JPS6252206A - Counterbalance valve in hydraulic elevating device - Google Patents

Abstract

PURPOSE:To prevent a failure and a lowering of life of an upstream circuit apparatus and to promote energy saving by providing means for decreasing back pressure on an upstream counter balance valve. CONSTITUTION:A hydraulic actuator 5 provided with a counterbalance valve 6 and another downstream hydraulic actuator 7 are connected in series to a hydraulic pump 1 by center by-pass type directional control valves 2, 3, and a back pressure chamber 28 of the upstream counterbalance valve 6 is connected to a drain passage 29. Thus, upstream circuit pressure can be decreased to prevent a failure and a lowering of life of an upstream circuit apparatus. As pump driving power can be reduced, and further descending position energy of an upstream load is used for driving force of the downstream hydraulic actuator, energy can be effectively used.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a counterbalance valve for a hydraulic lifting device or a hydraulic drive device including a hydraulic lifting device used in ships, construction machines, and other lifting machines. .

[Conventional technology]

In general, this type of hydraulic lifting device or a hydraulic drive device including a hydraulic lifting device often has a plurality of hydraulic actuators connected in series to a common pump.

For example, in the conventional device shown in FIG. 4, a hydraulic pump 1 is connected to a tank 4 via a center bypass type directional control valve 2.3, and a hydraulic motor 5 is connected to the directional control valve 2 via a counterbalance valve 6. A hydraulic motor 7 is connected to the directional control valve 3 via a counterbalance valve 8.

The counterbalance valve 6.8 opposes the hydraulic pressure in the flow paths 20, 25 via the spool 27 with the set pressure by the spring 26 and the back pressure of the counterbalance valves 6, 8, that is, the oil pressure in the flow paths 17, 22. For example, as shown in Figure 5,
The counterbalance valve described in Publication No. 251 applies a spring 26 via a spool 27 to the external pilot pressure that leads to the C port.
The hydraulic pressure in the flow path 17 communicating with the spring chamber 55 housing the spring 26 through the small hole 56 is opposed.

In FIG. 4, if only the directional control valve 2 is switched to position A or B, pressure oil from the hydraulic pump 1 is supplied to the hydraulic motor 5 from the flow path 17, the check valve 18, the flow path 19, or the flow path 20, The return oil is returned to the tank 4 from the flow path 20 or 19, the counterbalance valve 6, and the flow path 17 through the directional switching valve 2, the flow path 15, the directional switching valve 3, and the return flow path 16, and is returned to the tank 4 only to the hydraulic motor 5. Drive. Also, when only the directional control valve 3 is switched to position A or B, the pressure oil from the hydraulic pump 1 flows through the flow path 1.
4. The oil is supplied to the hydraulic motor 7 from the flow path 22, the check valve 23, the flow path 24, or the flow path 25 through the directional control valve 2, the flow path 15, and the directional control valve 3, and the return oil is supplied to the hydraulic motor 7 through the flow path 25 or the flow path. 24
, a counterbalance valve 8, a directional control valve 3 passing through a flow path 22
, through the return flow path 21 to the tank 4, and only the hydraulic motor 7 is driven.

Next, when the directional control valve 2 is switched to position B and the directional control valve 3 is switched to position A, the pressure oil from the hydraulic pump 1 is transferred to the flow path 14, the directional control valve 2, the flow path 20, and the hydraulic motor 5.
, flow path 19, counterbalance valve 6, flow path 17, directional switching valve 2, flow path 15, directional switching valve 3, flow path 22, check valve 23, flow path 24, hydraulic motor 7, flow path 25, directional switching It passes through the valve 3 and returns to the tank 4 via the return flow path 21. That is, the hydraulic motors 5 and 7 are connected in series to the pump 1 and driven together, the hydraulic motor 5 unloads the load 9, and the hydraulic motor 7 lowers the load 9.
hoists a load.

[Problem that the invention seeks to solve]

In the conventional device, the hydraulic motor 5 on the upstream side lowers a load equivalent to 140 kg f lct& at the effective pressure of the lowering brake, and the hydraulic motor 7 on the downstream side lowers the load equivalent to 140 kg at the effective pressure of the lowering brake.
Assuming that a load equivalent to f/c+A is being wound and unloaded, if the pressure in the flow path 25 is 10 kg f/cJ, the pressure in each flow path will be as follows. That is, the pressure in the flow paths 24 and 22.15°17 is 10+140-150 (kgf/cJ
), if the pressure required to open the counterbalance valve 6 against the spring 26 is 30 kgf/c+J, then the pressure in the flow path 20 is 150+30=180 <kgf/C>)
, the pressure in the flow path 19 is 180+140=320 (kgf
/cJ).

In this case, the pressure required for the hydraulic pump 1 is 180 kgf/cJ, which is the same as the pressure in the flow path 20, and the pump driving power becomes large, so that the potential energy of the load on the upstream side is not utilized. Moreover, because the hydraulic pressure in the upstream circuit is high, the hydraulic motor 5
Therefore, the present invention reduces the upstream circuit pressure by simple means, thereby preventing failures and shortening the life of the upstream circuit equipment. The purpose of the present invention is to reduce pump drive power and utilize the lowering potential energy of the load on the upstream side as the power to hoist the load on the downstream side, thereby saving energy.

[Means for solving problems]

The structure of the present invention for achieving the above object will be explained using FIGS. 1 to 3 corresponding to embodiments. A hydraulic actuator 5 equipped with a counterbalance valve 6 and another hydraulic actuator 7 downstream thereof are connected in series to the hydraulic pump 1 by a center bypass type directional control valve 2.3, and can be driven simultaneously. In a hydraulic drive device including a lifting device or a hydraulic lifting device, a counterbalance valve 6 on the upstream side is provided with means for reducing back pressure. For example, all of the back pressure chambers 28 of the counterbalance valve 6 or only one of the back pressure chambers 28.42 is connected to the drain passage 29.

[For production]

In FIG. 1, when the directional control valve 2 is switched to position B and the directional control valve 3 is switched to position A, the pressure oil from the hydraulic pump 1 is transferred to the flow path 14, the directional control valve 2, the flow path 20, the hydraulic actuator 5, Flow path 19, counterbalance valve 6, flow path 17, directional switching valve 2, flow path 15, directional switching valve 3, flow path 22, check valve 23, flow path 24, hydraulic actuator 7, flow path 25
, the directional switching valve 3, and the return passage 21 to the tank 4, the hydraulic actuator 5 lowers the load 9, and the hydraulic actuator 7 hoists the load.

In this hoisting and lowering operation, similarly to the conventional device, the hydraulic actuator 5 is operated at a lowering brake effective pressure of 14
A load equivalent to 0 kgf/cn+ is lowered, and the hydraulic motor 7 on the downstream side has an effective pressure of 14. If a load equivalent to 10 kg f lca is being hoisted, the pressure in the flow path 25 is 10 kg f lca.
/cta, the pressure in channels 24, 22, 15.17 is 1
0+140-150 (kgf/cJ). Also, if the pressure required to open the counterbalance valve 6 against the spring 26 is 30 kg f / cJ, and the back pressure of the counterbalance valve 6 is zero, the pressure in the flow path 20 is 0 + 30 = 30.
(kgf/crA), the pressure in the flow path 19 is 30+140
=170 (kgf/cJ). Furthermore, if the pressure in the flow path 17 acts on 1/3 of the cross-sectional area of the spool of the counterbalance valve 6, the pressure in the flow path 20 will be 150X1/
3+30=80 (kgf/aa), and the pressure in the flow path 19 is 86+140=220<kgf/cJ).

Therefore, the pressure required for the hydraulic pump 1 is 30 to 80 kg f /ct & because the hydraulic pump 1 is connected to the flow path 20 via the directional control valve 2, and the pressure required for the same load is 30 to 80 kg f /ct&.
The same lowering and hoisting operations as the conventional device can be performed at a pressure 100 to 150 kgf/cJ lower than that of the conventional device under the same operating conditions, which is 180 kgf/cJ. In addition, the pressure in the flow path 19 was also 320 kgf in the conventional device.
/cJ can be significantly reduced to 170 to 220 kgf/ci.

〔Example〕

Embodiments of the present invention will be described with reference to FIGS. 1 to 3. In FIG. 1, a hydraulic pump 1 is connected to a tank 4 via a center bypass type directional valve 2.3.
is connected to the hydraulic motor 5 via the counterbalance valve 6, and the directional control valve 3 is connected to the hydraulic motor 7 via the counterbalance valve 8.
is connected to.

Although not shown in the diagram, the hydraulic motor 5
Similarly, a winch drum is connected to which the load is attached.

11, 12, and 13 are relief valves, respectively.

The above configuration is similar to the conventional device shown in FIG. or,
The counterbalance valve 8 uses the set pressure by the spring 26 and the oil pressure led from the flow path 22 to oppose the oil pressure in the flow path 25 via the spool 27, so it is similar to the counterbalance valve 8 of the conventional device. It is the composition. On the other hand, the counterbalance valve 6 opens the spring chamber 28, which is a back pressure chamber, to the drain passage 29.

FIG. 2 shows a specific example of the configuration of the counterbalance valve 6. As shown in FIG.

In the figure, a through hole 32 communicating with the flow path 20 is provided at one end of the spool 27 which is fitted into the casing 31 so as to be movable forward and backward.
, 33, and a throttle hole 34 is provided, and this throttle hole 34 is connected to a liquid chamber 35 facing the spool end. On the other hand, spool 27
The spring chamber 28, which is a back pressure chamber whose other end faces, communicates with the drain passage 29 through the through hole 39, so that the spring chamber 28 is connected to the drain passage 29 from the flow passage 17 through the gap between the spool insertion hole 38 and the spool 27. The hydraulic oil accumulated in the drain passage 29 is discharged through the drain passage 29.

Therefore, the back pressure in the spring chamber 28 is zero and only the spring 26 opposes the pressure in the flow path 20 via the spool 27.

Another embodiment shown in FIG. 3 is one in which a damping mechanism 40 is added to the configuration shown in FIG.
8 and a damping chamber 42 of a damping mechanism 40,
The spring chamber 28 communicates with the drain passage 29, and the damping chamber 42 on which the pressure of the flow passage 17 acts has a cross-sectional area of 1/3 of the cross-sectional area of the spool 27, so the back pressure applied to the spool is 1/3 of that of the conventional device. becomes. In this example, the spool 27
Instead of creating some back pressure, a damping function is added.

The damping mechanism 40 includes a diving chamber 42 in which a piston 41 is inserted into the end of the spool 27 on the spring 26 side. The damping chamber 42 is in contact with the flow passage 17 via the through hole 46, the check valve 47 that allows fluid flow only into the damping chamber 42, the passage 48, 49, and the throttle hole 50, the annular groove of the spool 27. It communicates with the flow path 17 via 51. With this configuration, when the spool 27 moves in the valve opening direction (rightward in the figure), the throttle hole 50 throttles the pressure oil from the damping chamber 42, so a damping action of the spool is obtained, and a sudden decrease in flow rate, sudden increase in load, etc. When moving in the valve closing direction, the check valve 47 opens, the damping chamber 42 and the flow path 17 communicate with each other, and the valve is quickly closed.

In FIG. 1, when the directional switching valve 2 is switched to position B and the directional switching valve 3 is switched to position A, in order to lower the load 9 by the hydraulic motor 5 and hoist the load by the hydraulic motor 7 at the same time, the hydraulic pump 1 The oil discharged from the flow path 14 and the directional control valve 2
, flow path 20, hydraulic motor 5, flow path I9, counterbalance valve 6, flow path 17, directional switching valve 2, flow path 15, directional switching valve 3, flow path 22, check valve 23, flow path 24, hydraulic motor 7, the flow is returned to the tank 4 via the flow path 25, the direction switching valve 3, and the return flow path 21, the hydraulic motor 5 is driven in the load lowering direction, and the hydraulic motor 7 is driven in the load hoisting direction.

In this lowering and hoisting operation, the hydraulic motor 5 has a lowering brake effective pressure of 140 kg, similar to the conventional device described above.
f/cA, and the hydraulic motor 7 is hoisting a load equivalent to an effective pressure of 140 kgf/cil. If the pressure in the flow path 25 is 10 kgf/cJ, the flow paths 24, 22, 15 .17 pressure is 10+140-150
(k+rf/CJ), the pressure required to open the counterbalance valve 6 against the spring 26 is 30kgf/
cA, the pressure in the flow path 20 is 3 Q kg f /cJ in the counterbalance valve 6 where no back pressure acts on the spring side end of the spool 27 as shown in FIG. 2, and the pressure in the flow path 1
The pressure at point 9 is 30+140=170 (kgf/cJ). Further, as shown in FIG. 3, in the counterbalance valve 6 having the damping chamber 42 whose cross-sectional area is 1/3 of the spool cross-sectional area, the pressure in the flow path 20 is 30+150X1/3=
80 (kgf/c+It), and the pressure in the flow path 19 is 80+140=220 (kgf/ci).

That is, in this embodiment, the pump discharge pressure is 30 to 80 k
g f /cJ, which can be significantly lower than that of the conventional device under the same load and operating conditions as in this embodiment, which is 1.80 kg f /cJ. Additionally, the hydraulic motor braking pressure has been reduced from 320 kgf/c+N to 170 kgf/c+N in the conventional system.
This results in a significant decrease of 220 kg f/cJ.

Note that the above-mentioned effects can also be obtained by using something other than the elevating motor, such as a traveling motor or an arm turning motor, for the downstream hydraulic actuator 7. [Effects of the Invention] As is clear from the above explanation, According to the present invention, a hydraulic actuator equipped with a counterbalance valve that opposes a set pressure and a back pressure caused by a spring to an external pilot pressure via a spool and a downstream hydraulic actuator are connected in series to a common hydraulic pump. In addition, in a hydraulic lifting device or a hydraulic drive device including a hydraulic lifting device that can be driven at the same time, the upstream circuit pressure is reduced by the back pressure reducing means provided in the upstream counterbalance valve, so that the upstream circuit equipment It is possible to prevent breakdowns and shortened service life of the hydraulic actuator, reduce pump drive power, and use the potential energy of the load on the upstream side to drive the downstream hydraulic actuator, making effective use of energy.

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of an embodiment of the present invention, FIGS. 2 and 3 are sectional views of the Calanta balance valve used in the embodiment, and FIG. 4 is a hydraulic circuit diagram of a conventional device. FIG. 5 is a sectional view of a counterbalance valve used in a conventional device. 1...Hydraulic pump, 5.7...Hydraulic actuator (hydraulic motor), 6.8...Counter balance valve, 26...
Spring, 27...Spool, 28...Spring chamber, 29...Drain passage.

Claims (1)

[Claims] A hydraulic actuator equipped with a counterbalance valve that counteracts the set pressure and back pressure generated by a spring with external pilot pressure via a spool and other downstream hydraulic actuators can be connected in series to a common hydraulic pump and driven simultaneously. A counterbalance valve in a hydraulic lifting device, characterized in that, in the hydraulic lifting device or the hydraulic drive device including the hydraulic lifting device, the upstream counterbalance valve is provided with means for reducing back pressure.