JPH07334Y2 - Lubrication safety device for hydrostatic transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a lubrication safety device for a hydrostatic transmission in a vehicle.

(Prior Art) As a hydrostatic transmission used for a vehicle motive power transmission system, there is a hydrostatic transmission in which a variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit.

In this type of transmission, a casing is composed of a port block and a case attached to the port block, and a hydraulic pump and a hydraulic motor fluidly connected via the port block are housed in the casing, and a lubricating oil is used. Is stored so as to fill up.

(Problems to be Solved by the Invention) Conventionally, since the lubricating oil in the pump casing leaks from the gap of the casing, there is a drawback that the absolute amount of the lubricating oil varies.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object thereof is to always fill the casing with lubricating oil of a predetermined pressure or less.

(Means for Solving the Problems) As a means for solving the problems, the present invention comprises a casing 1 composed of a port block 2 and a case 3 attached thereto, and the casing 1 is provided with the port block 2 in between. In a hydrostatic transmission that accommodates a hydraulic pump 6 and a hydraulic motor 17 that are fluidly connected and stores the casing 1 so as to fill the lubricating oil, the port block 2 stores the lubricating oil in the casing 1. A safety valve 28 that opens when the pressure rises above a predetermined level is provided.

(Operation) Lubricating oil leaking from the hydraulic pump 6, the hydraulic motor 17, etc. is stored in the casing 1 in a full state. When the internal pressure in the casing 1 rises above a predetermined level, the poppet 30 of the safety valve 28 is pressed against the spring 35 to open, and a part of the lubricating oil escapes to the outside of the casing 1. Therefore, the casing 1 is always filled with the lubricating oil at a substantially constant pressure.

(Embodiment) The present invention will be described in detail below with reference to the illustrated embodiment.
In the figure, 1 is a casing, and a port block 2,
It is composed of a bowl-shaped case 3 attached to this, and the port block 2 is attached to the partition wall 5 of the mission case with bolts or the like while being positioned by the tubular body 4. 6
Is a hydraulic pump, a cylinder block 7, a plurality of pistons 8 provided in the cylinder block 7 in the circumferential direction,
The swash plate 9 is disposed so as to face the piston 8, and the piston 8 is slidable with respect to the swash plate 9 via a piston shoe 10. The cylinder block 7 is splined to the input shaft 11, and the input shaft 11 has a needle bearing 12 and a ball bearing 13
It is rotatably supported by the port block 2 and the case 3 via. The input shaft 11 has an input unit 14 at one end and an output unit 15 at the other end. The swash plate 9 is supported by the pair of swash plate shafts 16 located on the axis orthogonal to the input shaft 11 so that the angle can be changed with respect to the case 3. 17 is a hydraulic motor,
Cylinder block 19 splined to output shaft 18
And a plurality of pistons 20 provided in the cylinder block 19 in the circumferential direction and a swash plate 21 that is fixed to the case 3 so as to face the piston 20.
It is slidable on the swash plate 21 via 22. The output shaft 18 is rotatably supported by the port block 2 and the case 3 via a needle bearing 23 and a ball bearing 24.

A port (not shown) that fluidly connects the hydraulic port 6 and the hydraulic motor 17 is formed in the port block 2, and the charge port 25, the charge filter 26, the charge check valve, and the charge safety valve 27 are formed. Etc. are provided,
Further, a safety valve 28 for keeping the lubricating oil filling the casing 1 at a predetermined pressure or less is provided.

As shown in FIG. 2, the safety valve 28 has a poppet 30 with a flange 29, and the poppet 30 is slidably inserted from the large diameter hole 31 side formed in the port block 2 to the small diameter hole 32 side. There is. An oil passage 33 is formed in a T shape in the poppet 30,
The poppet 30 is biased in the closing direction by a spring 35 interposed between the spring receiver 34 and the flange portion 29. The spring pressure of the spring 35 is set to a predetermined low pressure necessary for storing the lubricating oil, and when the pressure exceeds the predetermined pressure, the poppet 30 is pushed and the safety valve 29 is opened. The spring receiver 34 has a ring shape and is locked by a retaining ring 36 fitted to the opening end side of the large diameter hole 31. 37, 38, 39 are oil seals.

In the above structure, when the swash plate 9 of the hydraulic pump 6 is tilted around the swash plate shaft 16 while the input shaft 11 is rotated, the hydraulic pump 6 discharges an amount of oil according to the swash plate angle. Then, the discharged oil circulates with the hydraulic motor 17 via the port of the port block 2 and rotates the output shaft 18 via the cylinder block 19 of the hydraulic motor 17.

The oil leaked from the hydraulic pump 6 and the hydraulic motor 17 is stored in the casing 1 in a filled state so as to lubricate them. When the pressure in the casing 1 rises, the poppet 30 of the safety valve 28 senses the rise in pressure and slides in the direction of arrow A against the spring 35, so that the safety valve 28 opens as shown in FIG. Lubricating oil in 1 passes through the small diameter hole 32, the oil passage 33 of the poppet 30 and the large diameter hole 31 and is released to the outside, that is, inside the mission case. Therefore, the casing 1 is always filled with the lubricating oil of a predetermined pressure or less, and the hydraulic pump 6, the hydraulic motor 17, etc. can be lubricated without excess or deficiency.

According to the present invention, since the safety valve 28 that opens when the pressure of the lubricating oil in the casing rises above a predetermined level is provided,
Lubricating oil of a predetermined pressure or less can be always stored in the casing 1 in a full state. Further, since the safety valve 28 is provided in the port block 2, it can be processed and incorporated in the same manner as other valves.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is an overall sectional view,
FIG. 2 is an enlarged sectional view of the safety valve, and FIG. 3 is an operation explanatory view of the safety valve. 1 ... Casing, 2 ... Port block, 6 ... Hydraulic pump, 11 ... Input shaft, 17 ... Hydraulic motor, 18 ... Output shaft, 28 ... Safety valve, 30 ... Poppet.

Claims (1)

[Scope of utility model registration request] 1. A casing 1 is composed of a port block 2 and a case 3 attached thereto, and a hydraulic pump 6 and a hydraulic motor 17 are fluidly connected to the casing 1 via the port block 2. And the casing 1
In a hydrostatic transmission in which the lubricating oil is stored so as to be filled therein, the port block 2 is provided with a safety valve 28 that opens when the pressure of the lubricating oil in the casing 1 rises above a predetermined level. Lubrication safety device for hydraulic transmission.