JPH0131762Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses a sensor to detect when the piston approaches the end of its stroke, and a flow control device to automatically reduce the amount of fluid supplied to the cylinder so that the piston reaches its stroke end. The present invention relates to an improvement in a fluid pressure cylinder drive device configured to relieve shock when the stroke end is reached, and in particular to a flow rate control device.

Conventionally, in configuring the above-mentioned control device, for example, a third
As shown in the figure, a two-position flow control valve 13 that can be switched between a no-load state and a throttle state is provided in the supply path from the metering pump 3, and based on information from the sensor 12, the piston 1b reaches the stroke end. The controller 14 is configured to automatically switch the flow rate control valve 13 from the no-load state to the throttle state when the flow rate control valve 13 approaches .

However, since a sudden and large change in flow rate occurs when the flow control valve 13 is switched, for example, fluctuations in the buffer function increase due to changes in the viscosity of the oil, and abnormal noises may occur due to an increase in the viscosity of the oil. There were various drawbacks, such as an increase in oil temperature and a noticeable power loss due to increased flow resistance, and a loss of smooth operation of the cylinder 1.

The purpose of the present invention is to eliminate the above-mentioned drawbacks and to enable rapid reciprocating of the piston of the fluid pressure cylinder.

The characteristic configuration of the present invention for achieving the above object is that the pump is of a variable displacement type, and the operating valve of the fluid pressure cylinder is located in an operating position to drive the fluid pressure cylinder in either forward or reverse direction. A position detection sensor is provided to detect whether or not the
Information from the stroke sensor detects that the piston of the fluid pressure cylinder has come to a position near the stroke end, and detects that the operating valve of the fluid pressure cylinder is in an operating position in the direction of moving the piston closer to the stroke end. The present invention is characterized in that an operating device is provided that gradually reduces the discharge amount of the pump based on both information and information from the position detection sensor.

In other words, as the piston approaches the end of its stroke, the discharge amount of the variable displacement pump itself is reduced, so even if the viscosity of the oil changes, it is possible to maintain an almost constant good buffering function. Even if the viscosity of the oil increases, the occurrence of abnormal noise can be effectively suppressed and the cylinder can operate smoothly.Furthermore, since the discharge capacity of the pump itself is reduced, it is possible to reduce the amount of fluid supplied. As a result, the load on the pump is reduced, improving power efficiency, and since there is no increase in fluid pressure, inconvenient situations such as increases in oil temperature can be eliminated, resulting in improvements in terms of operation, buffer function, and power efficiency. In either case, it has become possible to provide a hydraulic cylinder drive device that is superior to the conventional one.

Moreover, by looking at the AND condition of the detection result that the operating valve of the fluid pressure cylinder is in the operating position in the direction of moving the piston closer to the stroke end, and the detection result that the piston is located near the stroke end, the pump discharge Therefore, when the piston is at the stroke end and the operation valve of the fluid pressure cylinder is switched from the neutral operation position to the reverse operation side, the AND condition is broken and the pump discharge amount immediately decreases. There is an advantage that the piston can be switched to the increasing direction and the piston can be quickly moved in the reverse direction.

Next, an example will be described.

As shown in Fig. 1, a variable displacement pump 3 is connected to a hydraulic cylinder 1 installed in construction machinery, agricultural machinery, and various other devices via an operating valve 2 that drives the cylinder in forward and reverse directions and stops it. , the expansion and contraction speed of the cylinder 1 can be adjusted by changing the discharge amount of the pump 3.

A ring-shaped proximity switch 4 is attached to the tube 1a of the cylinder 1 so as to surround the outer circumferential surface of the tube 1a, and as the piston 1b approaches the proximity switch 4, the magnetic field of the proximity switch 4 is changed. The arrangement is such that an electric signal is sent from the proximity switch 4 to the controller 5 to notify that the piston 1b has approached the end of its stroke based on the change in the magnetic field.

Further, a position detection sensor 9 is provided to detect whether the operation valve 2 is in the neutral position or the operation position, and when the position detection sensor 9 detects that the operation valve 2 is in the operation position, the controller The configuration is such that an electrical signal is sent to 5.

The controller 5 is configured to generate an electric signal when an AND condition between the proximity switch 4 and the position detection sensor 9 is satisfied.

A spring recovery type single-acting cylinder 6 for changing the discharge amount of the pump 3 is provided, and an electromagnetic flow path automatically operated by the controller 5 is provided between the cylinder 6 and an auxiliary pump 7 that drives it. A switching valve 8 is provided, and when the proximity switch 4 notifies that the piston 1b approaches the stroke end, the controller 5 drives the single-acting cylinder 6 with the auxiliary pump 7 to change the discharge amount of the pump 3. The flow path switching valve 8 is configured to be automatically operated to gradually reduce the amount of water.

Next, an example will be described.

To detect whether the piston 1b is near the stroke end, for example, as shown in FIG. 2, the movable part 12a of a variable resistance type or differential transformer type detector 12 is linked to the piston 1b. Various configuration changes are possible, such as having the controller 5 perform position detection based on whether the information value from the detector 12 is within the set range. Collectively called.

In order to reduce the discharge amount of the pump 3, various configuration changes can be made, such as interlocking a drive device such as an electric motor or an air cylinder with the pump discharge amount adjusting operation section and having it automatically operated by the controller 5. The configuration for adjusting the discharge amount is collectively referred to as the operating device 6.

The specific configuration for linking the sensors 4, 12 and the operating device 6 can be easily modified in various ways from the control technology perspective, and can be easily changed depending on the target cylinder 1.
may be an air cylinder or the like, or any fluid pressure cylinder.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

The drawings show an embodiment of the hydraulic cylinder drive device according to the present invention, and FIG. 1 is a hydraulic and control circuit diagram;
FIG. 2 is a hydraulic pressure and control circuit diagram showing another embodiment, and FIG. 3 is a hydraulic pressure and control circuit diagram showing a conventional example. DESCRIPTION OF SYMBOLS 1... Cylinder, 1b... Piston, 2... Control valve, 3... Pump, 4, 12... Stroke sensor, 6... Operating device, 9... Control valve position detection sensor.

Claims (1)

[Scope of utility model registration request] A stroke sensor 4 or 12 is provided to detect whether the piston 1b of the fluid pressure cylinder 1 is near the stroke end, and the amount of fluid supplied from the pump 3 to the cylinder 1 is determined based on information from the stroke sensor 4 or 12. This is a fluid pressure cylinder drive device equipped with a flow rate control device for automatically reducing the flow rate when the piston 1b approaches the end of its stroke. In addition, a position detection sensor 9 is provided to detect whether or not the operation valve 2 of the fluid pressure cylinder 1 is in an operation position for driving the fluid pressure cylinder 1 in either the forward or reverse direction. information from the stroke sensor 4 or 12 that detects that the piston 1b has come to a position near the stroke end, and that the operation valve 2 of the fluid pressure cylinder 1 is in an operation position in the direction of moving the piston 1b closer to the stroke end. A driving device for a fluid pressure cylinder, characterized in that an operation position 6 is provided for gradually decreasing the discharge amount of the pump 3 based on both information from the position detection sensor 9 that detects the above.