JPH0650018A - Hydraulic circuit for multistory parking device - Google Patents

Abstract

PURPOSE:To maintain the constant descending speed of a pallet, whether an automobile is loaded thereon or not, by providing a proportional valve, a reducing valve having an external drain type check and a compensation valve respectively between an actuator for elevating and lowering the pallet and a hydraulic source, and maintaining a constant differential pressure between the upstream and downstream sides of the proportional valve. CONSTITUTION:For causing a pallet 11 to descend, a proportional valve 18 is kept at a position (b) and a selector valve 19 is selected at a position (b). As a result, oil is returned from a hydraulic cylinder 14 to a tank 22 via a reducing valve 20, the selector valve 19 and the proportional valve 18 in order, thereby causing the pallet 11 to descend. In this case, the reducing valve 20 acts to keep pressure constant at the upstream side of the valve 18, and differential pressure becomes constant between the upstream and downstream sides of the valve 18. Thus, flow control is undertaken in compensated pressure state. According to this construction, the descending speed of the pallet 11 can be kept constant, whether an automobile is loaded thereon or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for a multilevel parking system.

[0002]

2. Description of the Related Art Conventionally, as a multilevel parking apparatus, as shown in FIG. 2, a pallet 1 on which an automobile is mounted is supported by columns 3 and 3 on a base 2 so as to be able to move up and down. It has been proposed to raise and lower with a hydraulic cylinder 4 (Japanese Patent Publication No. Sho 57-47585, Japanese Utility Model Publication No. 2-125).
155).

As shown in FIG. 3, the hydraulic cylinder 4 is
An on-off valve 6 is provided in the main line between the
When the opening / closing valve 6 is opened by operating the control box 7 and the hydraulic pressure is supplied from the pump 5 to the hydraulic cylinder 4, the pallet 1 is raised. Further, when the oil of the hydraulic cylinder 4 is returned to the tank 8 by the load of the pallet 1, the pallet 1 is lowered.

[0004]

However, in the above-mentioned conventional hydraulic circuit, when the pallet 1 is lowered, the pallet 1
There is a problem that the descending speed of the pallet 1 changes because the pressure of the oil discharged from the hydraulic cylinder 4 changes depending on whether the vehicle (load) is on or off the vehicle. Further, when the pallet 1 is raised, when the speed is switched from the high speed to the low speed, the hydraulic cylinder 4 self-excitedly vibrates due to the fluctuation of the hydraulic pressure, causing a so-called chattering.

Therefore, an object of the present invention is to provide a hydraulic circuit of a multi-story parking system which can smoothly raise and lower a pallet.

[0006]

In order to achieve the above object, the present invention, as illustrated in FIG. 1, includes a single-acting hydraulic actuator 14 for raising and lowering a pallet 11 on which an automobile A is placed and a hydraulic source 15. The proportional valve 18 whose opening is controlled according to the applied current is provided in the main line between the two, and the main line between the proportional valve 18 and the hydraulic actuator 14 is provided with The pressure reducing valve 20 with a check for controlling the pressure to a constant value is provided. The pressure reducing valve 20 is preferably an external drain type, and a pressure compensating valve 17 is preferably provided to control the differential pressure before and after the proportional valve to be constant when oil is supplied to the hydraulic actuator 14.

[0007]

According to the present invention, when the pallet 11 is lowered, the pressure on the upstream side of the proportional valve 18 is controlled to be constant by the pressure reducing valve 20, and the pressure on the downstream side of the proportional valve 18 is the tank pressure. The differential pressure between the upstream side and the downstream side of the proportional valve 18 becomes constant, and the flow rate can be controlled in a pressure-compensated state. The descending speed of the pallet 11 can be maintained constant regardless of the magnitude of the load. When the pallet 11 is raised, if the pressure reducing valve 20 is an external drain type, when the hydraulic actuator 14 is switched from high speed to low speed, or when the pressure reducing valve 20 is stopped, fluctuations in pressure on the hydraulic actuator 14 side cause pressure reducing valve 20.
Is relaxed by the external drain of. Therefore, the hydraulic actuator 14 is less likely to chatter. Further, when oil is supplied to the hydraulic actuator 14, if the pressure difference between the proportional valve 18 and the proportional valve 18 is controlled to be constant by the pressure compensating valve 17, the pallet 1
Accurate speed control is possible regardless of whether there is a car in 1.

[0008]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. As shown in FIG. 1, in this multilevel parking apparatus, a pallet 11 on which a car A is placed is supported by columns 13 on a base 12 so as to be able to move up and down. The pallet 11 includes a pulley 10a attached to a column 13 and a hydraulic cylinder 1
One end of a rope 10c wound around a pulley 10b attached to the No. 4 is connected, and the other end of the rope 10c is connected to an upper part of the support column 13. The pallet 11 is the pulley 1
0b is moved up and down by a single-acting hydraulic cylinder 14. That is, when oil is supplied to the hydraulic cylinder 14, the rod 14a moves downward and the pallet 11 is raised. Conversely, when oil is discharged from the hydraulic cylinder 14, the rod 14a moves upward and the pallet 11 moves. Can be lowered.

In the main line between the hydraulic cylinder 14 and the hydraulic source 15, a pressure reducing type pressure compensating valve 17, a direct acting proportional valve 18 and a switching valve are provided from the hydraulic source 15 side toward the hydraulic cylinder 14 side. 19, a pressure reducing valve 20 with a drain type check is sequentially provided. A controller 21 is connected to the proportional valve 18. Further, the hydraulic pressure source 1
The relief valve 16 is connected between the valve 5 and the pressure compensation valve 17.

When the pallet 11 is raised,
The switching valve 19 is switched to the position b, and the proportional valve 18 is set to an appropriate opening on the position a side by the controller 21. As a result, from the hydraulic pressure source 15 to the pressure compensation valve 17
-> Proportional valve 18-> Switching valve 19-> Oil is supplied to the hydraulic cylinder 14 through the check valve 20a of the pressure reducing valve with check 20, and the pallet 11 is raised.

The proportional valve 18 is controlled by the pressure compensating valve 17 in such a state that the differential pressure between the front and rear is constantly compensated.
The control of 1 controls the opening. Therefore, the flow rate is accurately controlled regardless of the magnitude of the load.

When the pallet 11 is raised, the proportional valve 18
As a result, when switching from high speed to low speed, the hydraulic pressure supplied to the hydraulic cylinder 14 fluctuates and chattering tends to occur, but the external drain type pressure reducing valve 20 operates to drain high pressure oil to the outside. Hydraulic cylinder 1
The fluctuation of the hydraulic pressure supplied to the hydraulic cylinder 4 is reduced, and the hydraulic cylinder 14 is less likely to chatter.

When the pallet 11 is raised to a predetermined raised position, the switching valve 19 is switched to the position c, and the proportional valve 1
8 is switched to the position c, the hydraulic cylinder 14 is stopped, and the pallet 11 is stopped. At this time, the pressure supplied to the hydraulic cylinder 14 tends to rise, but since the pressure reducing valve 20 is drained to the outside, chatter does not occur in the hydraulic cylinder.

On the other hand, when lowering the pallet 11, the proportional valve 18 is set to a predetermined opening on the position b side, and the switching valve 19 is switched to the position b. As a result, the load of the pallet 11 (when the automobile A is on the pallet 11, the load of the automobile A is also applied), the hydraulic cylinder 14 is passed through the pressure reducing valve 20 → the switching valve 19 → the proportional valve 18 to the tank. Oil is returned to 22 and pallet 11
Is lowered.

When the pallet 11 is lowered, the pressure reducing valve 20
Thus, the pressure on the upstream side of the proportional valve 18 is maintained constant. Since the pressure on the downstream side of the proportional valve 18 is the tank pressure, the differential pressure before and after the proportional valve 18 becomes constant, and the flow rate control is performed in a pressure-compensated state. Therefore, even if the load of only the pallet 11 or the load of the automobile A is applied thereto, the descending speed of the pallet 11 can be maintained constant.

Since the proportional valve 18 is of the direct acting type, not the pilot type, malfunctions due to clogging of dust are reduced. The pressure compensation valve is a pressure reducing type but may be a bypass type.

[0017]

As is apparent from the above description, in the hydraulic circuit of the multi-level parking apparatus according to the first aspect of the present invention, the oil discharged from the single-acting actuator through the proportional valve to the tank when the pallet is lowered. The pressure on the upstream side of the proportional valve can be controlled to be constant by the pressure reducing valve with check. Therefore, the descending speed of the pallet can be made constant regardless of the presence or absence of a vehicle on the pallet. Further, since the hydraulic circuit of the multi-storied parking apparatus according to claim 2 uses the external drain type pressure reducing valve, the external drain prevents the hydraulic actuator from chattering when the hydraulic actuator is switched from high speed to low speed or when stopped. Become. In addition, the pressure compensating valve controls the differential pressure before and after the proportional valve to a constant value, so the flow rate can be accurately controlled regardless of the load of the hydraulic actuator, and the pallet can be controlled regardless of the presence or absence of a vehicle on the pallet. Accurate speed control is possible.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a multilevel parking apparatus according to the present invention.

FIG. 2 is a perspective view of a conventional multi-level parking device.

FIG. 3 Conventional hydraulic circuit diagram

[Explanation of symbols]

11 ... Pallet, 14 ... Hydraulic cylinder, 15 ... Hydraulic source, 18 ... Proportional valve, 20 ... External drain type pressure reducing valve with check.

Claims (2)

[Claims] 1. A pallet (11) for carrying a car (A)
A proportional valve (18) whose opening is controlled according to an applied current is provided in a main line between a single-acting hydraulic actuator (14) for moving up and down and a hydraulic source (15). In the main line between the hydraulic actuator (14) and the hydraulic actuator (14), there is provided a check pressure reducing valve (20) for controlling the pressure of the oil supplied to the proportional valve (18) to a constant level. The hydraulic circuit of the device. 2. The pressure reducing valve (20) is an external drain type, and is a pressure compensator for controlling a differential pressure before and after the proportional valve (18) to be constant when oil is supplied to the hydraulic actuator (14). 2. A valve (17) provided, characterized in that
The hydraulic circuit of the multi-level parking device described in.