JPS60256604A - Oil hydraulic circuit - Google Patents

Abstract

PURPOSE:To decrease a cost of a machine while easily and promptly warm up the machine when it is at a low temperature, by connecting each pilot line with a drain line through a check valve and a throttle. CONSTITUTION:Each pilot line 4a1-4c2 is connected with a drain line 13 through a check valve 10a1-10c2 and a throttle 12. In this way, the cost of a machine can be decreased, while the machine, when it is at a low temperature, can be easily and promptly warmed up because the maximum pilot pressure can be derived without causing the necessity for using an expensive shuttle valve of complicated construction. Further any necessity for renewing oil and/or bleeding air in the pilot lines 4a1-4c2 can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic circuit that derives the maximum pressure generated in the hydraulic circuit in an oil field circuit in which a plurality of pilot pulps operate corresponding control pulps.

[Background of the invention]

Hydraulic working machines are equipped with various hydraulic actuators, and these hydraulic actuators are driven by various control valves,
For example, it is controlled by a directional valve.

Many of these control valves are of the pilot type operated by pilot pressure generated by pilot pulp. By the way, if multiple control valves are supported f
In a configuration in which each pilot pulp is operated by
Means is used to extract the maximum pressure of the pilot pressures used to operate these control valves and use this pressure to control various devices. Such means will be explained with reference to FIG.

FIG. 4 is a circuit diagram of a conventional hydraulic circuit implementing the above means. In the figure, 1 is a hydraulic T (not shown) unit 4.
Ia is the variable displacement mechanism of the main hydraulic pump l (hereinafter represented by the swash plate).
, ib is a tilting control mechanism that controls tilting of the swash plate 1a. 2A, 2B.

2C is a direction switching valve, which controls the drive of a hydraulic actuator (not shown) connected to each valve. Each of the directional control valves 2A, 2B, and 20 has a pilot pressure receiving chamber at both ends of its spool, and is switched according to the pilot pressure E of the pilot pressure receiving chamber.
82 is a directional control valve in the pressure receiving chamber for two pilots)
(Pilot Nokurubu that generates Ilot King, 3aL
,,3aL.

are the operating levers of the pilot pulps 3a□ and 3a2, respectively. Similarly, 3b1 and 3b are directional control valves 2B
Pilot knob corresponding to (lube, 3C1゜3C2 corresponds to directional control valve 2CK)] (irontono (lube, 3bL,
, 3bL, , 3cL1, and 3cL2 are operation keys for each pilot pulp. 4a1', 4a,, 4b
i, 4bz, 4c,, 4゜21. , are pilot pipes connecting each pilot pulp and each pilot receiving chamber of each directional control valve. Reference numeral 5 designates a bailet hydraulic pump that supplies pressurized oil to each of the pilot pulps 3al to 3Cg, and 6 a relief valve that defines the maximum pressure of the pyro 71 circuit.

7@ is a shuttle valve connected between the pilot pipes 4a1 and 4C1, which selects and outputs the higher oil pressure among the oil fields occurring in the two pipes 4a, , 4a2. 7b
7c is a shuttle valve that selects and outputs the higher oil pressure among the oil pressures generated in the pilot pipes 4b1e and 4bt, and 7c is a shuttle valve that selects and outputs the higher oil pressure among the oil pressures generated in the pilot pipes 4C1 and 4c2. be. 7d is a shuttle valve that selects and outputs the higher hydraulic pressure from the outputs of shuttle valves 7a and 7b; 7e is shuttle valve 7C.

This is a shuttle valve that selects and outputs the oil field with the higher output among the 7d outputs.

4・/< 4 C27) ”'°゛o＊4'r-vA-
1, (3a L 1 and the operating lever j3cL2 of the pilot pulp 3C2 are operated, the pilot pulp 3a1 outputs hydraulic pressure according to the operating amount of the operating lever S-3aL1, and the pilot pulp 3c
, outputs hydraulic pressure according to the amount of operation of the operating biver 3cL. These oil pressures are supplied to the directional control valves 2A, 2A and 2A through pilot pipes 4a1e4C2, respectively.
It is transmitted to the pilot pressure receiving chamber of 2C, and each direction switching valve 2A
, 20 operate according to the transmitted hydraulic pressure and drive the connected hydraulic actuators.

At the same time, the oil pressure in the pilot line 4aH is changed to the shuttle valve 7.
a, 7dK and output from the shuttle valve 7d, and the hydraulic pressure in the pilot pipe 4c2 is selected from the shuttle valve 7C.
is output from. Here, temporary [, pilot pipe 4al
If the oil pressure in the pilot line 4c2 is greater than the oil pressure in the pilot line 4c2, the oil pressure in the pilot line 4a is output from the shuttle valve 7e. This oil pressure is input to the tilting control mechanism 1b, thereby increasing the tilting angle of the swash plate 1a, increasing the discharge flow rate of the main hydraulic pump l, and supporting the oilfield actuators connected to the directional control valves 2A and 20. When 3aLt and 3CLz are returned to the neutral position (all operating levers are set to the neutral position), the output of the shuttle valve 7e becomes the tank pressure, and the tilt control mechanism tb is activated to adjust the tilt angle of the swash plate 1g. becomes smaller, and the discharge amount of the main hydraulic pump l decreases.

Fifth, in the oil field circuit, when the directional control valve is switched and the oil field actuator is driven (during work), the discharge amount of the main hydraulic pump 1 is increased.

When the directional control valve is in the neutral position and the hydraulic actuator is not driven (during non-operation), the discharge amount of the main hydraulic pump l is reduced, thereby preventing wasted energy loss as much as possible. It has the functionality to do so.

However, the shuttle valve used in the above-mentioned hydraulic circuit has a complex structure due to its function.

Since precision is required, it has the disadvantage of being expensive. As the number of pilot pulps and directional control valves increases, the number of shuttle valves also increases, so the above-mentioned drawbacks become more and more noticeable.

The present invention has been made in view of the above circumstances, and its purpose is to eliminate the disadvantages of the conventional divisors and the complicated and expensive shuttle valves described above. The purpose is to provide a hydraulic circuit that can derive the maximum pressure from the pilot pressure of the pilot valve.

[Summary of the invention]

In order to achieve the above object, the present invention connects a pilot pipe connecting a pilot valve and a control valve to a common output pipe via a check valve, and The present invention is characterized in that an operating device is provided, and a drain pipe is connected to the output pipe through a throttle.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on illustrated embodiments.

:1 FIG. 1 is a circuit diagram of an oil field circuit according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted. ioa is a check valve,
Its inlet boat is connected to pilot line 4aH. Similarly, 108! .

10b□, 1Ob2. tQcl and IOc are also check valves, and each χ robot has a pilot pipe 4a2.
#4 b 1 @ 4 b 2 e 4 C1*
4 C2tlc connected. Reference numeral 11 denotes an output pipe line for outputting the highest pressure among the pilot pressures of each of the pilot valves 381 to 38c,
The exit port of C2 is output in common. Further, the tilting control mechanism 1b is connected to this output pipe line 11. 12 is a constrictor whose one end is connected to the output pipe line 11. 13 is aperture 12
This is a drain pipe connecting the other end of the tank to the tank.

FIG. 2 is a sectional view showing a specific example of the configuration of a part of the hydraulic circuit shown in FIG. 1. FIG. In the figure, the same parts as shown in Fig. 1 are given the same reference numerals, and the explanation is omitted. ◎ 15 is a block-shaped valve casing, and inside this pulp casing 5 there are 2A, 2B for each direction switching. , 2C#, -(
Hti'lil! ;! t[Ibo gb'' (・ In the same way as each directional switching valve 2A, 2B, 2C, the pipe line switched by each directional switching valve, each check valve IQal
~lOcg output line 11. The throttle 12 and the drain pipe 13 are also integrally formed within the valve casing 15. 16 is each direction switching valve 2A, 2B.

A pilot pressure receiving chamber 17 is formed by the cap 16 attached to the pulp casing 15 at both ends of 2C. Each pilot pressure receiving chamber 17 communicates with the corresponding pilot conduit 4a to 402, and also communicates with the corresponding check valve 10a1 to IOc through a conduit formed in the pulp casing 15. It is also possible to provide check valves 10a, -IOC, in each cap 16, or to integrate each inner shell 16 and form an output pipe line -f' therein.

Next, the operation of this embodiment will be explained. As described in the explanation of the conventional example shown in FIG. 4, the operation levers 3aL1, 3cL
, is operated (the amount of operation is larger for the operating lever 3aL1) will be explained. in this case,
Pilot valves 3a□ and 3C8 have values for the operation amount of the corresponding operating lever (11?). , - Pilot FF also rises - These pilot pressures are applied to pilot pipes 4al and 4, respectively.
The pressure is transmitted to the corresponding pilot pressure receiving chambers of the directional control valves 2A and 2C via Cg to operate the directional control valves 2A and 2C, and is also transmitted to the inlet boat of the check valve 10al and the inlet port of the check valve 1OC2. Ru.

However, as assumed earlier, the amount of operation of the operating lever 3aL is greater than the amount of operation of the operating lever 3cL2, so
The pilot pressure generated in the pilot valve 3al becomes larger than the pilot pressure generated in the pilot valve 3c. Therefore, the pilot pressure generated in the pilot pal 23 a 1 is transmitted to the output line 11 via the check valve toam, but on the other hand, this pilot pressure is also transmitted to the outlet port of the check valve 10 c 2. , check valve 10
The pilot pressure transmitted to the inlet boat of C2 is the check valve 1.
It is blocked by 0C2 and is not transmitted to the output pipe line 11. That is, the maximum pilot pressure is taken out to the output line 1'1.

In this case, the discharge amount of the pilot hydraulic pump 5 and the opening area of the throttle 12 are set appropriately.

('Then, the maximum pilot pressure is introduced to the tilting control mechanism ib, and the tilting angle of the swash plate 1a increases accordingly,
The discharge amount of the main hydraulic pump l increases, and the hydraulic actuator is driven without any trouble. Operation lever 3aL1, 3cL2
When both are returned to the neutral position, the pressure oil in the output line 11 is discharged to the tank via the throttle 12 and the drain line 13, and the pressure in the output line 11 becomes the tank pressure, thereby controlling the tilting. The mechanism 1b operates, the tilting angle of the swash plate 1m becomes smaller, and the discharge amount of the main hydraulic pump 1 decreases.

In this way, in this embodiment, check valves and throttles with a simple structure and low cost are used instead of shuttle valves, and each pilot pipe is connected to the inlet boat of each check valve, and the outlet boat of each check valve is connected to the inlet boat of each check valve. Since the output pipe is commonly connected to the two, it is possible to guide the maximum pressure of the piston pressure generated in the pilot valve to the tilting control mechanism 1b with a simple and inexpensive configuration.

Furthermore, if a part of the hydraulic circuit is configured as shown in FIG. 2, the valve casing can be fabricated much more easily than when a shuttle valve is used. Furthermore, since the throttle is disposed between the output pipe and the drain pipe, the control characteristics of the main hydraulic pump can be adjusted by appropriately selecting the diameter of the opening of the throttle. Furthermore, in the conventional circuit shown in FIG. 4, it is difficult to move the pressure oil smoothly due to the presence of multiple shuttle valves, whereas in this embodiment, the pressure oil in the pilot circuit is Pressure oil is discharged into the tank via a check valve and a throttle, allowing for smooth movement of pressure oil.This allows warm-up to be performed in a short time when warming up at low temperatures, and hydraulic machinery The operational responsiveness of the circuit does not deteriorate (and there is no need to renew the oil or bleed air from the pilot pipe, which were required in the conventional circuit).

FIG. 3 is a circuit diagram of an oil field circuit according to another embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 20 is a pressure detector; 21 is a controller that inputs the signal of the pressure detector 20 and performs the required processing; 22 is a proportional solenoid valve that is driven according to the output signal of the controller 21; . This embodiment differs from the rabbit embodiment in that the output pipe 1.
The only difference is that instead of directly controlling the tilting control mechanism 1b with the pressure of 1, the tilting control mechanism 1b is controlled via a pressure detector 20, a controller, a roller 21, and a proportional solenoid valve 22. It's the same.

The maximum pilot pressure taken out by the output line 11 is detected by the pressure detector 20 and converted into an electric signal corresponding thereto. The controller 21 inputs this signal, performs necessary processing, and outputs the resulting signal to the proportional solenoid valve 22. The proportional solenoid valve 22 is driven by an amount corresponding to this signal, and pressure oil corresponding to this driven amount is supplied from the pilot oilfield pump 5 to the tilt control mechanism 1b, thereby controlling the discharge amount of the main hydraulic pump 1. .

In this way, in this embodiment, a check valve and a throttle are used in place of the shuttle valve, so that the same effect as in the rabbit embodiment can be achieved. Also, instead of directly controlling the tilting control mechanism using the pilot pressure in the output pipe, the pilot pressure in the output pipe is detected and the controller and proportional solenoid valve are driven and controlled based on that signal. Therefore, the discharge amount of the main hydraulic pump can be appropriately controlled with high precision.

In addition, in the description of the above embodiment, an example was explained in which the pilot pressure of the output pipe is used to control the flow rate of the main hydraulic pump. It can also be used as a control signal for engine speed.

〔Effect of the invention〕

As described above, in the present invention, each pilot pipe is connected to a corresponding check valve, each of these check valves is commonly connected to an output pipe, and this output pipe is connected to a drain pipe through a restriction. Since it is connected to the pipe, the maximum pilot pressure can be derived without using an expensive shuttle valve with a complicated structure, and warm-up at low or high temperatures can be performed easily and quickly. Furthermore, there is no need to replace the oil in the pilot pipe or bleed air.

[Brief explanation of drawings]

Figure xi is a circuit diagram of a hydraulic circuit according to an embodiment of the present invention.
3 is a circuit diagram of an oil field circuit according to another embodiment of the present invention, and FIG. 4 is a circuit diagram of a conventional hydraulic circuit. It is. l...Main hydraulic pump, Ha...Swash plate,
ib...Tilt control mechanism, 2A, 2B, zC...
...Directional switching valve, 3a1-3C2...Pilot pulp, 3a'L1-3cL2...Operation lever, 4a1-4C2...Pilot pipe line,
5...Pilot pump, ,10a1~1O
C2... Check valve, 11... Output pipe line,
12... Throttle, 13... Drain pipe. Agent: Patent attorney Junjibu Take (and one other person). Figure 1

Claims (1)

[Scope of Claims] 1. A hydraulic circuit comprising a plurality of pilot pulps that generate pilot pressure according to a manipulated variable, and a plurality of control pulps each connected to each of these pilot pulps by a pilot pipe, An output pipe that commonly connects each pilot pipe through a check valve, a device that operates according to the pressure of this output pipe, and a drain pipe that is connected to the output pipe through a throttle. An oil field circuit characterized by being provided with. 2. The hydraulic circuit according to claim 1, wherein the device is a discharge amount control means for a hydraulic pump. 3. The hydraulic circuit according to claim 1, wherein the device is a pressure detection means.