JPH0559276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is characterized in that one end of a plunger accommodated in a hole of a rotating cylinder drum is supported by a swing plate, and in order to change the discharge amount, the swing plate It is possible to set a large plunger stroke around the oscillation axis formed in the housing against the force of the spring, and the oscillation axis of the oscillation plate moves toward the top dead center with respect to the axis of the cylinder drum. Concerning a misaligned axial plunger pump.

[Conventional technology]

Such known plunger pumps use an operating position which is subjected to mechanical or hydraulic forces to set the tilted position of the rocking plate, also called swash plate.
This allows all discharge amounts to be set continuously between the minimum and maximum values. In particular, in many applications, it is a disadvantage that attention must be paid to the position of the minimum delivery volume, in order to ensure that a small delivery volume is always available for lubricating and cooling the pump parts.

[Problem to be solved by the invention]

An object of the present invention is to provide an axial plunger pump that can automatically set the swing plate from a minimum discharge amount to a large discharge amount without requiring any special means.

[Means to solve the problem]

In order to solve this problem, according to the present invention, the rocking axis of the rocking plate is in the plane formed by the support point of the plunger on the rocking plate, and when the axial plunger pump is not loaded, only a small discharge amount is produced. The force of the spring is sized to return the rocker plate to its original position.

〔Effect of the invention〕

Thus, according to the invention, the force of the spring is dimensioned in such a way that when the pump is not loaded, it returns the rocker plate to a position that produces only a small displacement, so that when no load is connected, i.e. If there is no pressure in the load, the minimum discharge rate is automatically set. In addition, since the rocking axis of the rocking plate is on the plane formed by the plunger support point on the rocking plate, that is, the point of action of the plunger that receives the pressure of the discharge amount, a large discharge amount can be achieved without the need for special means. The setting of the rocking plate is also performed automatically.

〔Example〕

An embodiment of the invention is shown in the drawing and will be described below.

In FIG. 1, a housing 10 of an axial plunger pump, which is formed approximately in the shape of a bowl, has a lid 11.
Closed by. The lid 11 and the housing 10 are provided with bearings 12 and 13 for a drive shaft 14 that extends longitudinally through the entire housing. A cylinder drum 15 is fixedly connected to the drive shaft 14, and a plurality of holes 16 extending parallel to the drive shaft 14 are formed in the cylinder drum 15, in which a plunger 17 slides. The hole 16 is conventionally reduced to a significantly smaller diameter 18 on the side closer to the lid 12. Lid 1
1 has control means for introducing and removing the pressure medium in a known manner. These are not shown as they are not important to the invention.

One end of the plunger 17 is in contact with a disk 20, which is supported by a swing plate 22 via a roller support piece 21 and a guide support piece 21' (sliding bearing or rolling bearing). This rocking plate 2
2 extends at right angles to the axis 14' of the drive shaft 14 and is located at the top dead center by a dimension e with respect to this axis 14'.
It can swing around an axis 23 shifted toward the OT side. Bottom dead center is indicated by UT. Furthermore, the center of the axis 23 is located precisely on the end face 20' of the disk 20 which is closer to the plunger 17.

The plunger 17 is formed hollow, and the hollow space 2
A spring 26 is located within 5 and keeps the plunger 17 pressed against the end face 20' of the disc 20.

The rocking plate 22 has an extension 27 on the side of the top dead center OT, and a substantially hemispherical recess 28 is formed in the plunger-side surface of the extension 27. This recess 2
A columnar body 30 with an end 29 that fits into the rocker plate 22 has a flange-like edge 31 on the side closer to the rocking plate 22 , on which one end of a spring 32 is supported.
The other end is in contact with the lid 11. The columnar body 30 is the lid 1
This corresponds to the screw shaft 34 supported in the screw hole 35 of No. 1. A set screw 36 is provided in the housing 10 axially opposite the screw shaft 34 and serves as a slipper for the rocking plate 22. When the set screw 36 hits the rocker plate 22, the pump is in the minimum discharge position.

FIG. 3 shows a front view and a side view of the rocking plate.

Resultant pressing force of the plunger during operation of this pump
Fres acts on the swing plate 22, and at a small swing angle, the resultant force of the spring 26 acts on the swing plate 22 in the direction of the large swing angle, that is, in the direction of increasing the discharge amount. This is because the resultant force acts on the swing plate 22 at the lever arm length e with respect to the axis 23. P
indicates the center of gravity of the plunger force. The letter D indicates the discharge side, and the letter S indicates the suction side.

The force of the spring 32 acts to return the rocking plate 22, and at a large rocking angle, the resultant force of the plunger spring 26 acts. This consideration ignores dynamic forces.

Importantly, at small pressures up to about 10bar the pump is set to its minimum delivery position;
This is how the spring 32 is designed. spring 32
The force is greater than the Plancia force at pmin. When the load is connected, the system pressure increases, and the plunger force P, which becomes dominant at that time, causes the pump to deliver the discharge amount set by the screw shaft 34 due to the mechanism described above. At this time, the columnar body 30 hits the screw shaft 34.

This arrangement has the advantage that it is not necessary to overcome the throttling resistance of the regulator when setting the pump, which helps with the setting time. In this pump, when the load is disconnected, the automatic return of the pump reduces the circulation loss output of the system. Furthermore, this device
When the pump is returned, no force acts on the screw shaft 34 (maximum oscillation), which allows the screw shaft 34 to be easily manipulated.

The embodiment shown in FIG. 2 is different from the embodiment described above.
The only difference is that the return device for the rocker plate 22 is constructed slightly differently. The screw shaft corresponding to the screw shaft 34 in the previous embodiment is 4 here.
A plunger 41, indicated by 0 and supported by this screw shaft 40, is connected to a sleeve 42 screwed into the lid 11.
It is guided to slide upwards. A spring 43, which corresponds to the spring 32 in the previously described embodiment, acts on the plunger 41. Screw shaft 40 and sleeve 42
An annular space 44 is formed between them, and any control pressure can be applied to this annular space 44 via a housing hole 45. This control pressure can be obtained from a second pressure circuit or generated by a small control oil pump via an adjustable pressure limiting valve or throttle.

This embodiment has the advantage that the rocking plate 22 can be returned even at high system pressures by increasing the control pressure. All other functions are the same as described above. What can be said for both embodiments is that the automatic rocking of the rocking plate provides an alternative to the so-called load sensing system, ie a hydraulic system with low losses.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken through the center axis of a first embodiment of an axial plunger pump, FIG. 2 is a similar sectional view of the second embodiment, and FIG. 3 is a diagram illustrating the action of the rocking plate. 10... Housing, 14... Rotating shaft, 14'
... Axis line, 15 ... Cylinder drum, 17 ... Plunger, 22 ... Rocking plate, 23 ... Rocking axis line,
32...Spring.

Claims (1)

[Claims] 1. One end of the plunger 17 accommodated in the hole 16 of the rotating cylinder drum 15 is supported by a swing plate 22, and the swing plate 22 is formed within the housing to change the discharge amount. A large plunger stroke can be set around the pivot axis 23 of the pivot plate 22 against the force of the spring 32.
is shifted toward the top dead center OT with respect to the axis 14' of the cylinder drum 15, the rocking plate 2
2 is in the plane formed by the support point of the plunger 17 on the oscillating plate 22, and when the axial plunger pump is not loaded, the oscillating plate 22 is returned to a position that produces only a small discharge amount. , an axial plunger pump characterized in that the force of the spring 32 is dimensioned. 2. characterized in that the force of the spring 32 is controllable via a plunger 41 that receives control hydraulic pressure;
A pump according to claim 1. 3. Pump according to claim 2, characterized in that the control hydraulic pressure is generated by the auxiliary pump via an adjustable pressure limiting valve or throttle.