrostatic power transmission mechanism (HST) while maintaining the required amount of lubricating oil to the engine.

(Embodiment) In FIG. 1, which shows a case where the present invention is applied to, for example, a four-wheeled buggy vehicle, an engine 20 is arranged with its crankshaft (output shaft) oriented vertically.
This engine 20 is provided with a transaxle 22 that is integrally connected, and transmits driving force from the transaxle 22 to rear tires 24, and a part of the engine power is transmitted from the engine 20 via a V-belt 14, for example, for lawn mowing. The information is transmitted to a working machine such as machine 18.

As shown in FIG. 2, when the engine 20 and transaxle 22 are viewed from the direction of the arrow in FIG. On the output shaft portion 28 of the crankshaft 26, a variable hydraulic pump 30, which will be described in detail later, is surrounded by a pump cover 34 that is part of a housing 32. A pulley 35 is fixed to the lower end of the output shaft portion 28, and power is taken out to the lawn mower 18 (FIG. 1) via the V-belt 14.

The housing 32 is composed of a pump cover 34, a lower case 36, and an axle housing 38, and these three members are integrally connected to each other. That is, the lower case 36 is fixed to the bottom surface of the crank case 20a of the engine 20 with bolts (not shown), the pump cover 34 is fixed to the lower case 36 with a plurality of bolts 34a, and the axle housing 38 is similarly fixed to the crank case 20a with a plurality of bolts 38a. It is fixed to the side surfaces of the case 20a and the lower case 36.

Inside the axle housing 38, a crescent-type hydraulic motor 40, which is part of a drive axle device to be described in detail later, is built in, and this crescent-type hydraulic motor 40 rotationally drives a split axle 41 that constitutes a drive axle. It's getting old. At the end of the split axle 41, a rear tire 24 with low pressure, large diameter, and high cushioning function is provided. Further, the crescent type hydraulic motor 40 and the variable hydraulic pump 30 are communicated with each other through hydraulic oil passages 42 and 44. These hydraulic oil passages 42 and 44 are connected to the lower case 36.
It is formed within the wall thickness of the hydraulic oil passages 42, 4.
4 lower case 36 and axle housing 38
An inner pipe 43 is inserted into the joint portion.

The above-mentioned HST section is composed of the variable hydraulic pump 30, crescent type hydraulic motor 40, etc.
The structure of this HST section will be explained in FIG.

In FIG. 3, the variable hydraulic pump 30 includes a cylinder block 46, a ball piston 47, and a cam ring 4.
The output shaft portion 28 of the crankshaft 26 is fixed to the center of the cylinder block 46 by, for example, press fitting. Note that in FIG. 3, the output shaft portion 28 extends in a direction perpendicular to the paper surface.

Oil chambers 46a are formed on the outer periphery of the cylinder block 46 at equal intervals in the circumferential direction and open radially outward. Each oil chamber 46a
A ball piston 47 is reciprocatably fitted into the.

A cam ring 48 is provided radially outward of the ball piston 47, and the cam ring 48 is connected to the pump cover 34 and the lower case 36 (Fig. 2).
It is rotatably held around a pin 47a that fits into the. By rotating the cylinder block 46 while each ball piston 47 is in sliding contact with the cam surface 48a of the cam ring 48, the ball piston 47 reciprocates within the oil chamber 46a, and the piping 30a
The hydraulic oil sucked in from the pipe 30b is discharged from the pipe 30b.

The pipe 30a is connected to the oil chamber 46a through an arcuate port 46b and a hole 46c, and the pipe 30b is connected to the oil chamber 46a through an arcuate port 46d and a hole 46e.
It is connected to a. A recess 48b is formed at the right end of the cam ring 48, and a discharge amount adjusting shaft 49 is fitted into this recess 48b. Therefore, by moving the discharge amount adjusting shaft 49 in the direction of arrow A in the figure, the entire cam ring 48 is rotated around the pin 47a, and the reciprocating amount of the ball piston 47, that is, the discharge of the variable hydraulic pump 30 is adjusted. The amount is now being adjusted.

The pipe 30b is connected to a hydraulic oil passage 44 (FIG. 2), from which pressure oil is supplied to the crescent-type hydraulic motor 40, and from the hydraulic oil passage 42 connected to the crescent-type hydraulic motor 40 to the piping 3.
This structure allows hydraulic oil to flow back to Oa. Check valves 44a, 42a are provided between the piping 51 sucking up hydraulic oil from the oil pan 50 of the engine 20 and the hydraulic oil passages 42, 44.

The crescent type hydraulic motor 40 has an inner gear 52 connected to a split axle 41 (FIG. 2), an outer gear 53 that meshes with the outer teeth 52a of the inner gear 52, and an oil chamber between the inner teeth 53a and the outer teeth 52a. The inner gear 52 and the outer gear 53 are configured with a substantially crescent-shaped partition member 54, and the inner gear 52 and the outer gear 53 are
This is a well-known structure that rotates in the direction. Note that the crescent type hydraulic motor 40 itself has hydraulic oil passages 42 and 4.
By switching the flow direction of the hydraulic oil in step 4, forward and reverse rotation is possible, and reverse switching is also possible.

Next, the hydraulic circuit which is the gist of the present invention will be explained.
A pipe 82 is branched and connected to the pipe 51 , and the other end of the pipe 82 extends to a lubricating section of the engine 20 . Further, a check valve 83 is interposed in a portion of the pipe 51 near the oil pan 50.

In the middle of the pipe 82, a pipe 85 for flowing pressure oil from a shared hydraulic pump 84 etc. is branched and connected.
The suction side end of is connected to the oil pan 50.

A sequence valve 88 is interposed between the connection points 86 and 87 of the pipe 82, and the sequence valve 88 for charging the HST section is connected to the PH
The valve is adjusted to close at kg/ ^cm2 .

Further, a pipe 89 is connected to the connection point 86, and the other end of the pipe 89 drains into the oil pan 50. A sequence valve 90 for engine lubrication is interposed in the middle of the pipe 89. The closing pressure of this sequence valve 90 is adjusted to PEKg/cm ² which is higher than PHKg/cm ² . Therefore,
Summarizing each pressure regulation pressure, PE>PH...(1).

Furthermore, a throttle 91 is interposed in a portion of the pipe 82 closer to the engine than the connection point 86.

Next, a drive axle device provided around the split axle 41 will be described with reference to FIG. In FIG. 4, the crescent-type hydraulic motor 40, a planetary gear reducer 55, a differential gear 56, a brake 57, etc. are provided around the right split axle 41, and each of these mechanisms is connected to the axle. It is surrounded by a housing 38.

Partition member 54 of crescent type hydraulic motor 40
is fixed to a side cover 58, which is a part of the axle housing 38, with bolts 54a. Further, the partition member 54 is continuous with a motor housing 59 which is also connected to the axle housing 38.

Inner gear 5 of crescent type hydraulic motor 40
2 is spline-fitted to a cylindrical output shaft 60 that fits radially outwardly of the split axle 41 at a distance, and a sun gear 61 is formed at the right end of the cylindrical output shaft 60 in the figure. A planetary gear 62 of a planetary gear reducer 55 is meshed with the sun gear 61 . On the outside of this planetary gear 62 is a ring gear 6 that meshes with the planetary gear 62 and is fixed to the axle housing 38.
3, and a carrier 64 holding the planetary gear 62 is spline-fitted to a cylindrical shaft 65.

A sun gear 66 is formed at the right end of the cylindrical shaft 65, and a planetary gear 67 meshes with the sun gear 66. A ring gear 68 fixed to the axle housing 38 is provided outside the planetary gear 67, and the planetary gear 67 is held by a carrier 69. The carrier 69 and the carrier 64 are separate bodies, and a lubricating oil passage 69a is formed in the sliding surfaces thereof.

The carrier 69 is the differential gear 56
It is continuous with the differential cage 70, and the differential cage 7
0 has a built-in center pin 71, pinion gear 72, and side gear 73. The left and right side gears 73 are spline-fitted to the left and right split axles 41.

Therefore, the driving force from the crescent type hydraulic motor 40 is reduced by the planetary gear reducer 55 and then transferred to the two split axles 41 by the differential gear 56.
It is now being transmitted to

A brake disc 74 is spline-fitted to the left end of the cylindrical output shaft 60, and a brake pad 75 is provided to the right end of the brake disc 74. A push rod 77 having a brake pad 76 is provided on the left side of the brake disc 74, and by pushing the push rod 77 in the direction of arrow C,
A braking force is generated to stop the rotation of the split axle 41.

The ends of the left and right split axles 41 are pivotally supported by the axle housing 38 via bearings 78, and an annular rubber insulator 80 is fitted into the annular groove 79 of the axle housing 38. The insulator 80 is held by a side frame 81 that is a part of the vehicle body, and the axle housing 38 is floatingly supported with respect to the side frame 81 by the elasticity of the insulator 80.

Next, the effect will be explained. In the above transaxle, as shown in FIG.
The pressure oil discharged from is divided at the connection point 86,
Pressure oil flows left and right through the piping 82 to the piping 51, and flows to the right in FIG.

The shared hydraulic pump 84, which is used both to supply hydraulic oil to the variable hydraulic pump 30 and to supply lubricating oil to the lubricating section of the engine 20, has a sufficient discharge amount under normal conditions. In this state, the sequence valve 88
Pressure oil whose pressure is regulated to PEKg/cm ² flows into the variable hydraulic pump 30 from the piping 51, while the engine 20
The orifice 91 is connected from the connection point 86 to the engine side.
Through the lubricating oil is supplied at a pressure in the range of PHKg/cm ² to PEKg/cm ² .

Here, due to long-term continuous operation, the oil temperature rises, the discharge amount of the common hydraulic pump 84 decreases, and the amount of leakage from the variable hydraulic pump 30 and the crescent type hydraulic motor 40 increases, and the common hydraulic pump 84 If the discharge amount of the shared hydraulic pump 84 becomes relatively insufficient, most of the discharge amount from the shared hydraulic pump 84 will flow to the variable hydraulic pump 30 side, and the lubricating oil supplied to the engine 20 side will be reduced. However, in the hydraulic circuit according to the present invention, as follows,
Solve this problem.

That is, when the discharge amount from the shared hydraulic pump 84 becomes insufficient as described above, the pressure within the pipe 82 decreases and the sequence valve 88 closes. Since the sequence valve 90 is closed before the sequence valve 88 is closed, all of the pressure oil from the shared hydraulic pump 84 is supplied from the pipe 89 to the lubricating section of the engine 20 with priority. Therefore, even if the discharge amount of the shared hydraulic pump 84 is insufficient, most of the pressure oil from the shared hydraulic pump 84 will flow to the variable hydraulic pump 30 side, resulting in a shortage of lubricating oil for the engine 20. This will be prevented.

Note that in this state where the sequence valve 88 is closed, the variable hydraulic pump 30 has 51
The check valve 83 is pushed aside by the suction pressure of the variable hydraulic pump 30, and the oil stored in the oil pan 50 is sucked in.

As shown in FIG. 2, the axle housing 38 that pivotally supports the split axle 41 is attached to the lower case
Since the pump cover 34 surrounding the variable hydraulic pump 30 is connected to the crankcase 20a and further connected to the lower case 36, even when the axle housing 38 is floatingly supported by the insulator 80 shown in FIG. The variable hydraulic pump 30 moves integrally with the axle housing 38. Therefore, the power of the engine 20 is converted into hydraulic pressure by the variable hydraulic pump 30, and this hydraulic pressure is converted into driving force by the crescent type hydraulic motor 40 in FIG. 4 through the hydraulic oil passages 42 and 44. . The driving force from the crescent-type hydraulic motor 40 is reduced by a planetary gear reducer 55 and transmitted to the left and right split axles 41 from a differential gear 56 .

These drive axle devices such as the crescent type hydraulic motor 40, the planetary gear reducer 55, the differential gear 56, and the brake 57 are housed as a unit inside the axle housing 38.
The outer shape of the axle housing 38 is compact.

Further, as shown in FIG. 3, a variable hydraulic pump 30
Since the hydraulic oil flowing between the hydraulic oil pump 30 and the crescent type hydraulic motor 40 shares the lubricating oil stored in the oil pan 50 of the engine 20, the frictional heat generated in the variable hydraulic pump 30 and the crescent type hydraulic motor 40 is Since the oil pan 50 having a large heat dissipation capacity is used for cooling, there is no fear that the hydraulic oil of the variable hydraulic pump 30 and the crescent type hydraulic motor 40 will overheat.

Note that the viscosity required for the variable hydraulic pump 30 and the crescent-type hydraulic motor 40 is higher than that of the lubricating oil for the engine 20, and so-called multigrade oil having a wide viscosity range is used as the lubricating oil for the engine 20. lubricating oil for the engine 20, variable hydraulic pump 30, and crescent type hydraulic motor 40.
Also serves as hydraulic oil.

(Effects of the Invention) As explained above, the hydraulic circuit of the continuously variable transmission power transmission device according to the present invention includes, as shown in FIG. And this variable hydraulic pump 3
The oil is stored in an oil pan 50 in a hydraulic circuit of a continuously variable transmission power transmission device that has a hydrostatic power transmission mechanism combined with a hydraulic motor 40 that receives hydraulic pressure from zero and converts it into driving force for the axle. One common hydraulic pump 84 is provided that can supply oil to both the lubricating section of the engine 20 and the variable hydraulic pump 30, and this common hydraulic pump 84 serves as an engine lubricating oil supply pump and a hydrostatic power transmission. Since the hydraulic oil supply pump for the mechanism section is shared, one common hydraulic pump 84 can supply hydraulic oil and lubricating oil to both the variable hydraulic pump 30 and the lubricating section of the engine 20. , the structure becomes simpler.

In particular, the shared hydraulic pump 84 is replaced with the engine 2 in response to the insufficient discharge amount of the hydraulic pump 84.
When forming part of a sequence circuit having two relief valves 89 and 90 with different set pressures so as to preferentially distribute lubricating oil of 0.0, the following effects can be achieved.

The discharge amount from the shared hydraulic pump 84 is insufficient,
When the oil pressure in the pipe 82 decreases, the opening pressure of the sequence valve 88 becomes less than PEKg/cm ² and closes the sequence valve 88. On the other hand, before the sequence valve 88 closes, the sequence valve 9
Since the valve 0 is already closed, all of the pressure oil can be supplied to the lubricating section of the engine 20 with priority at the connection point 86.

Therefore, even if the discharge amount of the shared hydraulic pump 84 is insufficient, most of the pressure oil from the shared hydraulic pump 84 will flow to the variable hydraulic pump 30 side, resulting in a shortage of lubricating oil for the engine 20. This can be prevented.

(Another embodiment) (1) The continuously variable transmission power transmission device of the present invention is not limited to the embodiment shown in FIG.
8 is not fixed to the lower case 36 and crankcase 20a with bolts 38a, but the axle housing 38 and lower case 36 are separated,
If the hydraulic oil passages 42 and 44 between the two are connected with a flexible hydraulic hose, the insulator 8
0 (FIG. 4), the mass of the axle housing 38 that is floatingly supported, that is, the unsprung mass, is reduced, and vibrations of the engine 20 are also isolated.

[Brief explanation of the drawing]

Fig. 1 is a rear perspective view of a four-wheel buggy vehicle adopting the present invention, Fig. 2 is a partial cutaway view taken in the direction of the arrow in Fig. 1 showing the engine and transaxle mounted on the buggy car, and Fig. 3 is a variable A schematic structural diagram showing a hydraulic pump and a crescent-type hydraulic motor, and FIG. 4 is a partial cross-sectional view taken at - in FIG. 2. 20...Engine, 2
2... Transaxle, 30... Variable hydraulic pump, 32... Housing, 34... Pump cover, 36... Lower case, 38... Axle housing, 40... Crescent type hydraulic motor, 4
1...Split axle, 50...Oil pan, 55...
Planetary gear reducer, 82... Piping, 84... Common hydraulic pump, 88, 90... Sequence valve.

Claims (1)

[Scope of Claims] 1. A variable hydraulic pump that is driven by the output shaft of an engine and can freely adjust the discharge amount, and a hydraulic motor that receives hydraulic pressure from the variable hydraulic pump and converts it into driving force for the axle. In a hydraulic circuit of a continuously variable transmission power transmission device having a hydrostatic power transmission mechanism section, one hydraulic circuit is configured to supply oil stored in an oil pan to both a lubricating section of the engine and the variable hydraulic pump. A hydraulic circuit for a continuously variable power transmission device, characterized in that a hydraulic pump is provided, and the hydraulic pump serves as both an engine lubricating oil supply pump and a hydraulic oil supply pump to a hydrostatic power transmission mechanism. 2. The shared hydraulic pump is part of a sequence circuit that has two relief valves with different set pressures to prioritize and distribute lubricating oil for the engine in response to the insufficient discharge volume of the hydraulic pump. A hydraulic circuit for a continuously variable transmission power transmission device according to claim 1.