JPS61237888A - Swash-plate plunger pump - Google Patents

Abstract

PURPOSE:To easily hold the neutral point of a swash-plate pump by constituting the captioned pump so that a cylinder block and a valve plate turn in integration only in the direction crossing nearly at right angles to the direction of tilt of the swash plate. CONSTITUTION:A cylinder block 11 is joined with an input shaft 12 through a spline, and said cylinder block 11 is constituted so as to permit the chattering for the input shaft 12. On the shoulder surface of a valve plate 17 which contacts with the cylinder block 11, an arcuate projecting part 18 is formed in the radial direction, and the valve plate 17 and the cylinder block 11 are supported so as to turn only in the direction crossing nearly at right angles to the direction of tilt of the swash plate 15. therefore, when the tilt angle of the swash plate 15 is set closely to zero, the cylinder block 11 and the valve plate 17 are turned a little by the pressure balance, and the return to the neutral point is automatically carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a swash plate plunger pump used in hydrostatic transmissions, engines (hereinafter referred to as H5T), and the like.

(Prior Art) The H5T forms a closed circuit with a variable displacement swash plate plunger pump and a constant displacement swash plate plunger motor, and controls the operating speed of the plunger motor according to the discharge amount of the plunger pump.

In this case, the operating lever is operated to change the tilting direction of the swash plate plunger pump to move the vehicle forward.
The vehicle is moved backward and its tilt angle is set to zero to stop the vehicle. Therefore, the stopping characteristics when the operating lever is held at the neutral position greatly affect the safety of the vehicle.

At this time, if there is only one point on the operating lever to stop the vehicle, the point may be shifted due to mechanical vibration, etc., or the N transposition is immature, so make sure to move the operating lever to the stopping point. It becomes difficult to set, and this also poses a safety problem.

Therefore, when the control lever is positioned near the neutral position,
To ensure that the vehicle, etc. in question is stopped.

2. Description of the Related Art Devices in which a linkage mechanism between an operating lever and a swash plate is provided with play are conventionally known.

Generally, when the swash plate plunger pump reaches near the neutral point,
Furthermore, it is known that a self-returning force is generated to try to return to the neutral point, but this conventional device utilizes the self-returning force within the range of the above-mentioned wobbling.

(Problems to be Solved by the Invention) In the conventional device as described above, the magnitude of the neutral point return moment of the swash plate varies depending on the characteristics and operating conditions of each individual pump, so it is difficult to stabilize the device. There was a problem that recovery characteristics could not be obtained.

Therefore, the inventors of the present invention repeatedly conducted various experiments and found that when the cylinder block easily moves in a direction perpendicular to the tilting direction of the swash plate, the neutral point return moment of the pump increases.

This type of swash plate plunger pump has a cylinder block connected to the input shaft by a spline.
Both of them have backlash, but this invention utilizes this backlash to make the cylinder block easier to move.

That is, an object of the present invention is to provide a swash plate plunger pump in which the cylinder block can be easily rotated in a direction substantially perpendicular to the tilting direction, and the neutral point return moment thereof can be increased.

(Means for Solving Problems) In order to achieve the above object, the present invention provides a cylinder block that is spline-coupled to an input shaft and has no backlash with respect to the input shaft, and a cylinder block that is slidably attached to the cylinder block. A plunger provided on the plunger, a swash plate on which a shoe provided on the head of the plunger slides, and a valve plate that makes surface contact with the cylinder block on the opposite side of the swash plate, and controls the tilt angle of the swash plate. In a swash plate plunger pump with variable discharge volume, the cylinder block and valve plate are integrated and are configured to be rotatable only in a direction approximately perpendicular to the direction in which the swash plate is tilted. .

(Operation of the present invention) In this invention, since the valve plate can rotate in a direction substantially perpendicular to the tilting direction, the rotation of the cylinder block is not restricted by the valve plate, and the cylinder block can rotate accordingly. It becomes easier to do.

(Effects of the Present Invention) As described above, since the cylinder block is likely to move in a direction substantially perpendicular to the tilting direction, its neutral point return moment becomes large. therefore.

If the operating lever is returned to the neutral position to some extent, the tilting angle becomes zero due to the self-returning force, and the vehicle can be reliably stopped.

(Embodiment of the present invention) In the first embodiment shown in FIG. 1.2, the cylinder block 11 is connected to the input shaft 12 by a spline, so the cylinder block 11 may wobble with respect to the input shaft 12. That's what I do.

The cylinder block 11 thus constructed is provided with a plurality of plungers 14 each having a shoe 13 formed on its head, and the shoe 13 is brought into sliding contact with the swash plate 15.

This swash plate 15 rotates around the trunnion pin 18, and depending on the tilt angle, the plunger! By adjusting the maximum stroke of No. 4, the discharge amount can be controlled.

In other words, if the tilting angle is increased, the stroke of the plunger also becomes larger, so the discharge amount also increases, and the speed of the vehicle etc. also increases.

If the tilt angle is set to zero, the stroke will also be set to zero, so the discharge amount will be set to zero, and the vehicle or the like will stop.

A valve plate 17 is provided on the side surface of the cylinder block 11 thus constructed, that is, on the side opposite to the swash plate 15, and the cylinder block 11 and the valve plate 17 are brought into surface contact.

Valve plate 17 on the side opposite to the contact surface of seal block 11
An arcuate protrusion 18 is formed on the side surface of the seal block 11 in the radial direction, and the port block 18 facing the seal block 11 has four parts 2 that engage with the protrusion 18.
0 is formed.

A gap is formed between the valve plate 17 and the boat block 18, and the valve plate 17 can rotate around the protrusion 18 within the range of this gap.

However, the protrusion 18 is connected to the trunnion pin 1 of the swash plate 15.
Since the valve plate 17 is formed in a direction perpendicular to the swash plate 8, the valve plate 17 can only be rotated in a direction substantially perpendicular to the direction in which the swash plate 15 is tilted. The fact that the valve plate 17 rotates only in the direction orthogonal to the tilting direction of the swash plate means that the cylinder block 11 that is in surface contact with the valve plate is also restricted in its rotational direction. In other words, as described above, the cylinder block 11 maintains a play with respect to the input shaft, so it can rotate in all directions within the range of the play, but as described above, the cylinder block 11 can rotate in all directions with the valve plate 17. Since the direction of movement is restricted, the cylinder block 11 can also rotate integrally with the valve plate only in a direction orthogonal to the tilting direction.

The boat block 18 is provided with a pressure spring 21, which causes the pressure spring to act on the valve plates 1 and 7, and is also provided with an adjustment screw 22 for adjusting the spring force of the spring 21.

The reason why the spring force of the pressing spring 21 is applied to the valve plate 17 in this way is to maintain the orientation of the valve plate 17 and to maintain the close contact between the cylinder block 11 and the valve plate 17. Further, by adjusting the spring force of the spring 21 using the adjustment screw 22, the contact resistance between the protrusion 18 and the recess 20 can be adjusted.

Then, by operating an operation lever (not shown), the swash plate 15
The tilt angle of the input shaft 12 is made larger than zero, and the input shaft 12
When the cylinder block 11 is rotated at the same time, the plunger! 4 reciprocates while being guided by the swash plate 15, and discharges a discharge amount according to the tilt angle.

Since this pump function itself is completely the same as the conventional one, detailed explanation thereof will be omitted.

Then, when the operating lever is returned to near the neutral position from the above state and the tilting angle of the swash plate 15 is made close to zero, the cylinder block 11 is integrated with the valve plate 17 as described above, and the tilting Since it rotates in the direction perpendicular to the angle, the moment for returning to the neutral point becomes large. Therefore, by utilizing this large self-returning force, the swash plate pump can be reliably returned to the neutral position.

In addition, cylinder block 1! In order to improve the followability between the valve plate 17 and the valve plate 17, the diameter of the arcuate surface of the protrusion 18 must be smaller than the pitch circle diameter of the arrangement position of the plunger 14 with respect to the cylinder block 11.

As described above, in this first embodiment, the protrusion 18 is provided on the valve plate 17.
, and the recess 2o is formed in the boat block 19, but it goes without saying that the recess may be formed in the valve plate and the protrusion may be formed in the boat block.

Further, although the protrusion 18 is formed integrally with the valve plate 17 or the boat block, a connector is provided on either one of the valve plate or the boat block, a recess is formed on the other, and these connectors and the recess are connected. They may be made to match.

Further, although the protrusion IB is formed to be long in the radial direction of the valve plate 17, the protrusion or the connector may be made spherical. Due to the thrust, the cylinder block 11 rotates only in a direction substantially perpendicular to the tilt angle.

In the second embodiment shown in FIG.
3, the trunnion 23 rotatably supports the valve plate 17, and the trunnion 23 rotatably supports the valve plate 17. 3 is provided with a flow path 24 for discharge and suction. A pressing spring 2B is provided on a body 25 provided facing the valve plate 17, and the spring force of the pressing spring 2B is applied to the valve plate 17.The other configuration is the same as that of the first embodiment. It is.

In each of the embodiments described above, an oil film is formed on the protrusion 18 or the sliding contact portion of the connector, and this oil film performs a lubricating function.

However, when the thrust force of the plunger 14 due to positive liquid increases, the pressing force of the sliding contact section increases, which increases the frictional force, which may impede the smooth movement of the sliding contact section.

Therefore, in order to prevent such a phenomenon, it is necessary to provide a means for canceling the thrust of the plunger 14 to ensure smooth movement of the sliding contact portion. This is the third embodiment shown in FIG.

In this third embodiment, the valve plate 17 is provided with pistons 2B, 2B for canceling the plunger thrust. In other words, the valve plate! 7, a pair of pressure chambers 27.27 communicating with the plunger 14 side are formed in symmetrical positions, and these pressure chambers 27.2? Pistons 25 and 25 are installed inside via springs 2B and 28, and this piston is brought into contact with the port block 18.

Therefore, a thrust force approximately equal to that of the plunger 14 acts on the port block via the piston 2B, so the thrust force of the plunger 14 is canceled and the protrusion or connector portion is smoothly lubricated.

It goes without saying that the number and size of the pistons 2B may be determined depending on the thrust of the plunger 14.

The fourth embodiment shown in FIG.
Adjustment pistons 30, 30 are provided at the tips of the pistons 111, and the pressing force of the pistons 2B, 2B can be adjusted depending on the position of the adjustment pistons.

The fifth embodiment shown in FIG. 6 is provided with a hollow piston 31.31 on the port block 19 side, and this hollow piston 31.31 secures a certain amount of clearance with the pressure chamber 32.32. Even if the valve plate 17 is tilted, the hollow piston 31, 31 can follow it.

Therefore, in this fifth embodiment, the hollow piston 31.3
The pressure introduced into the spring 28.28 cancels the thrust force, but makes it possible to adjust the spring force of the pressure spring 28.28 by means of the adjusting screw 29.28.

In any case, in each of the embodiments described above, when the operating lever is operated to bring the tilting angle of the swash plate 15 to near zero, the cylinder block 11 returns to near the neutral position, and due to the action of its own return moment, This will ensure a return to the neutral point.

[Brief explanation of drawings]

Drawings 1.2 show the first embodiment of this invention,
FIG. 1 is a front view, FIG. 2 is a sectional view of the main part, and FIGS. 3 to 6 are sectional views of the main part showing second to fifth embodiments of the present invention. 11... Cylinder block, 12... Input shaft, 1
3...shoo! 4...Plunger, 15...
Swash plate, 17...valve plate.

Claims (1)

[Claims] A cylinder block spline-coupled to the input shaft and held against the input shaft, a plunger slidably provided on the cylinder block, and a swash plate on which a shoe provided on the head of the plunger slides. , comprising a valve plate that makes surface contact with the cylinder block on the opposite side of the swash plate,
In the above-mentioned swash plate plunger pump in which the discharge amount is made variable by controlling the tilt angle of the swash plate, the cylinder block and the valve plate are integrated, and the cylinder block and the valve plate are integrated so that only the cylinder block and the valve plate can be moved in a direction substantially perpendicular to the direction in which the swash plate is tilted. Rotatable swash plate plunger pump.