JPS62118107A - Warming-up of hydraulic pilot circuit - Google Patents

Abstract

PURPOSE:To start operation safely and reliably even during cold winter by arranging a relief valve and a changeover valve in a branch path from a pilot piping. CONSTITUTION:A relief valve 22 and a two position type changeover valve 13 are arranged in an oil path 6 branched from a pilot piping while a back pressure valve 14 is coupled. Since the oil heated by the relief valve 22 and the back pressure valve 14 during engine warm-up operation will circulate through a hydraulic pilot circuit and warm the peripheral machineries simultaneously, the operation can be started safely and reliably even during cold winter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a warming amplifier for a hydraulic pilot circuit for remote control.

2. Description of the Related Art Conventionally, in a hydraulic circuit in a hydraulic remote control system, even if the operating lever is operated while the engine is rotating, the flow of oil in the pilot circuit is very small, making it difficult to warm up the circuit.

That is, in the conventional hydraulic remote control circuit diagram shown in FIG.
When not operated, the entire amount flows out from the relief valve 22,
It enters the tank 20 via an oil path. When one of the pilot valves, for example 7, is pushed in by an operating lever (not shown), the pressure oil from the pilot pump 3 passes through the oil path 5, is pressure regulated by the pilot valve 7, and then flows into the oil path 10. It enters the pilot oil chamber 16 on the left end side in the figure of the hydraulic switching valve I2, moves the spool of the hydraulic switching valve 12 to the right, switches the oil path, and operates the actuator 15 such as a hydraulic cylinder. On the other hand, the oil filling the pilot oil chamber 17 on the right end side of the hydraulic switching valve 12 passes through the oil path 11 to the pyro on the side that is not operated.

The oil passes through the neutrally open oil path in the valve 8 and is returned to the tank 20 from the oil path 9.

At this time, the amount of pressure oil sent through the oil passage 10 is only the volume of the stroke in which the spool of the hydraulic switching valve 12 moves to the right, and is small, and no matter how many times the pilot valve 7 is operated. The oil sealed in the pilot oil chamber 16 and the oil passage 10 is only pressurized and depressurized and reciprocated.

This means that even if the pilot valve 8 is pushed into operation using the operating lever, the spool of the hydraulic switching valve 12 will only move in the opposite direction, and the oil in the pilot oil chamber 17 and oil passage 11 will be in the same state as above. It is something that moves.

Therefore, start the engine, warm it up for a long time, and then operate the control lever to control the pilot valve 7.
．． 8, the oil temperature in the tank 20 gradually rises, but the pilot oil chamber 16.17, oil passage 5.9.10
, 1 does not rise easily, so especially when starting work in cold weather, piping resistance in the pilot pressure circuit increases due to the influence of outside temperature, so operate the operating lever to operate the pilot valve 7.8. Even if this is the case, the movement of the spool of the hydraulic switching valve 12 will be slow.

Problems to be Solved by the Invention During the cold winter months when the outside temperature is low, in machines that employ the hydraulic remote control method, even after the start of operation, the pressure signal from the pilot valve and
A time lag is likely to occur between the switching operation of the hydraulic switching valve, and the driver feels uncomfortable during operation, and the response is unstable, which is extremely dangerous.

In view of these problems, the present invention has been devised to introduce the oil in the tank, whose temperature gradually rises when the engine is started during its warming up, into the pilot oil chamber of the hydraulic switching valve via the pilot valve and pilot piping. After that, by circulating the oil back to the tank, the hydraulic remote control system is warmed up at the same time, thereby providing a hydraulic pilot circuit that can perform safe and reliable operation from the start of work.

Means for Solving the Problem: During the operation of the prime mover that drives the main pump, a back pressure valve is provided in the outflow oil path from the relief valve for adjusting the discharge pressure of the pump for the pilot oil pressure source, which is driven at the same time, to the tank. The upstream oil passage is led to the pressure oil inflow port of the two-position switching valve, which has a plurality of outlet ports each communicating with the pilot oil chamber of the actuator operating hydraulic switching valve through independent oil passages. When the two-position switching valve is closed, the pressure oil inflow port and the outlet port are independently cut off, and when it is open, the pressure oil inflow port and the outlet port are in communication with each other.

Operate the operation switching valve to the open side to branch the upstream oil passage of the back pressure valve to the pilot oil chamber of the hydraulic switching valve for actuator operation, and when warming up with the pilot valve in the neutral position, the oil in the tank will The temperature gradually rises. On the other hand, the pilot pump sucks in the oil whose temperature has risen in the tank and tries to send it to the pressure oil inlet port of the pilot valve, but since the boat is closed, the entire amount of pressure oil passes through the relief valve. It is further heated and regulated to a specified pressure by the action of the back pressure valve, and flows into the two-position switching valve, where it is branched, passes through the pilot oil chamber of the hydraulic switching valve for actuator operation, and flows into the pilot piping and pilot valve. When in neutral, the tank boat circulates to the tank via the open passage. When the oil temperature in the tank rises due to warm-up, this VAN oil warms the 24-ring circuit and peripheral equipment, allowing normal, smooth and safe operation at the end of warm-up.

Next, at the start of operation, when the previously operated switching valve is switched to the closed state, the oil discharged from the pyro pump is supplied with a predetermined pressure to the pressure oil inlet port of the pilot valve, and the excess oil is The oil is returned to the tank through a relief valve and a back pressure valve. Furthermore, the pilot oil chambers of the hydraulic switching valves for operating the actuator are held separately in separate closed chambers for the left and right sides, so that a circuit exactly the same as that of the original hydraulic remote control system is formed.

Embodiments An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which 2 is a main pump;
A pilot pump 3 is driven by the engine 1 and is connected to a tank 20 via a suction strainer 21 through an oil line.

The discharge port of the main pump 2 communicates through an oil passage 18 with a hydraulic switching valve 12 that operates an actuator 15 such as a hydraulic cylinder, and the return oil is passed through an oil passage 19 and a return filter 23 to a tank 20.

The discharge port of the pilot pump 3 communicates with the pressure oil inflow ports P, P of the pilot valve 7.8 through an oil passage 5 equipped with a filter 4 and a relief valve 22 for maintaining the pilot oil pressure source pressure at a specified value. , tank boats R and R join together and communicate with the tank 20 via an oil passage 9. On the other hand, oil path 5
The downstream oil passage 6 of the relief valve 22 which is branched from the
Connected to the pressure oil inflow port of the two-position switching valve 13,
An intermediate point of the core oil passage 6 branches off, has a back pressure valve 14, and is provided with an oil passage 28 leading to a tank 20.

The switching valve 13 is a pilot oil chamber 16 of the hydraulic switching valve 12.
．． It has an outlet boat connected to oil passages 26 and 27 that communicate separately with 17, and while each remains an independent circuit, at the same time,
This is a switching valve that has the function of closing or opening the pressure oil in the oil passage 6, and is opened and closed by an electric signal sent via distribution M25 by a switch 24 placed in a convenient position for operation, such as near the driver's seat. It is something. This opening/closing operation is
In this embodiment, the switching valve 13 is illustrated as a solenoid valve, but
The method is not limited to this, and any method such as a cable, loft, direct manual control method, or pilot pressure control method may be used as long as it can be operated reliably and easily from a predetermined position.

In addition, in the embodiment shown in Fig. 1, the hydraulic switching valve 12 is a center spring type three-position one valve, and therefore there are two pilot oil chambers on the left and right, but the pilot oil chamber is in two positions with only one chamber. Of course, this proposal can also be applied when there are three or more pilot oil chambers in a valve or multiple cedar hydraulic switching valve, and in that case, the outlet port of the switching valve 13, the boat, and each pilot oil It is only necessary to increase or decrease the number of oil passages that communicate the chambers.

Next, the operation of the hydraulic circuit having the above configuration will be explained with reference to FIG. Switch 24 of the operating device located near the driver's seat
is closed and the switching valve 13 is switched from the A position to the B position.
The pressure oil discharged by the pilot pump 3 is regulated to a predetermined pressure by the relief valve 22, passes through the oil path 5, reaches the pressure oil-inflow port PSP of the pilot valve 7.8, and the pressure oil that has passed through the relief valve 22 is maintained at a constant pressure by the action of the back pressure valve 14 and flows into the switching valve 13 through the oil passage 6. Since the switching valve 13 is in the B position due to the above operation, it is branched in the internal passage, flows into the pilot oil chamber 16 through the oil passage 26, flows into the pilot oil chamber 17 through the oil passage 27, and then flows into the pilot oil chamber 17 through the oil passage 26. , passes through the oil passage 10.11, which becomes the pilot hydraulic piping during normal operation, and connects the pilot valve 7.
．． Guided by 8 pilot pressure boats Q and Q.

The pilot valve 7.8 is a known pressure regulating valve and has a structure as shown in FIG. 2, and when the operating lever is in the neutral position, the tank boat R communicates with the pilot pressure boat Q through an internal passage. Therefore, the oil flowing from the oil passage 10.11 passes through the neutral open passage of the pilot valve 7.8 to the tank boat R,
After reaching H, it returns to the tank 20 via the oil path 9. When the engine 1 is started to warm up, the main pump 2 and pilot pump 3 connected to it are driven together, and the main pump 2 sucks oil from the tank 20 via the suction strainer 21 and discharges the oil. Since the oil circulates back to the tank 20 through the oil passage 18, the neutral bypass circuit of the hydraulic pressure switching valve I2, the oil passage 19, and the return filter 23, the oil temperature in the tank 20 gradually rises. At the same time, the pilot pump 3 also sucks heated oil in the same tank 20, and the discharged oil is guided through the oil line 5 to the pressure inlet boat of the pilot valve 7.8, which is connected to the Byront valve 7.8. Since it is closed when the is neutral, the entire amount is relieved from the relief valve 22, and at the same time it is heated, and furthermore, due to the action of the back pressure valve 14, it passes through the oil passage 6 while maintaining a constant pressure, and enters the B position passage of the switching valve 13. Oil line 26.27
The flow is divided into the pilot oil chambers 16 and 17, respectively, and then the oil passages 10 and 11, the pilot pressure boat Q of the pilot valve 7.8, the neutral open passage, and the circulation circuit from the tank boat R1 oil passage 9 to the tank 20. As it passes through the air, the hydraulic pilot circuit and peripheral equipment gradually warm up. Next, when warming up the hydraulic pilot valve is complete and you want to start operating the machine, switch 2.
4 is opened and the switching valve 13 is returned to the A position, the pressure oil discharged from the pilot pump 3 passes through the oil passage 5 and is regulated and guided to the pressure oil inlet ports P, P of the pilot valve 7.8. However, since the oil passage 6 on the upstream side of the back pressure valve 14 is closed by the pressure oil inflow port at the A position of the switching valve 13, the entire amount of pressure oil relieved from the relief valve 22 is transferred to the back pressure valve I4. It flows into the tank 20 through the.

Furthermore, by returning the switching valve 13 to the A position, the oil passages 26.27 that independently communicate with the left and right pilot oil chambers 16.17 of the hydraulic switching valve 12 are also closed and are mutually cut off. Therefore, the pilot oil chambers 16 and 17 are also independent from each other. In this state, the pilot valve 7.8 is operated and the signal pressure oil is passed from the pilot pressure bow) through the oil passage 10 or 11 to the pilot oil chamber IG or 1.
7, the spool of the hydraulic switching valve 12 moves to the right or left, switches the pressure oil from the main pump 2, and operates the actuator 15.

Effects of the Invention By adding the hydraulic pilot circuit warming-up circuit configuration according to the present invention, the oil heated during engine warm-up is further heated while passing through the relief valve, and the oil pressure increases. Since it circulates within the pilot circuit and warms up its peripheral equipment at the same time, pressure oil flow resistance and equipment operating resistance in the circuit are reduced. Therefore, even when operating in cold winter weather, the engine can be operated manually in a single hour after starting the engine, and there is no time lag phenomenon seen in conventional hydraulic remote control systems, allowing safe and reliable operation. You can start.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a sectional view showing the internal structure of a pilot valve, and FIG. 3 is a hydraulic circuit diagram of a conventional hydraulic remote control system. 3...Pilot pump 7...Pilot valve 8...Pilot valve 12...Hydraulic switching valve 13...Switching valve 14... ...Back pressure valve I6...Pilot oil chamber 17...Pilot oil chamber 24...Switch P...Pressure oil inflow port Q...・Pilot pressure boat R・・・・・・Tank boat or higher

Claims (1)

[Claims] In a hydraulic pilot circuit that operates an actuator by switching a hydraulic switching valve in response to a pressure signal from a pilot valve, a back pressure valve is installed in the middle of an oil path that branches from the discharge side circuit of the pilot hydraulic pressure source and leads to the tank via a relief valve. is provided, and when the upstream oil passage of the back pressure valve is closed, the outlet port that communicates through the oil passage between the pressure oil inflow port and the pilot oil chamber of the hydraulic switching valve for actuator operation is independently shut off. The warm-up circuit configuration of the hydraulic pilot circuit is characterized in that when opened, the pressure oil inflow port and outlet port are guided to the pressure oil inflow port of a switching valve that communicates with each other.