JPS6372903A - Drive circuit for hydraulic motor - Google Patents

Abstract

PURPOSE:To increase a rotational speed and ensure starting by allowing a motor capacity to be automatically set small, within such a range as a load torque can constantly be borne. CONSTITUTION:An automatic switching valve 8 is connected to the hydraulic actuator 7 of a hydraulic motor 3, and a spring 12, which pushes a valve spool away to such a position as to allow the capacity of the hydraulic motor 3 to be small, is provided to the automatic switching valve 8, with one end of the spool connected via a sequence valve 15 to a pump and the other end directly connected to the pump so as to allow the pressure receiving area at the end of the spool to have the correlation of F1/S1<P0<F1/(S1-S2), where, the pressure receiving area at one end-S2, the pressure area at the other end-S1 the setting pressure of the sequence valve 15-P0, and the bounce of the spring 12-F1. The aforesaid constitution allows the capacity of the hydraulic motor 3 to be automatically set small within such a range as a load torque can constantly be borne, and results in a high rotational speed and a stable starting.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) This invention is a hydraulic motor suitable for the drive part of a mooring switch, etc.
(Prior Art) The rotation speed of a mooring winch may be small when pulling a ship to a quay, but it is required to be sufficiently high when winding out a mooring line or winding it up with a light load. This is to speed up the mooring work, and to quickly wind up the mooring line that has been untied from the quay when leaving the berth to prevent it from becoming entangled in the propeller.

Such switching characteristics can be obtained by driving the motor at a constant horsepower, but conventional constant horsepower drive circuits use a variable capacity hydraulic system for the motor, and its capacity (per revolution of the motor) is The required amount of oil was directly controlled. That is, in this case, when the capacity is decreased, the torque decreases but the rotation increases, and when the capacity is increased, the rotation decreases but the torque increases.

(Problem to be Solved by the Invention) However, in such a conventional constant horsepower drive circuit, even if the motor capacity is maximized, the rotation does not become zero, so there is a limit to the rotation speed that can be lowered. In order to control the speed in a range smaller than that, additional means such as a flow rate control valve or a variable displacement pump are required, and the overall operation becomes complicated.

The object of the present invention is to obtain a constant horsepower drive circuit for a hydraulic motor that has a simple structure and is easy to operate.

(Means for Solving the Problems) A hydraulic motor drive circuit according to the present invention includes a variable displacement hydraulic motor equipped with a hydraulic actuator for changing the motor volume 1, and a hydraulic fluid supplied to the motor. a flow control valve that controls the flow rate;
It consists of an automatic switching valve that controls the displacement of the motor by switching the direction of the flow of hydraulic oil acting on the actuator. The switching valve has a spring that pushes the valve spool to a position where the capacity of the motor is reduced, and one end of the spool, the side without the spring, is applied with oil pressure P on the inlet side of the motor, and the spool The pressure P is applied to the other end via a sequence valve. The end pressure receiving area of the spool is 81 on the side without the spring and S on the side with the spring, and the set pressure of the sequence valve is P. , if the repulsive force of the spring is FI, then FI/S1<Po<Fl,
There is a relationship of /(s, st).

(Function) When the flow control valve is opened while the motor is stopped, hydraulic pressure is applied to the inlet side of the motor, and the value P becomes F1/
It becomes larger than S1. Then, the spring contracts and the spool moves, the switching valve switches to the capacity increase position, and the actuator increases the capacity of the motor. Generally, a variable displacement motor cannot be started if its capacity is reduced to less than about 30% of its maximum value. However, in this invention, in this way,
As soon as the flow 1 control valve is opened, the motor capacity increases, so the motor starts reliably.

Next, when the flow rate control valve is further opened and the rotation of the motor is increased, the load increases and the pressure P on the inlet side of the motor increases. Pressure P is the set pressure of the sequence valve (■). When the temperature rises higher, the sequence valve opens and pressure P is also applied to the other side of the spool.
acts, the switching valve is switched to the capacity M position, and the actuator reduces the capacity of the motor by 1.

In this way, as the motor capacity gradually decreases, the torque that can be generated decreases, so the load becomes relatively large and the pressure P increases. When the pressure P becomes greater than F,/(Sl-St), the spring contracts again, the spool moves, and the switching valve moves to the capacity increasing position. As the motor capacity gradually increases, the torque that can be generated increases, so the load becomes relatively smaller and the pressure P decreases. When the pressure P becomes smaller than PI/(S, -S,), the switching valve is in the true position. In this way, the motor capacity is automatically controlled so that the pressure P is always equal to P,/(S, -5t), and therefore Fl/ If you adjust the value of (Sl St),
The motor is always placed under the proper load. In other words, the capacity of the hydraulic motor is set to be small within a range that can support the load torque, and therefore a high rotational speed can be obtained.

(Embodiment) In FIG. 1, reference numeral 1 denotes a drum of a mooring winch that winds up a mooring line 2, and this drum 1 is driven by a hydraulic motor 3. Reference numeral 4 is a reduction gear.

Reference numeral 5 denotes a hydraulic power supply source that maintains a substantially constant pressure and has sufficient capacity for the hydraulic motor 3. A flow control valve 6 is placed between the hydraulic source 5 and the hydraulic motor 3, which changes the flow rate and direction of the actuation 411, the rotational speed of the hydraulic motor 3, and thus the winch drum 1. It is designed to control direction. In addition, this flow 14
The control valve 6 is equipped with pressure compensation so that the flow rate changes only depending on the valve opening regardless of load fluctuations.

The hydraulic motor 3 may be of any type as long as its capacity can be changed continuously, but in this embodiment, a star-shaped radial plunger type variable capacity motor is used. code 7
is a hydraulic actuator connected to a drum (not shown) on which the piston rod slides, and when hydraulic pressure is selectively sent to the two hydraulic chambers, the drum eccentrically increases the motor capacity (required oil per rotation). is set to change continuously.

Reference numeral 8 designates an automatic switching valve that switches the direction of hydraulic pressure acting on the actuator 7, and its cross section is shown in FIG. . This valve 8 allows the spool 9 to move between two Ex-Dream positions A and B with a neutral position C in between. When the spool 9 is in the C position, no hydraulic pressure is sent to either boat of the actuator, so the motor displacement does not change. As the spool moves from the neutral position C towards the position, the pressure P will be sent through the boat The road becomes wider.

;φl This spool has a width of 3γ, and picks up 1 < and () 1. (FIG. 2 shows this state), the pressure P is sent to the boat 10 on the reduced capacity side of the actuator through the boat Y, and the closer it is to the position B, the wider the flow path becomes.

Code 12 is volume reduction! This is a spring that pushes the spool 9 toward the n position B, and its strength Fl can be adjusted with a screw 13.

Reference numeral 14 designates a pair of check valves, and the inlet pressure P of the motor 3 taken out through these check valves is applied to one end of the spool 9 of the switching valve, on the side without the spring 12 (the right end in FIG. 2), as a pilot pressure. It is acting as. A motor inlet side pressure P is applied to the other end of the spool 9 via a sequence valve I5. Note that the pressure receiving area at the end of the spool 9 is sl, assuming that the side without a spring is Sl and the side with a spring is S.
>St.

The pressure P of the sequence valve 15 is a set value P. It is closed when it is smaller than that, and opens when it becomes larger, which is the set pressure P. is the spring 17 pushing the spool 16
The strength can be adjusted by changing the screw I8.

In this embodiment, the hydraulic pressure to be sent to the actuator 7 is supplied from the inlet side of the motor, but it may be supplied directly from an external hydraulic pressure source.

Next, the effect will be explained. When the flow rate control valve 6 is opened while the motor 3 is stopped, hydraulic pressure is applied to the inlet side of the motor 3, and its value P becomes F , /S .

Become bigger. Then, the spring 12 contracts, the spool 9 moves, and the switching valve 8 switches to the capacity increase position A.
The actuator 7 increases the capacity of the motor 3. Generally, variable capacity motors cannot be started if the capacity is reduced to less than about 30% of the maximum value. However, since the motor capacity increases as soon as the flow control valve is opened, the motor is reliably started.

Next, when the flow rate control valve 6 is further opened and the rotation of the motor is increased, the load increases and the artificial side pressure (2) of the motor increases. The pressure P is the set pressure P of the sequence valve 15. When the pressure becomes higher, the sequence valve opens, pressure P acts on the opposite side of the spool 9, the switching valve 8 switches to the capacity reduction position B, and the actuator 7 reduces the capacity of the motor 3.

In this way, when the motor capacity decreases, the torque that can be generated decreases, so the load becomes relatively large and the pressure P
becomes higher. When the pressure P becomes larger than r;'+/(s+-5t), the spring 12 is compressed again, the spool moves, and the switching valve 8 is placed in the capacity increasing position. As the motor capacity increases, the torque that can be generated increases, so the load becomes relatively smaller and the pressure P decreases. Pressure Ph<
When it becomes smaller than FI/(Sl-8,), the switching valve 8 becomes the volume reduction M position B. In this way, the motor capacity is automatically controlled so that the pressure P is always equal to p+/(s, -s*), and therefore Fl/ If you adjust the values of (S, -S,),
The motor is always placed under the proper load. In other words, the capacity of the hydraulic motor is set to be small within a range that can support the load torque, and therefore a high rotational speed can be obtained.

The third section shows the characteristics of the mooring winch obtained in this way.
It is possible to operate within the hatched range by simply operating the flow E11 control valve.

(Effects) As explained above, according to the present invention, the capacity of the motor is always automatically set to a small value within the range that can support the load torque, so a high rotational speed can be obtained, and the rotational speed is controlled by the flow control valve. This has the effect of allowing you to freely control it from zero. Furthermore, since the motor capacity increases at the time of starting, there is also the effect that starting can be performed reliably.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and Fig. 1 is a drive circuit diagram of a hydraulic motor, Fig. 2 is a sectional view of a switching valve, and Fig. 3 is a sectional view of a switching valve.
The figure shows the characteristics of the winch. 3... Variable capacity type partial pressure motor 6... Flow rate control valve 7... Hydraulic actuator 8... Automatic switching valve 9... Spool 12... Sequence valve

Claims (1)

[Claims] 1. A variable displacement hydraulic motor equipped with a hydraulic actuator to change the motor capacity, a flow control valve to control the flow rate of hydraulic oil supplied to the motor, and a flow direction of the hydraulic oil acting on the actuator. The switching valve has a spring that pushes the valve spool to a position where the capacity of the motor is reduced, and one end of the spool, on the side without the spring, has a spring that pushes the valve spool to a position where the motor capacity is reduced. A hydraulic pressure P is applied to the inlet side of the motor, and the pressure P is applied to the other end of the spool via a sequence valve. is S_2, the set pressure of the sequence valve is P_0, and the repulsive force of the spring is F_1.
Then, F_1/S_1<P_0<F_1/(S_1
- A hydraulic motor drive circuit related to S_2).