JPH0637641U - Fluid pressure type shock absorber - Google Patents

Abstract

(57) [Summary] [Object] A fluid pressure type shock absorber which absorbs kinetic energy of a load by a fluid such as hydraulic pressure is intended to reduce the fluctuation of the shock absorbing action due to temperature change. [Structure] When the piston 15 moves in the pressure tube 12, the fluid in the pressure tube flows out from the throttle hole, and a back pressure in the pressure tube based on the resistance to flow out from the throttle hole exerts a buffering action. In the fluid pressure shock absorber described above, an inner cover 14 for closing the inside of the pressure tube is provided at a position corresponding to the bottom surface of the pressure tube, and at least one of the throttle holes is provided in the inner cover. An eccentric cam 21 for adjusting the area of the opening of the aperture provided in the cover is provided so as to be operable from the outside.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a fluid pressure type shock absorber that absorbs kinetic energy of a load by a fluid such as hydraulic pressure, such as a shock absorber that absorbs shock and vibration when the load is stopped, or a hydro checker for controlling the speed of the load. Used as.

[0002]

[Prior art]

 Generally, in a hydraulic shock absorber, a piston moves in a pressure tube having a plurality of holes arranged along the axial direction, so that the pressure oil in the pressure tube flows out from the hole and the pressure oil flows from the hole. The back pressure in the pressure tube based on the resistance (outflow resistance) when the oil flows out exerts a buffering effect.

Further, since the magnitude of the buffering action is adjusted according to the magnitude of the kinetic energy of the load, the outflow resistance of the pressure oil from the hole can be variably adjusted. FIG. 4 is a sectional view showing an adjusting mechanism of a conventional hydraulic shock absorber 80.

In the conventional hydraulic shock absorber 80, in order to adjust the outflow resistance of the pressure oil HY, the shaft having an inner diameter substantially equal to the outer diameter of the pressure tube 81 and corresponding to the hole 82 of the pressure tube 81. The metering tubes 84 each having an orifice 85 at each of the directional positions are arranged coaxially with the pressure tube 81, and communicate with each hole 82 on the outer peripheral surface of the pressure tube 81, and the bottom portion is with respect to the outer peripheral circle. An eccentric eccentric groove 83 is formed over a central angle of about 180 degrees.

The outflow resistance in this case increases or decreases according to the viscosity length L along the arc from the point a at which the eccentric groove 83 is raised to the point b at which the orifice 85 is present, so the pressure of the metering tube 84 is reduced. The rotational angle position with respect to the tube 81 is varied to adjust the viscosity length L, and thereby the outflow resistance of the pressure oil HY is adjusted.

[0006]

[Problems to be solved by the device]

 However, in the above-described conventional hydraulic shock absorber 80, since the outer peripheral surface of the pressure tube 81, the inner peripheral surface of the metering tube 84, the eccentric groove 83, and the like are required to have high processing accuracy, the manufacturing cost increases. .

Further, since the resistance to the pressure oil HY is increased / decreased by variably adjusting the viscosity length L, it is easily affected by the fluctuation of the viscosity coefficient due to the temperature change of the pressure oil HY, and the buffering effect by the temperature change is caused. , That is, the fluctuation of the performance of the shock absorber 80 was large.

In particular, when the mass or the propulsive force of the load is large and the speed is small, it is necessary to increase the outflow resistance of the pressure oil HY particularly in order to obtain a sufficient cushioning action. With 80, the amount of pressure oil outflow could not be fully squeezed by adjustment. Therefore, it is necessary to increase the pressure receiving area of the piston, which causes a problem of increasing the size of the device.

In view of the above-mentioned problems, the present invention eliminates the need for a metering tube that requires high accuracy, reduces cost, and reduces the fluctuation of the cushioning action due to temperature changes, thus increasing the size of the device due to insufficient throttling. It is an object of the present invention to provide a fluid pressure type shock absorbing device which does not invite.

[0010]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the device according to the invention of claim 1 moves the piston in the pressure tube so that the fluid in the pressure tube flows out from the throttle hole and flows out from the throttle hole. In a fluid pressure type shock absorber in which a back pressure in the pressure tube based on resistance exerts a cushioning action, a pressure control device for closing the inside of the pressure tube at a position corresponding to the bottom surface of the pressure tube. An inner cover is provided, at least one of the aperture holes is provided in the inner cover, and an adjustment member for adjusting the area of the opening of the aperture hole provided in the inner cover is provided from the outside. It is provided so as to be operable.

In the device according to the invention of claim 2, the inner cover is provided so as to be movable in the axial direction with respect to the pressure tube, and the adjusting member is centered on an axis line along the moving direction of the piston. It is a rotatable eccentric cam.

In the device according to the third aspect of the present invention, the piston is provided with packing for sealing between the piston and the pressure tube.

[0013]

[Action]

 The area of the opening of the aperture hole is adjusted by the adjusting member. As a result, the resistance of the fluid flowing out from the throttle hole is variably adjusted, and kinetic energy is absorbed according to the speed of the load.

When the inner cover is provided so as to be movable in the axial direction with respect to the pressure tube, the inner cover comes into contact with the eccentric cam due to the pressure caused by the movement of the piston, etc., and the opening area of the throttle hole rotates the eccentric cam. It is adjusted according to the angular position.

[0015]

【Example】

 1 is a sectional front view of a shock absorber 1 according to the present invention, FIG. 2 is a view for explaining the action of an adjusting device 20 of the shock absorber 1 of FIG. 1, and FIG. 3 is a stroke and an orifice area of the shock absorber 1. It is a figure which shows the relationship of.

The shock absorber 1 includes a reservoir tube 11, a pressure tube (inner tube) 12, a bush 13, an inner cover 14, a piston 15, a piston rod 16, a compression coil spring 18, an accumulator 19, an adjusting device 20, and the like. Has been done.

The reservoir tube 11 has a bottomed cylindrical shape having a bottom portion 11 a, and the inside thereof is sealed by a bush 13 to form an entire container for storing the pressure oil HY. The piston 15 slides on the inner peripheral surface of the pressure tube 12 mounted concentrically with the reservoir tube 11. The piston 15 is provided with packing 17 for preventing leakage with the pressure tube 12, and is closed when moving in the left direction (arrow M1 direction) in FIG. 1 and moving in the opposite direction. Sometimes there is a check valve that opens.

The inner cover 14 is provided at the position of the left end surface (bottom surface) of the pressure tube 12 so as not to leak from the pressure tube 12 and to be axially movable with respect to the pressure tube 12. There is.

A piston rod 16 is connected to the piston 15, and the piston rod 16 penetrates the bush 13 and projects to the outside. The compression coil spring 18 urges the piston 15 to the right and normally returns the piston 15, while urging the inner cover 14 to the left to bring the inner cover 14 into contact with an eccentric cam 21 described later. ing. The accumulator 19 absorbs the volume fluctuation in the chamber 31 due to the stroke position of the piston 15.

The pressure tube 12 is provided with a plurality of holes 41, 41, ... Which respectively form thin blade orifices and are arranged along the axial direction. Further, the inner cover 14 is also provided with a hole 42 that also forms a thin blade orifice.

The adjusting device 20 includes an eccentric cam 21 rotatably provided on the bottom 11 a of the reservoir tube 11, an adjusting knob 22 for rotating the eccentric cam 21 from the outside, and a lock screw 23 for fixing the adjusting knob 22. It consists of

The eccentric cam 21 is arranged such that the end surface of the cam plate 21a at the tip thereof faces the hole 42, and the opening area of the hole 42 is adjusted according to the rotational angle position of the cam plate 21a.

That is, as shown in FIG. 2, the cam plate 21a is rotated by rotating the adjusting knob 22, and the hole 42 is completely closed and completely opened. It is possible to adjust to any state in between. By this adjustment, the orifice area (or throttle amount) in the stroke after the piston 15 passes through all the holes 41, that is, in the rear effective stroke is adjusted.

That is, as shown in FIG. 3, when the piston 15 starts moving from the position shown in FIG. 1 in the direction of the arrow M1, the initial orifice area of all the holes 41 and 42 is Although based on the total opening area, the hole 41 is sequentially closed by the movement of the piston 15, and the orifice area is gradually reduced. The effective forward stroke is until it passes through all the holes 41. That is, in the front effective stroke, the orifice area changes according to the stroke position of the piston 15.

In the rear effective stroke, the orifice area is only the opening area of the hole 42 and can be adjusted from zero to the maximum area of the hole 42. It does not change depending on the stroke position of the piston 15.

Reference numeral 51 is a packing, and 52 and 53 are detent pins. Therefore, when the load collides with the piston rod 16 and the piston 15 moves in the direction of the arrow M1, the pressure oil HY in the chamber 31 flows out from the holes 41 and 42 to the outer chamber 32. At this time, the piston 15 receives resistance due to the back pressure generated in the chamber 31, and the kinetic energy of the load is absorbed.

By adjusting the eccentric cam 21, the orifice area in the rear effective stroke can be varied from zero to the maximum area of the hole 42, so that the outflow amount can be sufficiently reduced to increase the outflow resistance. Therefore, even if the mass or propulsive force of the load is large and the speed is small, it is possible to absorb the kinetic energy of the load and stop without impact, and it is necessary to increase the pressure receiving area of the piston as in the conventional case. In addition, the size of the device can be reduced.

Further, since the piston 15 is provided with the packing 17, the pressure oil HY in the chamber 31 does not leak from the gap between the piston 15 and the pressure tube 12 as in the conventional case, and particularly, the rear effective stroke. It is possible to realize a very small aperture amount. Therefore, the size of the device can be further reduced.

In the above-described embodiment, since the opening area of the hole 42 is changed by the eccentric cam 21, the influence of the fluctuation of the viscosity coefficient of the pressure oil HY is small, and the fluctuation of the cushioning effect due to the temperature change is small. Few.

Furthermore, since the structure of the shock absorber 1 is simple and a conventional metering tube that requires high-precision fitting with the pressure tube 12 is not required, cost reduction can be achieved. .

In the above-described embodiment, the kinetic energy when the load speed is high can be absorbed without excessive drag in the forward effective stroke of the plurality of holes 41.

In the above-described embodiment, the inner cover 14 is movable with respect to the pressure tube 12, and the back pressure in the compression coil spring 18 and the chamber 31 presses the eccentric cam 21. With such a structure, the inner cover 14 and the eccentric cam 21 are closely attached, and the hole 42 can be almost completely closed by the eccentric cam 21.

The shock absorber of the present invention can be applied as a shock absorber for absorbing shock or vibration, or as a hydrochecker for speed control during drilling.

That is, for example, in the case of a hydrochecker for controlling the feed rate of the drill, the front effective stroke can be used as the rapid feed section of the drill, and the rear effective stroke can be used as the cutting feed section of the drill. Further, the entire stroke can be used as the cutting feed section without providing the hole 41. That is, if the collision speed is zero, it is possible not to provide the effective front stroke.

As described above, by designing the orifice of the hole 41 so as to absorb the total of the kinetic energy of the load and the propulsive energy in the front effective stroke, it is possible to prevent the initial drag force from becoming excessive. In addition, by properly designing the hole 42 and the adjusting device 20, the required control speed can be obtained in the rear effective stroke.

In the above embodiment, the number of holes 41, 42 can be variously changed. Although the holes 41 and 42 are thin blade orifices, they may have other shapes such as a groove orifice. Instead of the adjustment knob 22 or together with the adjustment knob 22, the eccentric cam 21 may be rotated by a motor or the like. In addition, the structure, shape, size, material and the like of each part of the shock absorber 1 can be variously changed in accordance with the gist of the present invention.

[0037]

[Effect of device]

 According to the present invention, it is possible to reduce the cost by eliminating the need for a metering tube that requires high accuracy and precision, reduce the fluctuation of the buffering action due to temperature changes, and lead to the enlargement of the device due to insufficient throttling. There is no. Therefore, the performance of the shock absorber is not affected by the temperature, and a stable shock absorbing effect can be exhibited.

According to the second aspect of the invention, the inner cover and the eccentric cam are in close contact with each other with a simple structure, and the throttle hole can be almost completely closed by the eccentric cam. According to the invention of claim 3, the device can be further downsized.

[Brief description of drawings]

FIG. 1 is a sectional front view of a shock absorber according to the present invention.

FIG. 2 is a view for explaining the operation of the adjusting device of the shock absorber of FIG.

FIG. 3 is a diagram showing a relationship between a stroke of a shock absorber and an orifice area.

FIG. 4 is a sectional view showing an adjusting mechanism of a conventional hydraulic shock absorber.

[Explanation of symbols]

 1 shock absorber (fluid pressure shock absorber) 12 pressure tube 14 inner cover 15 piston 17 packing 21 eccentric cam (adjustment member) 22 adjustment knob 41 hole (throttle hole) 42 hole (throttle hole) HY pressure oil (fluid)

Claims (3)

[Scope of utility model registration request] 1. A piston moves in a pressure tube so that a fluid in the pressure tube flows out from a throttle hole, and a back pressure in the pressure tube based on an outflow resistance from the throttle hole provides a buffering action. In the fluid pressure type shock absorber made to exhibit, an inner cover for closing the inside of the pressure tube is provided at a position corresponding to the bottom surface of the pressure tube, and the inner cover is provided with at least one of the throttle holes. 1
Fluid pressure type shock absorber, wherein an adjusting member for adjusting the area of the opening of the throttle hole provided in the inner cover is provided so as to be operable from the outside. 2. The fluid pressure shock absorber according to claim 1, wherein the inner cover is provided so as to be movable in the axial direction with respect to the pressure tube, and the adjusting member is an axis line extending in the moving direction of the piston. A fluid pressure type shock absorber characterized by being an eccentric cam rotatable about a center. 3. The fluid pressure shock absorber according to claim 1, wherein the piston is provided with packing for sealing between the piston and the pressure tube. Pressure type shock absorber.