JPH0529200Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention relates to a hydraulic circuit for a steering gear.
The present invention relates to a hydraulic circuit provided with a circuit blocking valve for supplying and discharging hydraulic oil to a steering cylinder. This is used in the field of hydraulic steering gears.

[Conventional technology]

Some hydraulic circuits for steering gears include a circuit blocking valve having three functional positions in an oil passage that supplies and discharges hydraulic oil from a hydraulic pump to a steering cylinder. The circuit blocking valve is configured so that its functional position can be switched by the self-pressure of the hydraulic oil acting on the oil passage.

By the way, when the hydraulic pump is driven by an electric motor and is supplying and discharging hydraulic oil to the steering cylinder via the circuit blocking valve, if the power is lost for some reason, the rotation of the hydraulic pump will stop and the steering operation will be interrupted. become unable to do so. Since the force of the water current acts on the rudder plate, unless the movement of the ram is restrained to maintain the amount of steering, it may become impossible to change the desired course of the ship, resulting in an extremely dangerous situation. .

Therefore, regarding the hydraulic circuit for the steering gear,
When the supply of hydraulic oil from the hydraulic pump is stopped, the functional position of the circuit blocking valve is switched due to the loss of self-pressure so that the hydraulic oil in the steering cylinder does not move.

When the main power is lost during steering, the rudder angle may have to be further changed, and the classification standard requires that the auxiliary power source be used to continue steering until the main power is restored. That is required. However, the amount of electric power obtained from this power source is generally extremely small compared to the main power source.

On the other hand, when the electric motor is restarted to drive the hydraulic pump while the movement of the hydraulic oil in the steering cylinder is blocked by the circuit blocking valve, the hydraulic oil discharged by the rotation of the hydraulic pump flows. will be blocked by the circuit blocking valve. As a result, a large load is placed on the electric motor, making it difficult to restart it using the auxiliary power source described above.

Therefore, it is necessary to be able to start the electric motor at a low load in an emergency when an auxiliary power source must be used, and for this purpose, the hydraulic circuit shown in Fig. 4, which uses a new circuit blocking valve, has been considered. There is.

In addition to the hydraulic pump 2 that supplies hydraulic oil to the steering cylinder 4, another pump is provided.
The auxiliary pump 31 is simultaneously driven by the electric motor 7 that drives the hydraulic pump 2, and its discharge pressure can be generated as pilot pressure. Therefore, when the pressure is applied to the pressure sensing portion 8a of the circuit blocking valve 8 via the electromagnetic valve 10, the functional position of the circuit blocking valve 8 is switched.

According to this, when the circuit blocking valve 8 is in the functional position Q, the hydraulic oil from the hydraulic pump 2 can be returned to the hydraulic pump 2 via the communication path 32, so the state is almost unloaded. Hydraulic pump 2
can be driven. As a result, when the main power supply is lost, the electric motor 7 that drives the two pumps 2 and 31 can be restarted in a low load state using the auxiliary power supply with low power, and the auxiliary pump 31 can be used to restart the circuit blocking valve 8.
It is possible to generate pilot pressure for switching the functional position of the

That is, when pressure is generated to overcome the elastic force of the spring 12 of the circuit blocking valve 8 and switch the functional position, the hydraulic oil from the hydraulic pump 2 is supplied to and discharged from the steering cylinder 4, so that the desired steering can be continued. become.

[The problem that the idea aims to solve]

However, in order to generate the pilot pressure to switch the functional position of the circuit blocking valve mentioned above,
The above-mentioned auxiliary pump is required, which increases costs. Furthermore, when the auxiliary pump fails, the circuit blocking valve cannot be switched, resulting in a situation where the vehicle becomes unable to steer.

This invention was made in view of the above problems,
The purpose of this is to be able to restart the electric motor that drives the hydraulic pump using a small auxiliary power source when the main power source is lost, and to operate the circuit using only the hydraulic pump for steering without the need for the auxiliary pump mentioned above. It is an object of the present invention to provide a hydraulic circuit for a steering gear, which enables switching of the functional position of a blocking valve, and also enables reduction of trouble occurrence factors and cost reduction.

[Means to solve the problem]

The features of the present invention will be described with reference to FIG. 1. A circuit blocking valve 8 is provided in an oil passage 14 for supplying and discharging hydraulic oil from a hydraulic pump 2 interposed in a closed circuit to a steering cylinder 4. By applying pilot pressure to the circuit blocking valve 8 provided in the
The hydraulic circuit for the steering gear is configured to switch the functional position, and the circuit blocking valve 8 communicates between the variable displacement hydraulic pump 2 and the steering cylinder 4, and can be operated in either forward or reverse directions. A functional position P that allows hydraulic oil to flow through the hydraulic pump 2 and a check valve 9 installed in the spool blocks the hydraulic pump 2 and the steering cylinder 4, and also connects the suction path and the discharge path of the hydraulic pump 2. It is a two-position switching valve with a functional position Q, one of which is switched by pilot pressure, is held by a spring 12 and an oil line 14 connecting the hydraulic pump 2 and the circuit blocking valve 8.
A valve 19 is arranged to generate pressure in the hydraulic fluid of the hydraulic pump 2 regardless of the functional state of the circuit blocking valve 8, and the pilot pressure is used to switch the functional position of the circuit blocking valve 8. It is becoming more and more common.

〔Example〕

The present invention will be described in detail below based on examples thereof.

FIG. 1 is an overall system diagram of a hydraulic circuit 1 for a steering gear according to the present invention, in which hydraulic oil from a hydraulic pump 2 can operate a ram 4a that rotates a rudder shaft 3.

The steering cylinder 4 consists of two cylinders 4A and 4B provided in a closed circuit, and a rudder shaft rotation arm 5 is installed in the center of a ram 4a that moves to supply and discharge hydraulic oil in both cylinders by reciprocating movement of the ram 4a. An engagement pin 6 for rotating the is provided.

The hydraulic pump 2 that supplies and discharges hydraulic oil to the steering cylinder 4 is a variable displacement pump driven by an electric motor 7 that is driven by a main power source or an auxiliary power source (not shown), and the hydraulic oil is discharged correctly. It is reversible and can take a desired direction and discharge flow rate depending on the steering direction and steering speed.

A circuit blocking valve 8 is provided between the hydraulic pump 2 and the above-mentioned steering cylinder 4, and the circuit blocking valve 8 switches its functional position when the pressure of the hydraulic oil from the hydraulic pump 2 acts.

One of the functional positions of the circuit blocking valve 8 is a functional position P that communicates between the hydraulic pump 2 and the steering cylinder 4 and allows hydraulic oil to flow in forward and reverse directions, and the other position is is a functional position Q in which two check valves 9 installed in the spool block off the hydraulic pump 2 and the steering cylinder 4, and communicate the suction path and the discharge path of the hydraulic pump 2. These functional positions are switched by pilot pressure, which will be described below, and for this purpose one functional position is held by a spring 12, which will be described later.

A structural example of this circuit blocking valve 8 will be described later, but in order to switch its functional position, the hydraulic circuit 1 includes:
A solenoid valve 10 is provided which switches upon loss of mains power. Hydraulic pump 2 introduced via check valve 11 if mains power is not lost
The hydraulic fluid acts as a pilot pressure on the pressure sensing portion 8a of the circuit blocking valve 8 via the functional position R of the solenoid valve 10, and the built-in spring 12 is contracted by this pressure to take the functional position P.

On the other hand, when the main power is lost, the solenoid 10a of the solenoid valve 10 is demagnetized and switched to the functional position S, the hydraulic oil in the pressure sensitive part 8a is returned to the oil tank 13, and the functional position Q is changed by the spring 12. He is starting to make a comeback.

The circuit blocking valve 8 is, for example, as shown in FIG. 2, and has two inlet/outlet ports 15a connected to a conduit 14 constituting a discharge path and a suction path for supplying and discharging hydraulic oil from the hydraulic pump 2. , 15b and supply/discharge ports 16a, 16b connected to the respective cylinders 4A, 4B of the steering cylinder 4 are connected to the casing 17.
A spool 18 having an opening therein and having check valves 9, 9 therein is displaceably mounted.

A solenoid valve 10 is provided at one end of the spool 18.
A pressure sensitive part 8a is formed into which hydraulic pressure is introduced, and a spring 12 compressed by the pressure is arranged at the other end. Note that the spool 18 is provided with lands at appropriate locations for switching the supply and discharge of hydraulic oil, and corresponding oil grooves 23 and the like are formed on the inner surface of the casing 17.

The oil passage 14 connecting the circuit blocking valve 8 and the hydraulic pump 2 is provided with a valve 19 (a first (see figure), and the upstream side of the valve 19 is connected to the check valve 1 so that the pilot pressure is used to switch the functional position of the circuit check valve 8.
1 to the electromagnetic valve 10 described above.

The check valve, whose valve 19 generates the pressure necessary to switch the circuit blocking valve 8 into the functional position P, is also a pressure regulating valve, the pilot pressure of which is applied to the spring 12.
The elastic force is selected to the extent that it exceeds the elastic force of Note that the oil passage 14 is provided with a check valve 20 that is parallel to the valve 19 and allows flow in the opposite direction, and the hydraulic oil at that time is supplied to the valve 19 and the circuit blocker, as shown by solid lines or broken lines, for example. It circulates through valve 8 and check valve 20.

In the steering gear hydraulic circuit 1 having the circuit blocking valve 8 having such a configuration, the electric motor 7 can be restarted under a low load in the following manner when the main power source is lost.

First, we will explain the steering operation when the main power source is functioning normally.

While the hydraulic pump 2 is driven by the electric motor 7, the solenoid 10a of the electromagnetic valve 10 is separately energized by receiving electric power and set to the functional position R. As a result, the pressure sensing portion 8a of the circuit blocking valve 8 has the check valve 11
A pilot pressure is then applied via the solenoid valve 10 to switch it into the functional position P against the force of the spring 12. The circuit blocking valve 8 is in the state shown in FIG. 3, and the hydraulic pump 2 and the steering cylinder 4 are communicated with each other.

When hydraulic oil is supplied through the oil passage 14 in the direction of the arrow 21, for example, the hydraulic oil enters the annular oil groove 23 as shown by the arrow 22 from the outlet/outlet 15a, and flows through the supply/discharge port 16.
a to cylinder 4A. The ram 4a is pushed out by the cylinder 4A, and the rudder shaft 3 is rotated via the engagement pin 6 and the rudder shaft rotation arm 5. Due to the movement of the ram 4a, the hydraulic oil in the cylinder 4B is returned to the hydraulic pump 2 from the supply/discharge port 16b, through the oil groove 24, and from the outlet port 15b as shown by an arrow 25.

If the main power source is lost while the steering operation is being performed in this manner, the rotation of the electric motor 7 will stop, and the discharge from the hydraulic pump 2 will cease. At the same time, the solenoid 10a of the electromagnetic valve 10 (see FIG. 1) is also demagnetized, so that it is restored to the functional position S by the spring 10b. As a result, the pressure sensing portion 8a is communicated with the oil tank 13 via the solenoid valve 10, and the spring 12 brings the circuit blocking valve 8 into the functional position Q.

Therefore, even if the rudder shaft 3 attempts to rotate due to the action of water flow on the rudder plate, the steering cylinder 4
The hydraulic oil inside is blocked by the circuit blocking valve 8, which is in the state shown in FIG. That is,
Communication between the oil groove 23 and the outlet/outlet 15a and between the oil groove 24 and the outlet/outlet 15b are blocked by each land,
A space 26 within the spool 18 that communicates with each other.
This is because the oil hole 27 is also blocked by the check valve 9 that closes it.

The check valve 9 is built into the spool 18 because, although not shown, a relief valve is provided between the circuit blocking valve 8 and the steering cylinder 4 to ensure the safety of the hydraulic circuit. Because there is. That is, even if there is an abnormal increase in the working oil pressure on the steering cylinder side, it is regulated so that it does not affect the hydraulic pump side. In addition, even if the hydraulic pressure increases excessively on the hydraulic pump side, it can be regulated by the relief valve.

In the functional position Q of the circuit blocking valve 8 as described above, the outlet/outlet ports 15a and 15b are in direct communication. Therefore, even if the electric motor 7 is driven by the auxiliary power source, the hydraulic oil moving in the oil passage 14 by the hydraulic pump 2 can pass through the circuit blocking valve 8 as shown by the arrow 28. As a result, the motor 7 will be restarted at an extremely low load.
The hydraulic pump 2 can be driven even by an auxiliary power supply with a small supply power. When the rotation of the hydraulic pump 2 increases to a desired level, the solenoid 10a of the electromagnetic valve 10 is energized, and the hydraulic pressure is applied to the circuit blocking valve 8.
The steering angle can be changed by acting on the pressure sensing portion 8a.

In that case, the valve 19 generates pilot pressure in the hydraulic fluid from the hydraulic pump 2, so the pressure is applied to the pressure sensitive part 8a via the check valve 11 and the solenoid valve 10.
It acts on That is, without the valve 19, the pressure of the hydraulic oil from the hydraulic pump 2 cannot rise, but since the pressure of the hydraulic oil is regulated to the set value by the valve 19, the hydraulic oil is supplied to the steering cylinder 4. Pilot pressure can be generated using only the hydraulic pump 2.

[Effect of idea]

As can be seen from the detailed description of the embodiments above, the present invention is a circuit that has a functional position that allows hydraulic oil to flow in forward and reverse directions, and a functional position that allows the hydraulic oil to flow in the forward and reverse directions, and which is shut off by a check valve and communicates with the primary side. A blocking valve is provided in the closed circuit that supplies and discharges hydraulic oil from the hydraulic pump to the steering cylinder, and a valve that generates pilot pressure is provided in the oil path connecting the hydraulic pump and the circuit blocking valve. The pressure allows the functional position of the circuit blocking valve to be smoothly switched. Moreover, in a state where the main power source is lost, the electric motor that drives the hydraulic pump can be restarted even with a small auxiliary power source, thereby reducing the causes of trouble and reducing costs.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram of a closed hydraulic circuit for a steering gear to which the present invention is applied, and Fig. 2 is an example of a circuit blocking valve, with the connection between the hydraulic pump and the steering cylinder cut off. FIG. 3 is an operating state diagram of a circuit blocking valve in which a hydraulic pump and a steering cylinder communicate with each other, and FIG. 4 is a conventional hydraulic circuit diagram. DESCRIPTION OF SYMBOLS 1... Hydraulic circuit, 2... Hydraulic pump, 4... Steering cylinder, 8... Circuit blocking valve, 9... Check valve, 12... Spring, 14... Oil path, 18...
...Spool, 19...Valve, P, Q...Functional position.

Claims (1)

[Claims for Utility Model Registration] A circuit blocking valve is provided in an oil passage that supplies and discharges hydraulic oil from a hydraulic pump to a steering cylinder, which is interposed in a closed circuit, and pilot pressure is applied to the circuit blocking valve. Accordingly, in a hydraulic circuit for a steering gear whose functional position is switched, the circuit blocking valve communicates between a variable displacement hydraulic pump and a steering cylinder, and operates in forward and reverse directions. A functional position for circulating hydraulic oil, and a functional position for blocking the hydraulic pump and the steering cylinder by a check valve built into the spool, and communicating the suction path and the discharge path of the hydraulic pump. A two-position switching valve, one of whose functional positions is switched by pilot pressure, is held by a spring and is connected to the oil line connecting the hydraulic pump and the circuit blocking valve.
A valve is provided that generates pressure in the hydraulic fluid of the hydraulic pump regardless of the functional state of the circuit blocking valve, and the pilot pressure is used to switch the functional position of the circuit blocking valve. Characteristic hydraulic circuit for steering gear.