JPS6228506A - Servo motor structure of hydraulic machine - Google Patents

Abstract

PURPOSE:To prevent the occurrence of one-sided contact and abnormal one-sided wear of a bearing part, by a method wherein a rotatable bush, capable of following inclination of a piston rod, is engaged with a cylinder cover. CONSTITUTION:A bush 21, formed with an outer and an inner wheel and having a contact surface formed in a spherical shape, is placed to the inner side of a cylinder cover 9. This enables each bearing to follow inclination of a piston rod 8, resulting in the possibility to prevent the occurrence of one-sided contact and one-sided wear of a bearing part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a servo motor for operating guide vanes of a hydraulic machine, and particularly relates to a servo motor structure suitable for receiving an axis-perpendicular load acting on the servo motor. .

[Background of the invention]

Conventionally, as described in Utility Model Publication No. 57-51803,
Although it has been considered to reduce the load acting on the cylinder cover bushing, it has not been possible for the bushing to follow the inclination of the piston rod. Further, as described in Japanese Utility Model Publication No. 115485/1985, the outer periphery of the bushing has a cylindrical shape and is not designed to follow the inclination of the piston rod.

The prior art will be explained with reference to FIGS. 3 to 6.

FIG. 3 shows a conventional servo motor structure, in which pressure oil inlets and outlets a and b are provided at both ends of a hydraulic cylinder 5, and a piston 6 is built into the cylinder 5. A piston rod 8 is fastened to the piston 6 by a piston tightening nut 7. Since the contact surfaces C and d between the piston 6, the piston rod 6, and the piston tightening nut 7 are flat, respectively, one end of the hydraulic cylinder 5 where the outer periphery of the piston 6 also tilts with respect to the tilt of the piston rod 8. is closed by a cylinder cover 9, and a bush 10 is provided inside the cylinder cover as a bearing for the piston rod 8. Since the outer periphery of the bushing 10 is inserted and fixed into the cylinder cover 9 by tight fit, the inner periphery of the bushing 10 does not tilt relative to the tilt of the piston rod 8. Furthermore, a gasket 11 is provided at the tip of the cylinder cover 9 to prevent oil leakage from the piston rod 8.
It is pressed down by a gasket presser 13. sim 12
In order to adjust the tightness of the packing, press the packing presser 1.
3 and the cylinder cover 9. In the figure, 1 is a base, 2 is a foundation bolt, 3 is an adjustment liner, and 4 is a bolt.

Next, the axis-perpendicular load acting on the piston rod 8 will be explained with reference to FIGS. 4 and 5.

FIG. 4 shows a plan view, and the servo motor 14 is connected to the guide ring 16 via the horizontally rotatable connection joints 17, 18 and the connection link 15, and the operating pressure oil is connected to the boat a and the By moving in and out of port b, the piston 6 reciprocates and opens and closes the guide ring 16. Here, due to the arc movement of the guide ring 16, the lateral force F□ or F of the servo motor output Fc or FO is
2 is received by the connecting joint 17 at the tip of the piston rod 8,
The reaction force F3 or F4 is generated at 10 parts of the bushing. In addition, in the piston 6 part, F6 or F6
A reaction force is generated and is received by the bush 10 and the piston 6, respectively. At this time, the lateral load F and F
The size of the connecting link 1 relative to the core of the servo motor 14 is such that the connecting joint 17, 18 can rotate horizontally.
A component force due to the inclination of 5 will act.

FIG. 5 is a cross-sectional view of the connecting part from the servo motor 14 to the guide ring 16, and the connection method and operation are almost the same as in FIG. 4 described above, but only the differences will be explained below. .

The upper cover (not shown) to which the guide ring 16 is attached is distorted and Δ
Only H stands out. Therefore, when installing the servo motor (when no water pressure acts on the hydraulic machine), the core of the servo motor 14 is installed higher than the guide ring 16 by 1/2 ΔH, which is half of ΔH, so that water pressure does not act on the hydraulic machine. and when.

A servo motor 14 is installed in the middle when it is not working.

Here, the connecting joints 17 and 18 are such that the connecting link 15 is ΔH
In order for the connecting link 15, which has a structure with a gap so as to move upward and downward, to move upward and downward, an axis-perpendicular load F7 or F acts on the tip of the piston rod. Furthermore, if the horizontal level of the servo motor is out of order, the position of the connecting joint 17 will be too high or too low, and the connecting link 15 will not be able to slide by an amount corresponding to 68 degrees of floating of the guide ring 16.

However, since the position of the guide ring 16 and the position of the connecting joint 17 are mechanically constrained, the connecting link 15 and the piston rod 8 will bend to correspond. The axis-perpendicular load at this time is much larger than FitF2 t F7 ,F. Therefore, a large force acts on the bushing 10 and the piston 6, which abnormally accelerates the wear of the bush 10 and the inner surface of the cylinder, and even causes a jamming phenomenon.

Next, referring to FIG. 6, a description will be given of how each bearing portion hits when receiving a load perpendicular to the axis. Due to the action of the axis-perpendicular load F7 on the tip of the piston rod 8, the piston rod 8 and the piston 6 are tilted within the range of each bearing gap, as shown in the figure, and the piston rod 8 and the piston 6 are tilted at the point f of the bush 10 and the piston 6.
It will hit at point g. Here, the length of the bush 10 and the length of the piston 6 are determined so that the average surface pressure σ is within a certain value. That is, σ=F/DXL σ; average surface pressure F; load D; bearing diameter L; , is inversely proportional to the bearing diameter. Despite this design, the actual machine hits at point 19 g and slides under high local surface pressure.
It will hit one side and wear out on one side. Under high local surface pressure, it cannot withstand it and rapidly wears out on one side until it reaches a point where it can withstand it and stabilizes. This one-sided wear further increases the inclination of the piston rod 8, and eventually the inner periphery of the packing holder 13 and the outer periphery of the piston rod 8 come into contact as shown in FIG. 3, leading to a jamming phenomenon. .

In addition, the inner circumferential wear powder of the cylinder 5 mixes with the operating oil and causes other precision control equipment to malfunction.

[Purpose of the invention]

An object of the present invention is to provide a servo motor structure for a hydraulic machine in which a rotatable bearing is used as the servo motor bearing so that the bearing can follow the inclination of a piston rod.

[Summary of the invention]

The present invention focuses on the fact that the servo motor bearing is uneven and wears on one side, and makes the actual product match the bearing average surface pressure (σ = F / D X L) managed in the bearing design. In order to achieve this, if the bearing follows the tilt of the piston rod and tilts, the entire surface of the bearing will hit instead of hitting one side.Based on this idea, we designed a servo motor structure for hydraulic machines that uses rotatable bearings. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Pressure oil ports a and b are provided at both ends of the hydraulic cylinder 5, and a piston 6 is incorporated into the cylinder 5. Washers 19 and 20 are applied to both sides of the piston 6, and the piston rod 8 is tightened with a piston tightening nut 7 so that the piston 6 can rotate. Washer 1.
The contact surface between 9.20 and the piston 6 is spherical, and it slides on a spherical surface against the inclination of the piston rod, and the outer circumferential surface of the piston 6 can maintain a position parallel to the inner surface of the cylinder 5. . Further, one end of the cylinder 5 is closed with a cylinder cover 9, and inside the cylinder cover 9,
A bushing 21 is provided as a bearing for the piston rod 8.

The bushing 21 consists of an outer ring to facilitate attachment to the cylinder cover 9 and an inner ring to serve as a bearing for the piston rod. The inner ring moves and the inner surface of the bushing 21 maintains a position parallel to the piston rod 8.

FIG. 2 shows a state in which the piston rod 8 is tilted, and the inner surface of the cylinder 5 and the outer surface of the piston 6 are parallel.
The contact surface is the entire length of the piston 6. Similarly, for the bushing 21, the piston rod 8
The outer surface and the inner surface of the bushing 21 are parallel, and the contact surface is a plane Q that is the entire length of the bushing.

According to this example, the surface pressure of each bearing is as designed, σ=
F/D

〔Effect of the invention〕

According to the present invention, since each bearing can follow the inclination of the piston rod, it is possible to prevent one-sided contact and abnormal one-sided wear of the bearing part, and furthermore, it is possible to prevent the phenomenon of the piston rod and the seal retainer getting stuck together. can.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a servo motor according to an embodiment of the present invention;
Fig. 2 is a diagram showing the effect of one embodiment, Fig. 3 is a sectional view of a conventional servo motor, Figs. 4 and 5 are system diagrams showing conventional operation and load, and Fig. 6 is a diagram showing the conventional servo motor. , is a sectional view showing the contact of a conventional bearing. 5... Cylinder, 6... Piston, 7... Piston tightening nut, 8... Piston rod, 9... Cylinder cover, 19.20... Washer, 21... Bush.

Claims (1)

[Claims] 1. A hydraulic cylinder having operating pressure oil inlets and outlets at both ends, a piston that can reciprocate within this hydraulic cylinder, and a piston rod that is connected to this piston and that reciprocates together with the piston. , a cylinder cover that closes one end of the hydraulic cylinder, a bush that is fitted to the cylinder cover and receives the piston rod, a packing whose outer periphery is in contact with the cylinder cover and whose inner periphery is in contact with the piston rod, and a packing presser that presses down the packing. A servo motor structure for a hydraulic machine, characterized in that a rotatable bush that can follow the inclination of the piston rod is fitted into the cylinder cover.