JPH0651559B2 - Two-post lift safety device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device such as an automobile maintenance lift, and more particularly to a safety device for a two-post type lift constructed so that two columns are lifted and lowered by two hydraulic cylinders. Is.

[0002]

2. Description of the Related Art FIG. 6 is a schematic view of a two-post type vehicle maintenance lift, FIG. 7 is a hydraulic circuit diagram of a conventional two-post type vehicle maintenance lift, and FIG. 8 is a safety mechanism of the two-column type vehicle maintenance lift. It is a schematic diagram showing. As shown in FIG. 6, generally, in a two-post type vehicle maintenance lift, it is an important issue to raise and lower the two columns 2 in synchronism with each other so that there is no difference in height. 41 is tilted and very dangerous. In view of this point, the technique shown in FIG. 7 has been conventionally proposed. In FIG. 7, reference numerals 12 and 13 denote driving and driven hydraulic cylinders for moving the columns 2 up and down, and 16 denotes a hydraulic unit for driving the hydraulic cylinders 12 and 13. In this hydraulic unit 16, the check valve 2 is attached to the hydraulic pump 27.
Hydraulic cylinders 12 and 13 are connected in series via 8. Further, the hydraulic unit 16 is provided with a relief valve 29 and a switching valve 20, and the hydraulic cylinders 12 and 13 are raised at the A position of the switching valve 20 and lowered at the B position. According to this, since the two hydraulic cylinders 12 and 13 are connected in series to the single hydraulic pump 27, in the normal state, the two columns 2 can be raised and lowered in synchronization with each other. .

[0003]

However, according to the conventional two-post type vehicle maintenance lift, when the driven hydraulic cylinder 13 is lowered or stopped after being delayed,
In some cases, the drive hydraulic cylinder 12 was lowered first because the two hydraulic cylinders 12 and 13 were out of synchronization. As a cause of the driven hydraulic cylinder 13 descending with a delay, troubles of the safety mechanism can be pointed out. In this type of hydraulic lift, a safety mechanism including a rack 4 and pawls 5 as shown in FIG. 8 is provided, and the rack 4 and the pawls 5 are provided when oil leaks from the packing in the hydraulic unit. Prevents the pillar 2 from falling naturally by engaging with
Upon lowering, the hydraulic cylinders 12 and 13 are operated after the pawl 5 is completely disengaged from the rack 4. However, this safety mechanism uses each hydraulic cylinder 12,
Since the claws 5 of the driven hydraulic cylinder 13 cannot be disengaged in synchronism with each other when they are lowered, that is, the claws 5 of the driven hydraulic cylinder 13 are engaged with the rack 4 and cannot be lowered. There was a possibility that the claw 5 of 12 would come off and this side would descend first.

As a measure to prevent such an unsynchronized operation, conventionally, the driving and driven side claws 5 are connected via a mechanical means such as a link, or the position of the claw 5 is detected by an electric means such as a limit switch. However, a method has been proposed in which the claw 5 is controlled to stop descending when it does not operate.
However, when a mechanical means is used, a rigid and complicated mechanism is required, which causes a problem of cost increase. Also, in the case of electrical means, the ignition source such as a limit switch is attached to the lift body, that is, the part that comes into contact with the outside air.Therefore, if the lift is installed in an explosion hazardous area, special protection measures are required. there were. Besides,
Since all of them are countermeasures against the trouble of the claw 5, they are vulnerable to the unsynchronized operation due to other causes.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a safety device for a two-pillar lift capable of accurately detecting an unsynchronized operation of two hydraulic cylinders by a simple and safe means, thereby improving safety. It is in.

[0006]

In order to solve the above-mentioned problems, a safety device for a two-pillar lift according to the present invention comprises two columns for supporting a loading platform and two hydraulic pressures for raising and lowering each column. It includes a cylinder, a hydraulic unit for synchronously driving each hydraulic cylinder, and a flow rate sensor incorporated in the hydraulic unit for detecting the flow rate of pressure oil and generating a stop signal when the hydraulic cylinders are out of synchronization.

[0007]

According to the two-pillar lift safety device of the present invention,
The flow rate sensor detects the flow rate of pressure oil and generates a stop signal when the two hydraulic cylinders are out of synchronism, so no matter what trouble occurs in the drive system of the column, it responds appropriately to the hydraulic pressure. The cylinder operation is stopped. As a result, the loading platform is always held horizontally, and safety is improved. Also, since the flow rate sensor is built into the hydraulic unit, unlike the case where a detection device is installed on the lift body side, there is no concern of becoming an ignition source, the lift can be safely operated even in an explosion hazardous area, and the flow rate sensor is Can be easily installed in a relatively large space. Moreover, the use of this flow rate sensor eliminates the need for a detection device related to the safety mechanism, which can contribute to cost reduction.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a hydraulic circuit diagram of a two-post type vehicle maintenance lift showing an embodiment of the present invention, and FIG. 2 is a front view showing the entire two-column type vehicle maintenance lift. In FIG. 2, 1 is a machine frame of an automobile maintenance lift, 35 is a guide provided in the machine frame 1, 2 is two columns supported by the guide 35 so as to be able to move up and down, and 3 is fixed to an upper end of the column 2. Mounted vehicle mount, 12 is a drive hydraulic cylinder for moving up and down one of the columns 2,
13 is a driven hydraulic cylinder that raises and lowers the other column 2, 16
Is a hydraulic unit that drives each hydraulic cylinder 12, 13,
Reference numeral 37 is an operation switch connected to the hydraulic unit 16.

As shown in FIG. 1, the drive hydraulic cylinder 12
The driven hydraulic cylinder 13 and the driven hydraulic cylinder 13 are each of a backward movement type, and are connected in series via a pipe line 14. The hydraulic unit 16 includes a pressure oil supply line 17 and a rising line 18
A switching valve 20 is provided to switch between the lowering line 19 and the lowering line 19. A pilot operated valve 21, a flow control valve 22, and a check valve 23 having a check function are arranged on the ascending pipeline 18. The pilot operated valve 21 is connected to the descending pipeline 19 via a pilot pipeline 24. A flow rate sensor 38 that detects the flow rate of the pressure oil flowing therethrough and that generates a stop signal when the hydraulic cylinders 12 and 13 are out of synchronization is provided on the downcomer pipe 19. 27 is a hydraulic pump, 39 is a motor for driving the hydraulic pump 27, 28 is a check valve, 29
Is a relief valve and 30 is a tank.

Next, the operation of the two-column type vehicle maintenance lift constructed as described above will be described. Operation switch 3
When the up button of 7 is pressed, the hydraulic pump 27 is rotated by the motor 39, the switching valve 20 is switched to the A position, and the pressure oil supply line 17 is connected to the up line 18. The pressure oil discharged from the hydraulic pump 27 is supplied to the drive hydraulic cylinder 12 via the pilot operation valve 21 and the check valve 23.
As a result, the piston 12a of the drive hydraulic cylinder 12 is raised, and the piston 13a of the driven hydraulic cylinder 13 is also raised by the discharge oil of the drive hydraulic cylinder 12. Then, the oil discharged from the driven hydraulic cylinder 13 returns to the tank 30 via the flow rate sensor 38 and the descending conduit 19. At this time, the flow rate sensor 38 is not functioning.

When the down button of the operation switch 37 is pressed,
The switching valve 20 is switched to the B position, the pressure oil supply pipe line 17 is connected to the descending pipe line 19, and the pressure oil discharged from the hydraulic pump 27 is supplied to the driven hydraulic cylinder 13 through the flow rate sensor 38 and its piston. 13a is pushed down, and the piston 12a of the drive hydraulic cylinder 12 is also pushed down by the oil discharged from the driven hydraulic cylinder 13. At this time, the flow rate sensor 38 is functioning, but since the flow rate of the pressure oil flowing through the descending conduit 19 is constant, no detection signal is output and the descending operation is continued. Then, the discharge oil of the drive hydraulic cylinder 12 returns to the tank 30 through the flow rate control valve 22, the pilot operation valve 21 opened by the pilot pressure of the descending conduit 19 and the ascending conduit 18.

By the way, when either the driven hydraulic cylinder 13 or the drive hydraulic cylinder 12 is out of synchronism with the other during the lowering operation, the lowering speed of the piston 13a of the driven hydraulic cylinder 13 decreases, The flow rate of the pressure oil flowing through the descending conduit 19 becomes smaller than that in normal times. Therefore, the flow sensor 38 outputs a stop signal, and in response to this, a relay circuit (not shown) is activated to cut off the electric circuit for lowering operation. As a result, each hydraulic cylinder 1
The operation of Nos. 2 and 13 is stopped, and the unsynchronized lowering of the column 2 is prevented in advance. Since the hydraulic cylinders 12 and 13 are connected in series, there is no possibility that their synchronization will be lost when moving up. Therefore, according to this embodiment, the hydraulic cylinders 12 and 13 are moving up and down. , 13
It is possible to prevent the unsynchronized operation of the.

As described above, according to the two-post type vehicle maintenance lift of this embodiment, the flow rate sensor 38 detects the flow rate of the pressure oil and outputs a stop signal when the hydraulic cylinders 12 and 13 are out of synchronization. Therefore, no matter what kind of trouble occurs in the drive system of the column 2, the hydraulic cylinders 12 and 13 can be stopped in response to the trouble accurately, thereby keeping the vehicle-mounted base 3 always horizontal, The safety can be improved. Further, since the flow rate sensor 38 is incorporated inside the hydraulic unit 16, unlike the case where it is provided on the lift body side,
There is no fear of becoming a source of ignition, it can be safely applied to lifts that are installed in explosion-hazardous areas, and it is far more advantageous in terms of installation space than the lift body side. Moreover, use of the flow rate sensor 38 eliminates the need for a detection device related to the claw 5 of the safety mechanism, which contributes to cost reduction.

In the above embodiment, the flow rate sensor 38 is provided on the descending conduit 19, but the flow rate sensor 38 may be provided on the discharge side of the relief valve 29 as shown in FIG. Good. When pressure oil stops in the drive hydraulic cylinder 12 or the driven hydraulic cylinder 13 due to a trouble of the pawl 5 in the safety mechanism, the amount of oil returning from the relief valve 29 to the tank 30 increases. Therefore, if the flow rate sensor 38 is provided on the discharge side of the relief valve 29 and the discharge flow rate is detected, the unsynchronized operation of the hydraulic cylinders 12 and 13 can be accurately detected as in the above-described embodiment.

Further, the two-post type automobile maintenance lift of the above-mentioned embodiment is constructed by connecting the return-acting hydraulic cylinders 12 and 13 in series, but as shown in FIG. It is also possible to embody the present invention by applying the present invention to a two-post type lift formed by connecting the hydraulic cylinders 32 and 33 of the shape in parallel to the hydraulic pump 27. In this case, each hydraulic cylinder 32, 3
If the flow rate sensors 38 are provided on the inflow conduits 3 respectively,
The unsynchronized operation of these two single-acting hydraulic cylinders 32, 33 can be accurately detected. Further, as shown in FIG. 5, the drive hydraulic cylinder 12 is of the backward type and the driven hydraulic cylinder 1
A single-acting type is used as 3 and these are hydraulic pump 2
The present invention can also be applied to a two-pillar lift that is connected to 7 in series. In this case, each hydraulic cylinder 12, 1
A flow sensor 38 can be provided on the conduit 14 connecting the three. In addition, the present invention is not limited to a lift for automobile maintenance, and is applied to various two-post type lifts configured to vertically move two columns in synchronization with two hydraulic cylinders. It is also possible to change and embody the configuration of each part as appropriate without departing from the spirit of the above.

[0016]

As described above in detail, according to the present invention, since the flow rate sensor detects the flow rate of the pressure oil and outputs the stop signal, any trouble occurs in the drive system of the column. However, in response to this, the operation of the hydraulic cylinder can be stopped, and thus the loading platform can be kept horizontally at all times to improve safety, and by incorporating the flow rate sensor inside the hydraulic unit, there is a danger of explosion. However, the lift can be safely operated, the flow rate sensor can be easily mounted in a relatively large space, and the detection device related to the safety mechanism is not required, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram of a two-post type vehicle maintenance lift showing an embodiment of the present invention.

FIG. 2 is a front view showing the entire two-pillar vehicle maintenance lift.

FIG. 3 is a hydraulic circuit diagram showing another embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram showing an application example of the present invention.

FIG. 5 is a hydraulic circuit diagram showing another application example of the present invention.

FIG. 6 is a schematic view of a two-pillar vehicle maintenance lift.

FIG. 7 is a hydraulic circuit diagram of a conventional two-post type vehicle maintenance lift.

FIG. 8 is a schematic view showing a safety mechanism of a two-pillar vehicle maintenance lift.

[Explanation of symbols]

1 ・ ・ Machine frame 2 ・ ・ Posts 3 ・ ・ Vehicle base 4 ・ ・ Rack 5 ・ ・ Pawls 12 ・ ・ Drive hydraulic cylinders 13 ・ ・ Driven hydraulic cylinders 14 ・ ・ Pipe lines 16 ・ ・Hydraulic unit, 17 ... Pressure oil supply line, 18 ... Ascent line, 19 ...
・ Descent line, 20 ・ ・ Switching valve, 21 ・ ・ Pilot operated valve, 22 ・ ・ Flow control valve, 23 ・ ・ Check valve, 24 ・ ・ Pilot line, 27 ・ ・ Hydraulic pump, 28 ・ ・ Check valve,
29 ... Relief valve, 30 ... Tank, 32, 33 ...
Hydraulic cylinder, 35 ... Guide, 37 ... Operation switch, 38 ... Flow rate sensor, 39 ... Motor.

Claims (1)

[Claims] 1. A column for supporting a loading platform, two hydraulic cylinders for raising and lowering each column, a hydraulic unit for synchronously driving the hydraulic cylinders, a hydraulic unit incorporated into the hydraulic unit, and a flow rate of pressure oil. A safety device for a two-pillar lift, comprising: a flow rate sensor that detects when the hydraulic cylinders are out of synchronization and generates a stop signal when the hydraulic cylinders are out of synchronization.