JPS6354146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a displacement control mechanism for a positive displacement fluid machine, that is, a variable displacement axial piston machine, which transfers and receives energy using the static pressure of a fluid.

Hydraulic pumps, hydraulic motors, and the like are well known as such machines. Generally, the capacity adjustment work of variable displacement axial piston machines, that is, the discharge amount in the case of a hydraulic pump, or the rotation speed and output in the case of a hydraulic motor, is done by adjusting the tilt angle of the swash plate that the piston contacts. It is carried out with
Hereinafter, this type of machine will be abbreviated as a piston machine. A cylinder is fixed to the rotating shaft, and a plurality of pistons installed in this cylinder are
One end of the piston is in contact with a swash plate, and when the tilt angle of the swash plate is changed, the stroke of the piston is changed and the displacement is changed.

By the way, in this type of piston machine,
As is well known, the positional relationship of the piston changes periodically with respect to the tilting center axis of the swash plate due to the rotation of the rotating shaft and thus the cylinder. For this reason, when fluid pressure is generated within the cylinder, a fluctuation moment is generated in the swash plate around the tilting center axis due to the reaction force thereof, and the tilting rotation center axis vibrates in an oscillating manner. The absolute value and amplitude of this moment are generally large and cannot be stopped by simple frictional force or human power without the use of auxiliary means. In addition to controlling vibrations, the tilting angle of the swash plate is adjusted.

However, this type of force multiplier has the drawbacks of being complex and expensive, and also has the drawback that the hydraulic cylinders and the like generate pulsations due to the hydraulic pressure, making it impossible to obtain complete vibration damping.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a displacement control mechanism for a variable displacement axial piston machine that can prevent rocking of a tilting center shaft using a relatively simple device.

According to the present invention, there is provided a piston machine having a cylinder containing a plurality of pistons, and a swash plate having one end of the pistons in contact with each other to give reciprocating motion to the pistons and whose stroke can be changed by changing the tilting angle of the pistons. In a displacement control mechanism for a pair of variable displacement axial piston machines in which the reaction force moments that the swash plates receive from the pistons are substantially equal, the pair of piston machines are arranged in symmetrical positions, and the pair of swash plates are provided symmetrically with equal inclination angles, a worm wheel is fixed to the central axis of each of the pair of swash plates, and these worm wheels mesh with the worm,
Those worms have teeth in opposite directions,
It is supported by a control shaft, so that the reaction force moment is offset.

In other words, when a pair of piston machines operates, a moment is generated in a pair of swash plates in mutually opposite directions around the center axis of tilting, and that moment is applied to a control shaft through a pair of worm wheels and a worm, and a tensile force is generated on the control shaft. Or, since it acts as a compressive force, the reaction moment is canceled out. Since the pair of worms and the worm wheel are engaged, a surge phenomenon does not occur unlike the hydraulic cylinder type, and as a result, the vibration force of the swash plate is suitably suppressed. Furthermore, since a gear mechanism is used, there is no need to take measures against oil leakage, and manufacturing and maintenance are simple, and the entire device is smaller and lighter.

An embodiment of the present invention will be described below with reference to the drawings. Referring now to FIGS. 1 and 2, a pair of piston mechanisms 20, 20' are arranged in symmetrical positions so that each piston mechanism receives approximately the same reaction force moment on its respective swash plate.
That is, since the illustrated embodiment uses the same type of piston machine, one of the piston machines will be designated by a slash symbol and redundant explanation will be omitted. A rotating shaft 2 is supported by a bearing 3 on a substantially rectangular frame 1, and a cylinder 4 is fixed to the rotating shaft 2. A plurality of pistons 5 are arranged in the axial direction within the cylinder 4, one end of which is in contact with a swash plate 6, and a plurality of compression chambers 7 corresponding to each other are formed at the other end. The compression chamber 7 is connected to an external mechanism (not shown) via each oil passage 8 provided in the valve body V. Note that the connection relationship between the valve body V and the cylinder 4, that is, the piston mechanism 2
When 0 is a pump, the connection relationship of flow paths for sucking and discharging fluid is well known, and therefore a description thereof will be omitted. The swash plate 6 is supported by a tilting central shaft 9, which is supported by bearings 10, 10 of the frame 1, and as shown in the figure, the pair of swash plates 6, 6' They are arranged symmetrically and with equal inclinations.

A worm wheel 11 is fixed to the end of the tilting shaft 9 of the swash plate, and this wheel meshes with a worm 12 on a control shaft 13.

In the meshing between the worm wheel and the worm, the transmission efficiency is good in one direction and bad in the other direction, so even if the worm wheel 11, 11' tries to rotate, the worm 12, 1 that is meshing with it
2' does not rotate. Further, as shown in FIG. 2, the worms 12, 12' have threads or valleys in opposite directions, so when the control shaft 13 is rotated by any means, the rotational force is transferred to the worm wheels 11, 11. 'Therefore, it is transmitted to the swash plates 6, 6', which are adjusted to the same angle, ie the same volume.

Since the present invention is configured as described above,
When the piston machines 20, 20' operate, the swash plate 6,
Even if a moment is generated in the control shaft 6', for example in the directions indicated by arrows A and A' in FIG. 2, this moment acts as a tensile force on the control shaft 13 via the worms 12 and 12'. The reaction moments are therefore canceled out. It is clear that even if the instantaneous moment is in the opposite direction to arrows A and A', it will act as a compressive force on the control shaft, but it will be canceled out in the same way.

When the control shaft 13 is rotated by any means in order to change the capacity of the piston machines 20, 20', the worm wheels, worms, etc. are formed with the same size and pitch but only in different directions. The swash plates 6, 6' are rotated by the same tilting angle.
This rotational operation is possible with a small force because the control shaft 13 is supported by bearings 14, 14, and the transmission is from the worm to the worm wheel.

As explained above, according to the present invention, since the tilting central axes of the pair of swash plates are mutually connected by the worm wheel and the worm, the reaction moment of the swash plates is effectively canceled out. In this case, since it relies on a gear mechanism consisting of a worm wheel and a worm, a surge phenomenon does not occur unlike in the hydraulic cylinder system, and the vibration force of the swash plate is more completely suppressed. Furthermore, since it is a gear mechanism, there is no need to take measures against oil leakage, and it is easy to manufacture and maintain. Furthermore, it is more compact than a hydraulic system such as a hydraulic cylinder, and is therefore useful for reducing weight.

It is clear that the invention can also be applied to oblique piston machines.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG.
The figure is a side view of the main parts. 4...Cylinder, 5,5...Piston, 6...
Swash plate, 9... Tilt center axis, 11... Worm wheel, 12... Worm, 13... Control axis.

Claims (1)

[Claims] 1 Consisting of a piston machine having a cylinder containing a plurality of pistons, and a swash plate with one end of the pistons in contact to give reciprocating motion to the pistons and whose stroke can be changed by changing its tilt angle, In a displacement control mechanism for a pair of variable displacement axial piston machines in which plates receive substantially equal reaction moments from the piston, the pair of piston machines are arranged in symmetrical positions, and the pair of swash plates are symmetrically equal. installed at an angle,
A worm wheel is fixed to the tilting center axis of each of the pair of swash plates, these worm wheels mesh with the worms, the worms have teeth facing in opposite directions, and are supported by the control shaft. 1. A displacement control mechanism for a variable displacement axillary piston machine, wherein the reaction force moment is offset.