JPS62237101A - Driving circuit for hydraulic motor - Google Patents

Abstract

PURPOSE:To simplify the structure of a driving circuit and to facilitate operation by feedback controlling the capacity of a motor to keep load pressure of the motor substantially constant. CONSTITUTION:A flow control valve 6 is disposed between a hydraulic power source 5 and a hydraulic motor 3, and a directional control valve 8 is disposed between a hydraulic cylinder 7 for varying the capacity of the hydraulic motor 3 and a check valve 11 connected to a driving circuit of the hydraulic motor 3. A hydraulic cylinder 10 of the directional control valve 8 is connected to the check valve 11, and a hydraulic cylinder 15 is connected to a directional control valve 12. In this arrangement, the capacity of the hydraulic motor 3 can be feedback controlled to keep the load pressure of the hydraulic motor 3 substantially constant, the capacity of the hydraulic motor 3 can be automatically set small within the range bearing the load,and further the rotating speed can be freely controlled from zero by the flow control valve 6. Accordingly, the structure can be simplified and operation can be facilitated.

Description

[Detailed description of the invention]

[Field of Industrial Application] This invention relates to a drive circuit for a hydraulic motor suitable for the drive section of a mooring winch.

[Prior Art] The rotational speed of a mooring winch does not need to be high when the load is large, that is, when pulling a ship to a quay, but it needs to be sufficiently high when winding out or reeling a mooring line with a light load. required. This is to speed up the mooring work, and also to prevent the mooring line from becoming tangled in the propeller by winding it up at high speed when leaving the berth. Such winch characteristics can be obtained by converting the hydraulic motor to constant horsepower, but the conventional constant horsepower drive circuit is based on the capacity of the variable displacement hydraulic motor (i.e., the amount of oil required per motor revolution ff1). As the capacity is reduced, the torque will decrease and the rotational speed will increase while the horse power remains constant.

[Problems 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 reduced. 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 this invention is to obtain a constant horsepower MwJ circuit for a hydraulic motor that is simple to purchase and easy to operate.

[Means for Solving the Problems] A hydraulic motor drive circuit according to the present invention includes a variable displacement hydraulic motor and a flow rate controller placed between the hydraulic motor and a hydraulic power supply source to control the rotation speed of the hydraulic motor. It has a valve and a motor capacity control section that performs feedback control of the capacity of the motor so that the load pressure of the hydraulic motor is kept constant.

[Operation] In a hydraulic motor, when the load becomes heavy, the load pressure of the hydraulic motor (that is, the oil pressure on the inlet side of the hydraulic motor) increases, and when the load becomes light, the load pressure decreases. The motor capacity control wJ section increases the capacity of the hydraulic motor when the load is too heavy (that is, when the motor load pressure is greater than a reference value). As the capacity of the motor increases, the torque that can be generated also increases, the load becomes relatively smaller, and the load pressure on the motor decreases. Conversely, when the load is too light, the motor capacity control section reduces the capacity of the motor. In this way, the motor capacity controller controls the motor quantity so that the motor load pressure always matches the reference value, so that the motor is always properly loaded. In other words,
The hydraulic motor is designed to have a large capacity within a range that can support the load torque, and therefore a high rotational speed can be obtained. On the other hand, by operating the flow control valve, the amount of oil supplied to the hydraulic motor can be changed, and the rotational speed of the hydraulic motor can be continuously controlled from zero to an upper limit speed determined by the motor capacity at that time.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, 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 maintains a substantially constant pressure, and the hydraulic motor 3
It is a hydraulic power supply source with sufficient capacity for A flow control valve 6 is placed between the hydraulic power source 5 and the hydraulic motor 3, which changes the flow rate and direction of the hydraulic oil, and controls the hydraulic motor 3,
Therefore, the rotation speed and rotation direction of the winch drum 1 are controlled. Note that this flow control valve 6 is
Types with pressure compensation are used so that the flow rate changes only depending on the valve opening regardless of load fluctuations. The hydraulic motor 3 can 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, and this type of motor has a piston rod. The drum (not shown) to which it is attached is made eccentric from the rotating shaft to change the capacity fi (required oil ff1 per rotation). Reference numeral 7 is a hydraulic cylinder for changing the eccentricity, or capacity, of the motor 3. When hydraulic pressure is selectively sent to the two hydraulic boats, the pump capacity changes continuously between the maximum value and the minimum value. do. Next, the motor capacity control section will be explained. Reference numeral 8 is a switching valve that switches the operating oil pressure to the hydraulic cylinder 7. In this valve, the spool is biased in one direction by a spring 9, and a hydraulic cylinder 10 is provided in order to move the spool in the opposite direction against this bias. Reference numeral 11 is a check valve, and the motor load pressure taken out through this is sent to the hydraulic cylinder 10 as pilot pressure for the switching valve 8. In this embodiment, the operating oil pressure for the hydraulic cylinder 7 is taken from the motor load pressure, but it may be supplied from another external oil pressure source. Suppose that the load on the hydraulic motor 3 becomes heavier (or lighter) during operation. If this happens, the motor load pressure will be high.
(lower) to overcome (lose) the force of the spring 9, and the switching valve 8 is switched from the green coffee position to the left position (right position). Then, hydraulic pressure enters the inner oil chamber 7a (outer oil chamber 7b) of the hydraulic cylinder 7, and the capacity of the motor 3 increases (decreases). In this case, the torque that can be generated increases (decreases), so the load becomes relatively small (increases), and the motor load pressure decreases (J: increases). In this way, the load pressure of the motor eventually becomes balanced with the force of the spring 9, the valve 8 returns to the green coffee position, and the motor capacity no longer changes. In this way, the motor capacity control section changes the motor capacity according to the load torque, and performs control so that the highest rotational speed can be obtained with the load at that time. In addition, by changing the opening degree of the flow control valve 6, the amount of hydraulic pressure supplied to the hydraulic motor 3 can be divided, so the rotation speed of the mooring winch can be continuously controlled from zero to the maximum speed that can be obtained under the load at that time. It can be changed. The second part 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 rate control valve 6. By the way, the star-shaped radial motor 3 cannot self-start if the capacity is reduced to 30% or less of the maximum value. Therefore, if the maximum/11 capacity of the motor 3 is set to 30% or less, a separate starting means is required. For this reason, this embodiment has a switching valve 12. This valve has a spool that
It follows the cam 14 provided on the handle 13 of the flow rate control valve 6 to encourage it. Further, the switching valve 8 is provided with a second cylinder 15, which is connected to the hydraulic pressure source 5 via the switching valve 12. When the handle 13 is in neutral or slightly tilted forward or backward, the switching valve 12 is in the upper position (the position shown), so hydraulic pressure enters the cylinder 15, and the switching valve 8 is in the left position regardless of the motor load. , the motor capacity is set to maximum. Therefore, a large torque can be obtained when starting the winch, and starting can be performed reliably. Further, when the handle 13 is tilted back and forth, the switching valve 12 is switched to the lower position by the cam 14, and the cylinder 15
The hydraulic pressure is released, and the valve 8 returns to its original state of operating under the motor load pressure.

[Effects] According to the present invention, as explained above, the capacity of the motor is set to a small self-excitation range within the range that can carry the load, and therefore a high rotational speed can be obtained, and the rotational speed is zeroed by the flow control valve. This has the effect of being able to be controlled freely.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a drive circuit diagram of a hydraulic motor, and the second section is a characteristic diagram obtained by the circuit shown in FIG. 1.

Claims (1)

[Claims] 1. A variable displacement hydraulic motor, a flow control valve placed between the motor and a hydraulic supply source to control the rotational speed of the motor, and a flow control valve placed so that the load pressure of the motor is approximately constant. A hydraulic motor drive circuit having a motor capacity control section that performs feedback control of the motor capacity.