JPH068307Y2 - Boost pump in swash plate pump - Google Patents

Description

TECHNICAL FIELD The present invention relates to the structure of a boost pump for a swash plate pump, particularly a tandem swash plate pump.

2. Description of the Related Art FIG. 2 shows the outer shape of a tandem swash plate pump. The tandem swash plate pump comprises a first swash plate pump 1 and a second swash plate pump 2 which are connected to each other by respective drive shafts 3 and 4.

The first swash plate pump 1 includes a cylinder block 6 fixed to a drive shaft 3, a plurality of cylinder parts 7 are formed in the cylinder block 6, and a piston 8 is fitted and inserted into these cylinder parts 7. There is. The spherical portion 9 at one end of the piston 8 is rotatably connected to the shoe 10. Shoe 10
The flat portion of the above-mentioned slides on the swash plate surface 11 in response to the rotation of the cylinder block 6. A shoe retainer 12 is provided on the shoe 10 to hold the shoe 10 in sliding contact. The rear surface of the cylinder block 6 is in sliding contact with the valve plate 14 held by the end cap 13.

The second swash plate pump 2 has the same structure as the first swash plate pump 1 described above.

Then, the rotational force input by the drive shaft 3 of the first swash plate pump 1 causes the cylinder block 6 to rotate. The rotation of the cylinder block 6 causes the piston 8 to slide on the swash plate surface 11 via the shoe 10 so that the piston 8 reciprocates in the cylinder portion 7, thereby performing suction and discharge strokes to form a hydraulic pump. To do. The same applies to the second swash plate pump 2.

In many tandem swash plate pumps, a boost pump is built into the pump body to improve self-priming performance.

This is for the following reason.

(1) If the pump is used at a rotation speed higher than the self-priming performance, cavitation may occur in the pump, noise and vibration may increase, and the pump itself may be damaged.

(2) The main factor limiting the self-priming performance (generation of cavitation) of the pump is the swash plate pump, when the hydraulic oil flows from the valve plate port to the cylinder block port, when it flows in (suction), and the pump mechanism. In addition, in the cylinder block port portion, a large pressure drop is caused, and if the pressure of the hydraulic oil at this time becomes equal to or lower than the air separation pressure of the hydraulic oil, bubbles are generated from the hydraulic oil to cause cavitation.

(3) Therefore, by installing a boost pump, the suction pressure is boosted by the boost pump, and if this is introduced into the end cap port → valve plate port → cylinder block port → cylinder port, the cylinder block port section The self-priming performance of the pump is improved due to the boost pressure boosting, even if the pressure loss at the point becomes large.

For this reason, the tandem swash plate pump is provided with the boost pump 5, that is, the pump chamber 15 is formed between the end caps 13 and 13 'of the first and second swash plate pumps 1 and 2. An impeller 16 is housed in the chamber 15. The impeller 16 is a coupling 1 that connects the drive shafts 3 and 4.
It is attached to 7.

The end cap 13 'is provided with a suction port 18 leading to the pump chamber 15, and the discharge port 19 is the first
Valve plates 14, 14 'of the second swash plate pumps 1, 2
Leading to the suction port.

Then, when the first and second swash plate pumps 1 and 2 are driven, the impeller 16 rotates and the hydraulic oil flowing in from the suction port 18 is increased in pressure and discharged from the discharge port 19 to the first and second swash plate pumps 1 and 2. 2 into the suction ports of the valve plates 14, 14 '.

However, although the conventional structure has only one suction port 18, two end caps, that is, the end caps 13 and 13 'of the first and second swash plate pumps 1 and 2 are required. In addition, the number of parts for connecting these end caps 13 and 13 'has increased, resulting in increased cost. Also, the fact that two end caps 13 and 13' are required means that the parts are combined together. A surface is required, and there is a lot of concern about oil leakage from the mating surface due to defective processing.

Moreover, since the distance from the discharge port 19 of the boost pump 5 to the suction ports of the valve plates 14 and 14 'is long and the shape is complicated, the pressure drop of the hydraulic oil is large.

The present invention has been made in view of the above circumstances.
・ The end cap of the second swash plate pump is composed of one block-shaped casing, and the mating surface that occurs when the conventional casing is composed of two end caps is eliminated, and oil leakage due to processing defects etc. is eliminated. , It is possible to reduce the cost by reducing the number of pump parts and to shorten the passage connecting the discharge side of the impeller and the suction port of the valve plate of the first and second swash plate pumps to reduce the pressure loss, Furthermore, the speed of the booster pump impeller can be freely set, such as increasing the speed without being restricted by the rotation of the drive shaft of the swash plate pump. The discharge liquid of the boost pump can be set as an efficient boost pump by supplying the entire amount of the discharge liquid to the swash plate pump through the impeller. It is an object that can.

Means and Actions for Solving Problems In order to achieve the above-mentioned object, the present invention configures the end caps of the first and second swash plate pumps 30 and 40 with one block-shaped casing 20. The casing 20 is provided with a pump chamber 21, and the pump chamber 21 is provided with an impeller 39 having a rotation center axis perpendicular to the axes of the drive shafts of the first and second swash plate pumps 30 and 40. The impeller 39 is connected to the casing 20 via a power transmission means using gears, and the suction port 42 facing the suction side of the impeller 39 and the discharge side of the impeller 39 are connected to the casing 20 by the first and second swash plate pumps 30, 40 valve plates 4
Passage 4 communicating with suction ports 49, 50 of 7, 48
3, 44 and the discharge port 5 of the valve plates 47, 48
The discharge ports 45 and 46 communicating with the nozzles 1 and 52 are provided.

Then, when the first and second swash plate pumps 30 and 40 are rotationally driven, the impeller 39 is rotated through the power transmission means to increase the pressure of the hydraulic oil sucked from the suction port 42 and discharge it.
It is configured to supply the suction ports 49, 50 of the valve plates 47, 48 of the first and second swash plate pumps 30, 40 via 3, 44.

Embodiment An embodiment of the present invention will be described below with reference to FIG. Reference numeral 20 in the drawing denotes a housing that also serves as an end cap of the first and second swash plate pumps 30 and 40. The casing 20 is provided with a pump chamber 21 and a drive unit accommodating chamber 22, and the housing 20 is provided with bearing holes 23 and 24 communicating with the drive unit accommodating chamber 22. The drive shaft 25 of the first swash plate pump 30 is supported in the one bearing hole 23 via a bearing 26, and the drive shaft 27 of the second swash plate pump 40 is supported in the other bearing hole 24. It is supported via a bearing 28, and a coupling 32 is fitted to spline portions 29 and 31 of both drive shafts 25 and 27. The coupling 32 is fixed to the drive shafts 25 and 27 by a holder 33 and bolts 34. Has been done.

A bevel gear 34 is fixed to the coupling 32.

Inside the pump chamber 21, inside the outer support seat portions 35, 36,
The outer bushes 37 and 38 are fitted, and the impeller 39 is rotatably held by the outer bushes 37 and 38. A bevel gear 41 is formed on the inner peripheral portion of the impeller 39, and the bevel gear 41 meshes with the bevel gear 34.

The casing 20 has a suction port 42 and first and second
Passages 43 and 44 and the first and second discharge ports 45 and 46
And the suction port 42 is provided on the impeller 39.
Facing the suction port 39a of the first and second passages 4
The inlet side of 3, 44 communicates with the discharge ports 45, 46 of the impeller 39, and the outlet side of the first and second passages 43, 44 has the valve plate 4 of the first and second swash plate pumps 30, 40.
7 and 48 are connected to suction ports 49 and 50.

Further, the first and second discharge ports 45, 46 communicate with the discharge ports 51, 52 of the valve plates 47, 48.

Next, the operation will be described.

When the first and second swash plate pumps 30 and 40 are rotationally driven, the impeller 39 is rotated by the rotation of the drive shafts 25 and 27, and the hydraulic oil sucked from the suction port 42 is pressurized to increase the pressure of the impeller 3.
It is discharged from the discharge ports 45 and 46 of 9 and is supplied to the suction ports 49 and 50 of the valve plates 47 and 48 of the first and second swash plate pumps 30 and 40 through the passages 43 and 44.

Valve plate 4 of the first and second swash plate pumps 30 and 40
The hydraulic oil discharged from the discharge ports 51 and 52 of 7, 48 is discharged to the discharge ports 45 and 46.

Further, in the above-described operation, the rotation of the impeller 47 is not restricted by the rotation of the drive shaft 25 and can be arbitrarily set by changing the gear ratio of the power transmission means connecting the drive shaft 25 and the impeller 47. Further, the entire amount of oil discharged from the impeller 47 is discharged through the impeller 47.

Effect of the Invention As described in detail above, in the boosting pump of the tandem swash plate pump according to the present invention, the end caps of the first and second swash plate pumps 30 and 40 are constituted by one block-shaped casing 20. Then, the casing 20 is provided with a pump chamber 21, and the pump chamber 21 is provided with an impeller 39 having a center axis of rotation in a direction perpendicular to the axes of the drive shafts of the first and second swash plate pumps 30 and 40. The drive shaft and the impeller 39 are connected via a power transmission means using a gear, and a suction port 42 facing the suction side of the impeller 39 and a discharge side of the impeller 39 are connected to the casing 20 at the first and second positions.
Valve plates 47, 4 of the second swash plate pumps 30, 40
Passages 43 and 44 communicating with the suction ports 49 and 50 of FIG.
And the discharge ports 45 and 46 communicating with the discharge ports 51 and 52 of the valve plates 47 and 48, respectively.

Therefore, since the end caps of the first and second swash plate pumps 30 and 40 are configured by one block-shaped casing 20, there is no mating surface that occurs when the casing is configured by two conventional end caps, and machining is performed. Oil leakage due to defects and the like will be eliminated, and the number of pump parts will be reduced, so that the cost can be reduced.

Further, since the impeller 39 is provided with the rotation center axis in the direction perpendicular to the axes of the drive shafts 25 and 27, the discharge side of the impeller 39 and the valve plates 47 and 48 of the first and second swash plate pumps 30 and 40 are provided. The passages 43 and 44 connecting the suction ports 49 and 50 can be shortened, and the pressure loss can be reduced.

Further, according to the present invention, the impeller 39 is provided so as to have a rotation center axis in a direction perpendicular to the axis of the drive shaft, and the drive shaft and the impeller 39 are connected via a power transmission means using gears. As a result, the rotational speed of the booster pump impeller can be increased freely without being restricted by the rotation of the drive shaft of the swash plate pump. Can be set according to the above, and the discharge liquid of the boosting pump can be an efficient boosting pump by supplying the entire amount thereof to the swash plate pump through the impeller.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of the present invention, FIG. 2 is a front view of a tandem swash plate pump having a conventional boost pump, and FIG. 3 is a sectional view taken along line III-III in FIG. is there. 20 is a casing, 25 and 27 are drive shafts, and 39 is an impeller.

Claims (1)

[Scope of utility model registration request] 1. The end caps of the first and second swash plate pumps 30 and 40 are constituted by a single block-shaped casing 20, and a pump chamber 21 is provided in the casing 20, and the first and second pump chambers 21 are provided in the pump chamber 21, respectively. An impeller 39 having a rotation center axis perpendicular to the axis of the drive shaft of the second swash plate pumps 30 and 40 is provided, and the drive shaft and the impeller 39 are connected via a power transmission means using gears, Casing 20
The first and second discharge sides facing the suction side of the impeller 39 are
The passages 43 and 44 communicating with the suction ports 49 and 50 of the valve plates 47 and 48 of the swash plate pumps 30 and 40 and the discharge ports 45 and 46 that communicate with the discharge ports 51 and 52 of the valve plates 47 and 48. A boosting pump for a swash plate pump.