JP2016132416A - Electro-hydraulic steering system using reversible-discharge-direction variable hydraulic pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electro-hydraulic steering system using a reversible-discharge-direction variable hydraulic pump for achieving prevention of chattering caused by simplification of a hydraulic circuit and suppression of heat generation.SOLUTION: An electro-hydraulic steering system includes: a rotary vane-type steering engine 10 that rotatively drives a steering wheel around the shaft center of a steering shaft 11; a reversible-discharge-direction variable hydraulic pump 20 that hydraulically drives the rotary vane-type steering engine 10; a three-phase induction motor 30 that electrically drives the reversible-discharge-direction variable hydraulic pump 20; and a control device 40 that controls bidirectional rotary drive of the three-phase induction motor 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to the technology of a marine vessel steering system (steering machine), in which a rotary vane type steering machine is hydraulically driven by a reversible discharge direction variable hydraulic pump (bidirectional discharge hydraulic pump), and a reversible discharge direction variable hydraulic pressure. The present invention relates to a technique of electro-hydraulic steering using a reversible discharge direction variable hydraulic pump in which a pump is electrically driven by a three-phase induction motor and the three-phase induction motor is inverter-controlled.

  As a conventional steering machine, there exists what was described in patent document 1, for example. The rotary vane steering machine includes a rotor in a housing, and includes a movable vane integral with the rotor and a segment integral with the housing, and the movable vane is disposed between the outer peripheral surface of the rotor and the inner peripheral surface of the housing. And a plurality of hydraulic oil chambers partitioned by segments.

  The characteristics required for such a steering machine are described below. FIG. 5 is a torque curve showing the relationship between the rudder angle of the rudder and the torque acting on the rudder shaft from the rudder. This torque curve shows an example of torque acting on the rudder shaft when the rudder plate is placed in running water.

  In general, in a range from a rudder angle of 0 ° to a certain rudder angle, the rudder plate is pushed by the water flow, the rudder shaft rotates, and the torque required to drive the rudder shaft becomes negative (−). When taking a large rudder angle exceeding the rudder angle, the rudder plate will not move unless positive (+) torque is applied to the rudder shaft.

  Conversely, when the rudder is returned to the 0 ° direction with respect to the water flow, the torque required to drive the rudder shaft by the rudder plate being pushed by the water flow until a certain rudder angle becomes negative (−). In order to turn the rudder plate in a neutral 0 ° direction beyond the angle, it is necessary to apply a positive (+) torque to the rudder shaft.

  However, the torque curve mentioned above is a static characteristic when the rudder angle is changed in the flow under the condition that the direction of the water flow is constant. As the hull changes its direction and the inflow angle of the water flow flowing into the rudder changes accordingly, the torque acting on the rudder shaft changes every moment.

  An example of a torque curve measured during trial operation of an actual ship is shown in FIG. The first curve shows the change in torque when steering from a neutral angle of 0 ° to the starboard direction (front rudder) at a rudder angle of 70 °, and the second curve shows a rudder at a rudder angle of 70 ° in the starboard direction. A change in torque is shown when steering is performed at a steering angle of 70 ° in the port direction (steering). The curve No. 3 shows the change in torque when steering a rudder at a steering angle of 70 ° in the starboard direction to the steering angle of 70 ° in the starboard direction, and the curve of No. 4 has a steering angle of 70 ° in the starboard direction. It shows the change in torque when a rudder is returned to 0 ° neutral.

  This torque curve is completely different from the torque curve shown in FIG. This is because the change of the inflow angle of the water flow to the rudder occurs due to the turning of the hull with steering. In FIG. 6, when the maximum rudder angle is reached, the reverse steering is performed. However, when the turning direction is reversed, the direction of the torque is reversed, at which point the curve suddenly jumps and the direction of the torque is reversed.

  For this reason, the torque applied to the rudder shaft changes in a complex manner from positive to negative to positive to negative. Steering machines are required to respond appropriately to such torques and can start from any position on these curves, without any overshoot or undershoot at any position according to the command from the autopilot. It must be able to stop correctly.

FIG. 7 shows an example of a conventional operation control hydraulic circuit that has been most frequently used in rotary vane type steering machines.
The rotary vane steering machine 50 includes a rotor 52 in a housing 51, and includes a movable vane 53 that is integral with the rotor 52 and a segment 54 that is integral with the housing 51. A plurality of hydraulic oil chambers 55 partitioned by a movable vane 53 and a segment 54 are formed between the peripheral surface and the peripheral surface.

  Then, the hydraulic oil in the hydraulic tank 58 is sent out by a one-way discharge pump 57 driven by the electric motor 56, and the destination of the hydraulic oil is set to the starboard side hydraulic oil chamber 55 and the port side hydraulic oil chamber by operating the electromagnetic switching valve 59. 55. Switch to unloading, rotate the rotor 52 in the starboard direction, rotate in the starboard direction, or switch to neutral.

Japanese Patent No. 5483976

  The hydraulic system described above is an open loop. Therefore, when the movable vane 53 is pushed by the hydraulic oil discharged from the one-way discharge pump 57 and the rotor 52 is rotated, a positive (+) torque is applied. Turn around.

  However, on the contrary, when turning in the direction in which the force from the rudder plate is received by the rudder shaft, negative (−) torque is applied. Therefore, if the flow regulator 60 is not provided, the pilot check valve 61 is accompanied by severe hydraulic shock and chattering. Will be caused.

  That is, when the discharge amount from the one-way discharge pump 57 is insufficient with respect to the rotation amount of the rotor 52, the hydraulic pressure of the hydraulic oil is lowered, and the return side valve of the pilot check valve 61 is closed due to the shortage of the pilot hydraulic pressure. Stops rotating. When the rotation of the rotor 52 is stopped, the hydraulic pressure of the hydraulic oil discharged from the one-way discharge pump 57 is increased, the pilot hydraulic pressure acting on the return side valve of the pilot check valve 61 is recovered, the return side valve is opened, and the rotor 52 is opened. Rotates again, and the return side valve is closed again for the reason described above. Chattering occurs by repeating the above-described event.

  For this reason, in order to alleviate the phenomenon that causes chattering, the flow of oil on the return side is throttled to increase the hydraulic pressure so that the opening and closing of the pilot check valve 61 does not occur as much as possible.

  However, excessively reducing the flow of oil on the return side causes a hydraulic pressure loss, so that the amount of restriction is moderate. Further, since the one-way discharge pump 57 is continuously operated, the oil temperature rises, and the hydraulic loss in the check valve 62 provided for raising the pilot hydraulic pressure of the electromagnetic switching valve 59 causes heat generation. It has become.

  Therefore, it is necessary to provide a large hydraulic tank 58 to cool the hydraulic oil to increase the heat radiation area, or to provide a cooling cooler, and this tendency increases especially as the steering machine has a higher output. .

  The present invention solves the above-described problems, and an object thereof is to provide an electric hydraulic steering system using a reversible discharge direction variable hydraulic pump that realizes prevention of chattering and suppression of heat generation by simplifying a hydraulic circuit. .

  In order to solve the above-mentioned problems, an electric hydraulic steering system using a reversible discharge direction variable hydraulic pump according to the present invention includes a rotary vane type steering machine for rotating a rudder around the axis of a rudder shaft, and a rotary vane type A reversible discharge direction variable hydraulic pump that hydraulically drives the steering gear, a three-phase induction motor that electrically drives the reversible discharge direction variable hydraulic pump, and a control device that controls bidirectional rotation drive of the three-phase induction motor It is characterized by that.

  In the electric hydraulic steering system using the reversible discharge direction variable hydraulic pump of the present invention, the rotary vane type steering machine has a steering angle signal transmitter, the control device has an inverter and a control circuit, The steering angle command signal input from the steering device for instructing the steering angle of the rudder and the steering angle signal input from the steering angle signal transmitter are collated to calculate the target turning direction, target turning angle, and target turning speed. And the normal / reverse rotation direction of the three-phase induction motor according to the target turning direction and the target operating frequency of the three-phase induction motor according to the target turning speed are calculated, and the inverter is the forward / reverse rotation direction indicated by the control circuit The phase rotation direction of the three-phase induction motor is controlled in accordance with the control signal, and the output voltage and output frequency output to the three-phase induction motor are controlled in accordance with the target operating frequency instructed from the control circuit.

  In the electrohydraulic steering system using the reversible discharge direction variable hydraulic pump of the present invention, the control circuit gradually increases the frequency instructed to the inverter from zero to the target operating frequency at the initial stage of the steering operation toward the target steering angle, At the end of the steering operation, the frequency instructed to the inverter is gradually decreased from the target operating frequency to zero.

  With the above-described configuration, the direction of rotation of the three-phase induction motor is controlled by forward / reverse reversal control to control the discharge direction of the hydraulic oil in the reversible discharge direction variable hydraulic pump to control the turning direction by the rotary vane type steering machine. .

  Therefore, there is no need for a check valve, flow control valve, electromagnetic switching valve, etc. to control the flow direction of hydraulic oil in the hydraulic circuit that supplies hydraulic oil to the rotary vane type steering machine. Can be formed.

  Therefore, the rudder rotates smoothly in the turning operation. Further, the temperature rise of the hydraulic oil due to hydraulic loss in the check valve, the flow rate control valve, etc. can be suppressed, and the reversible discharge direction variable hydraulic pump can be stopped except during the steering operation, so that the temperature rise for operation can be further suppressed. Therefore, a conventional hydraulic tank having an excessive heat radiation area is not required, and a small hydraulic tank can be used.

  The inverter controls the phase rotation direction of the three-phase induction motor according to the target turning direction, target turning angle, and target turning speed calculated by the control circuit, and controls the output voltage and output frequency output to the three-phase induction motor. Thus, the rotary vane type steering machine is steered by rotating the rudder shaft at the target turning direction, the target turning angle, and the target turning speed.

  In general, the starting current of a three-phase induction motor is 6 to 7 times the rated current. For this reason, when forward / reverse operation of the three-phase induction motor is performed frequently, if the forward / reverse reversal switching is frequently performed while maintaining the rated frequency, a large current region at the time of start is repeatedly generated. Generates heat and burns out the three-phase induction motor.

  However, in the present invention, the control circuit gradually increases the frequency instructed to the inverter at the initial stage of the steering operation from zero to the target operating frequency and gradually decreases the frequency instructed to the inverter at the end of the steering operation from the target operating frequency to zero. Further, it is possible to suppress an increase in starting current in the three-phase induction motor and to prevent overheating and burning of the three-phase induction motor. Also, the discharge oil amount of the reversible discharge direction variable hydraulic pump gradually increases at the initial stage of the steering operation, and the steering speed gradually increases. At the end of the steering operation, the discharge oil amount of the reversible discharge direction variable hydraulic pump Gradually decreases and the steering speed is gradually reduced, so that it is possible to prevent a hydraulic shock caused by abruptly switching the flow direction of the hydraulic oil by the electromagnetic switching valve as in the prior art.

FIG. 1 is a hydraulic circuit diagram of an operation control of a rotary vane type steering machine showing an embodiment of an electric hydraulic steering system using a reversible discharge direction variable hydraulic pump of the present invention. A graph showing the current torque curve of a three-phase induction motor Graph showing the relationship between the frequency of the supply voltage applied to the motor and the torque Graph showing the characteristics of a three-phase induction motor Graph showing the relationship curve between the rudder angle and the torque acting on the rudder shaft Graph showing the relationship between steering angle and rudder torque in an actual ship steering test Conventional operation control hydraulic circuit diagram

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 4, the electric hydraulic steering system of the present invention mainly includes a rotary vane type steering machine 10, a reversible discharge direction variable hydraulic pump 20, a three-phase induction motor 30, and a control device 40.

  The rotary vane type steering machine 10 rotates the rudder around the axis of the rudder shaft 11, includes a rotor 13 in a housing 12, a movable vane 14 integral with the rotor 13, and a housing 12 integral with the rotor 12. A plurality of hydraulic oil chambers 16 a, 16 b, 16 c, 16 d partitioned by a movable vane 14 and a segment 15 are formed between the outer peripheral surface of the rotor 13 and the inner peripheral surface of the housing 12. Yes. The housing 12 includes a collective valve (auto-lock valve) 17 at an outer position corresponding to each segment 15, and a rudder angle for detecting the current rudder angle of the rudder in conjunction with the rotation of the anti-shock valve 18 and the rudder shaft 11 on one side. A signal transmitter 19 is provided.

  Hereinafter, the operation control hydraulic circuit connected to the hydraulic oil chambers 16a and 16b will be described, but the operation control hydraulic circuit connected to the hydraulic oil chambers 16c and 16d is the same. A reversible discharge direction variable hydraulic pump (bidirectional discharge hydraulic pump) 20 supplies hydraulic oil to the rotary vane type steering machine 10 and hydraulically drives the rotor 13 by the hydraulic pressure, and the three-phase induction motor 30 is acceptable. The reverse discharge direction variable hydraulic pump 20 is electrically driven.

  A hydraulic circuit 100 is provided between the reversible discharge direction variable hydraulic pump 20 and the collective valve 17 of the rotary vane type steering machine 10. The hydraulic circuit 100 includes a closed loop pipe line 103 and a closed loop pipe line 103 communicating between the discharge ports 101 and 102 of the reversible discharge direction variable hydraulic pump 20 and the collective valve 17 of the rotary vane steering gear 10. In addition, a head tank 106 communicating with the relief valve 104 and the check valve 105 is provided. The relief valve 104 guides hydraulic oil to the head tank 106 when the pressure in the closed loop pipe line 103 becomes equal to or higher than the set pressure, The stop valve 105 guides the hydraulic oil from the head tank 106 when the hydraulic oil in the closed loop conduit 103 is insufficient.

  The control device 40 controls the bi-directional rotational drive of the three-phase induction motor 30, and includes an inverter 41 and a control circuit 42, and includes a power line 43 and a steering angle command signal line 44 for a steering device (autopilot). The steering angle signal line 45 of the steering angle signal transmitter 19 is connected.

  The control circuit 42 receives the steering angle command signal input from the steering device for instructing the steering angle of the rudder via the steering angle command signal line 44, and the rudder input from the rudder angle signal transmitter 19 via the steering angle signal line 45. The target turning direction, the target turning angle, and the target turning speed are calculated by comparing with the angle signal, and the forward / reverse rotation direction and the target turning speed of the three-phase induction motor 30 according to the target turning direction are calculated. The target operation frequency of the corresponding three-phase induction motor 30 is calculated.

  The inverter 41 controls the phase rotation direction of the three-phase induction motor 30 in accordance with the forward / reverse rotation direction instructed from the control circuit 42 and outputs to the three-phase induction motor 30 in accordance with the target operating frequency instructed from the control circuit 42. Control output voltage and output frequency.

  Further, the control circuit 42 gradually increases the frequency instructed to the inverter 41 from zero to the target operating frequency at the initial stage of the steering operation toward the target steering angle, and sets the frequency instructed to the inverter 41 at the end of the steering operation. Gradually decrease from zero to zero.

  Hereinafter, the operation of the above configuration will be described. In the turning operation, a steering angle command signal is input from the operating device to the control device 40 via the steering angle command signal line 44, the three-phase induction motor 30 is controlled by the control device 40, and the reversible discharge direction variable hydraulic pump 20. Is driven by a three-phase induction motor 30 to supply hydraulic oil to the rotary vane type steering machine 10 to drive the rudder shaft 11 directly connected to the rotary vane type steering machine 10 to move the steering plate. Steer by.

  The control circuit 42 of the control device 40 includes a command turning angle input as a steering angle command signal from the steering device via the steering angle command signal line 44, and a rudder from the steering angle signal transmitter 19 via the steering angle signal line 45. The current rudder angle input as an angle signal is collated. Then, the target steering direction is calculated as to whether the rudder shaft 11 is rotated in the surface steering direction or the steering direction, and the necessary rotation angle of the rudder shaft 11 is determined from the difference between the command steering angle and the current steering angle. And an appropriate turning speed commensurate with the ship speed or the like is calculated as the target turning speed.

  Furthermore, the control circuit 42 calculates the discharge direction of the hydraulic oil of the reversible discharge direction variable hydraulic pump 20 necessary for rotating the rotary vane type steering machine 10 in the target steering direction, and the hydraulic oil is output in this discharge direction. The forward and reverse rotation directions of the three-phase induction motor 30 necessary for supplying the motor are calculated. Further, the required amount of oil for driving the rotary vane type steering machine 10 at a speed corresponding to the target turning speed is calculated, and the required number of rotations of the reversible discharge direction variable hydraulic pump 20 necessary for sending this required amount of oil. And the target operating frequency of the three-phase induction motor 30 necessary for rotating the reversible discharge direction variable hydraulic pump 20 at this required rotational speed is calculated.

  The inverter 41 controls the phase rotation direction of the three-phase induction motor 30 in accordance with the forward / reverse rotation direction instructed from the control circuit 42 and outputs to the three-phase induction motor 30 in accordance with the target operating frequency instructed from the control circuit 42. Control output voltage and output frequency.

  As the three-phase induction motor 30 rotates in this phase rotation direction, output voltage, and output frequency, the reversible discharge direction variable hydraulic pump 20 supplies the required amount of oil to the rotary vane type steering machine 10 in an appropriate discharge direction. The rudder shaft 11 directly connected to the rotary vane type steering machine 10 is driven at the target turning speed to move the rudder plate.

These calculations and operations are appropriately performed as needed based on a difference signal that changes every moment between the steering angle command signal and the steering angle signal.
When the difference between the steering angle command signal from the steering device (autopilot) and the steering angle signal from the steering angle signal transmitter 19 becomes zero, the control circuit 42 controls the output voltage and output frequency of the inverter 41 to zero. . That is, by setting the output frequency to zero, the three-phase induction motor 30 is stopped, the reversible discharge direction variable hydraulic pump 20 is stopped, the hydraulic oil discharge amount is set to zero, and the rotary vane type steering machine 10 is stopped. .

  Further, the control circuit 42 gradually increases the frequency instructed to the inverter 41 from zero to the target operating frequency at the initial stage of the steering operation toward the target steering angle, and the three-phase induction motor 30 and the reversible discharge direction variable hydraulic pump 20. Slowly increase the rotation of As a result, the amount of hydraulic fluid discharged from the reversible discharge direction variable hydraulic pump 20 gradually increases, and the turning speed gradually increases to the target turning speed.

  At the end of the steering operation, the frequency instructed to the inverter 41 is gradually decreased from the target operating frequency to zero, and the rotations of the three-phase induction motor 30 and the reversible discharge direction variable hydraulic pump 20 are gradually decreased. As a result, the amount of hydraulic oil discharged from the reversible discharge direction variable hydraulic pump 20 gradually decreases, the turning speed gradually decreases to zero, and the rudder stops.

  As described above, in this embodiment, the rotational direction of the three-phase induction motor 30 is controlled to be forward / reversely reversed to control the discharge direction of the hydraulic oil of the reversible discharge direction variable hydraulic pump 20 to thereby control the rotary vane type steering machine. By controlling the steering direction by 10, a check valve, a flow control valve, an electromagnetic switching valve and the like for controlling the flow direction of the hydraulic oil in the hydraulic circuit 100 that supplies the hydraulic oil to the rotary vane type steering machine 10 are provided. It becomes unnecessary and a closed loop can be formed with a simple hydraulic circuit 100.

  The closed-loop hydraulic circuit configured between the reversible discharge direction variable hydraulic pump 20 and the rotary vane type steering machine 10 is a load of the steering machine, that is, from positive (+) torque to negative (-) torque. The direction changes at random, and the size of the rudder functions extremely effectively against a load that changes at random, and the rudder rotates smoothly in the turning operation.

  That is, when the rotary vane type steering machine 10 is steered while receiving a positive (+) torque from the rudder, the reversible discharge direction variable hydraulic pump 20 generates a hydraulic pressure corresponding to the torque to generate the rotary vane type steering. The rudder shaft 11 is rotated by giving to the machine 10. The steering operation under the action of the positive (+) torque can be performed without any trouble even in an open loop.

  However, in the open loop, when the rotary vane type steering machine 10 receives a large negative (−) torque from the rudder, the amount of hydraulic oil returned from the rotary vane type steering machine 10 to the oil tank is reduced from the hydraulic pump to the rotary loop. More than the discharge amount of the hydraulic oil supplied to the vane type steering machine 10, the discharge amount of the hydraulic pump is insufficient with respect to the rotation of the rotor 13, and a negative pressure is generated on the entry side of the rotary vane type steering machine 10. . For this reason, as described above, in an open loop hydraulic control circuit in which an electromagnetic switching valve and a pilot check valve are combined, a chattering phenomenon accompanied by a hydraulic shock occurs. In order to reduce this chattering phenomenon, a flow regulator is unavoidably provided with a hydraulic loss to increase the resistance on the outlet side of the rotary vane type steering machine 50. The output will be reduced.

  On the other hand, in the closed loop hydraulic circuit of the present invention, the hydraulic oil returns from the rotary vane type steering machine 10 to the reversible discharge direction variable hydraulic pump 20, and therefore negative (− ) When the hydraulic fluid returns to the reversible discharge direction variable hydraulic pump 20 when torque is applied, the reversible discharge direction variable hydraulic pump 20 acts as a hydraulic motor to accelerate the three-phase induction motor 30. To work.

  By this action, if the three-phase induction motor 30 exceeds the synchronous speed, it functions as a generator, and by collecting this electric power by the inverter 41, a braking force is generated on the rotating shaft of the three-phase induction motor 30. By controlling the increase in the rotational speed of the three-phase induction motor 30 and the reversible discharge direction variable hydraulic pump 20 with this braking force, the flow of hydraulic oil is suppressed to a flow rate corresponding to the rotational speed of the reversible discharge direction variable hydraulic pump 20. Thus, it is possible to prevent the rotary vane type steering machine 10 from being hydraulically driven at an excessive speed.

  A current torque curve of an induction motor that generally performs inverter control is shown in FIG. The starting current is very large and is usually 6-7 times the rated current. As the rotational speed increases, the current value decreases and becomes almost zero at the synchronous speed. Normally, the starting torque is about 200% of the rated torque, and reaches a maximum torque called stationary torque at a certain rotational speed, and becomes zero at the synchronous rotational speed. The rated rotational speed is a rotational speed larger than the stationary torque speed and smaller than the synchronous speed, and the torque is in a drooping characteristic region.

  Therefore, when operated in such a region, the operation is very responsive and stable with respect to load fluctuations. However, if this motor is rotated forward and backward frequently, the current becomes very large in the region where the rotational speed is low, and if the rotor with large inertia repeats forward and reverse rotation, The motor windings will soon heat up and burn out.

Therefore, the induction motor is not suitable for use in an operation in which forward and reverse rotations are repeatedly performed while the applied voltage and frequency to the induction motor are kept constant.
On the other hand, since the steering machine performs the right steering and the left steering frequently and repeatedly, the three-phase induction motor 30 is used when the rotary vane type steering machine 10 is hydraulically driven by the reversible discharge direction variable hydraulic pump 20. Is not suitable for the reason that an excessive current flows from the start until the rated rotational speed is reached after the application voltage and frequency are kept constant.

  In general, an inverter is used for controlling the rotational speed by repeatedly changing the frequency applied to the induction motor. By changing the frequency with the inverter and adding the excitation current to the output voltage proportional to the frequency, as shown in Fig. 3, any starting torque, constant torque, load torque (rated) The same can be applied to the frequency, and the current value basically does not change for the same load torque.

  By performing such control, the rotation speed can be freely changed while keeping the load torque and current of the motor within a certain range. In the present invention, this control characteristic is used to perform forward / reverse operation of the reversible discharge direction variable hydraulic pump 20.

  Conventionally, induction motors could not perform forward / reverse operation, as described above, when forward / reverse switching operation is performed under a constant frequency, the current flowing to the motor becomes excessive in the region where the rotation speed is low, In general, the starting current of a three-phase induction motor is 6 to 7 times the rated current. For this reason, when forward / reverse operation of the three-phase induction motor is performed, if the forward / reverse reversal switching is frequently performed with the rated frequency maintained, a large current region is repeatedly generated at the start of forward / reverse reversal. Excessive heat generation occurs, leading to burnout of the three-phase induction motor.

  However, the control circuit 42 gradually increases the frequency instructed to the inverter 41 at the initial stage of the steering operation from zero to the target operating frequency, thereby gradually increasing the rotation of the three-phase induction motor 30 and the reversible discharge direction variable hydraulic pump 20. The turning speed gradually increases to the target turning speed, and the frequency instructed to the inverter 41 at the end of the turning operation is gradually reduced from the target operating frequency to zero, so that the three-phase induction motor 30 and the reversible discharge direction variable hydraulic pump 20 By gradually reducing the rotation, the steering speed is gradually lowered to zero and the rudder stops. Therefore, an increase in starting current in the three-phase induction motor 30 is suppressed, and overheating and burning of the three-phase induction motor 30 are prevented. it can.

  Further, the amount of oil discharged from the reversible discharge direction variable hydraulic pump 20 is gradually increased at the initial stage of the steering operation, and the steering speed is gradually increased. At the end of the steering operation, the discharge of the reversible discharge direction variable hydraulic pump 20 is performed. Since the oil amount is gradually reduced and the turning speed is gradually reduced, the hydraulic shock caused by suddenly switching the flow direction of the hydraulic oil by the electromagnetic switching valve as in the conventional case can be prevented. The take-up machine 10 can be smoothly steered without causing chattering, and can be operated without causing hydraulic shock.

  In addition, it is possible to suppress the temperature rise of the hydraulic oil due to hydraulic loss in the check valve, the flow control valve, etc., and to further suppress the temperature rise of the hydraulic oil because the reversible discharge direction variable hydraulic pump 20 can be stopped except during the steering operation. Therefore, a conventional hydraulic tank having an excessive heat radiation area is not required, and a small hydraulic tank can be used.

  Moreover, in the conventional hydraulic control system in which the one-way discharge pump is driven with a constant voltage and low-frequency power source by an induction motor and the discharge direction is switched by an electromagnetic switching valve as in the prior art, the electric motor can be used even when the steering operation is not performed. It was necessary to keep driving continuously, and wasted wasted power all the time.

  However, in the present invention, at the neutral time when the vehicle is not steered, the reversible discharge direction variable hydraulic pump 20 and the three-phase induction motor 30 are stopped, so that no electric power is consumed and the energy can be saved. In addition, since the hydraulic oil is not overheated, a simple cooling device can be used, and the temperature rise of the hydraulic oil can be easily kept low, so that deterioration of the sealing material in the hydraulic equipment can be suppressed.

  FIG. 4 shows the characteristics of the three-phase induction motor 30. The three-phase induction motor 30 is normally used in an electric range. In this region, current is sent from the power source to the three-phase induction motor 30, and the motor is driven to generate torque corresponding to the load to move the load object. When the three-phase induction motor 30 is rotated at a speed exceeding the synchronous speed by an external force, it is used in the power generation area. The electric power generated by the three-phase induction motor 30 acting as a generator is returned to the power source or becomes heat by a separately provided resistor.

  In any case, since the energy applied from the outside is absorbed by this power generation, even when the torque due to the external force acts on the rotary vane type steering machine 10, the rotor 13 is prevented from being rotated at an excessive speed. Can do.

  The braking area is used, for example, in the case of sudden reverse rotation during starboard turning, but this area should be avoided as much as possible. In the case of reverse rotation, the output frequency of the inverter 41 is lowered to lower the motor rotation speed, and when the steering speed becomes almost zero, phase switching is performed to reverse rotation.

  The check valve 105, the relief valve 104, and the head tank 106 in FIG. 1 are moved in and out of the rotary vane type steering machine 10 due to expansion and contraction of hydraulic oil due to changes in the amount of hydraulic oil and external force received from the rudder. When there is a difference in the flow rate of hydraulic fluid between the two sides or when an oil leak occurs in the hydraulic circuit for some reason, the hydraulic fluid is supplied to the buffering function or the hydraulic circuit.

  For example, when the rotor 13 of the rotary vane type steering machine 10 is rotating in the steering direction, a negative torque acts on the rudder shaft 11 from the rudder, and the rotor 13 is excessively rotated in the same direction, so that a large amount of hydraulic oil. When a large amount of oil is expelled, this large amount of oil has no place to go inside the closed loop conduit 103, resulting in an abnormal increase in hydraulic pressure.

  In such a case, the balance of the flow of the hydraulic oil is adjusted by flowing excess oil from the relief valve 104 to the head tank 106. At this time, within the range where the hydraulic pressure does not reach the relief pressure, as described above, the reversible discharge direction variable hydraulic pump 20 functions as a hydraulic motor, the three-phase induction motor 30 functions as a generator, and brakes while returning power to the power source. Force acts.

  The check valve 105 supplies the hydraulic oil to the hydraulic line when the hydraulic oil is insufficient in the closed loop line 103. In this way, the amount of hydraulic oil is balanced in the closed loop hydraulic circuit.

  In FIG. 1, a collective valve 17 provided in the rotary vane type steering machine 10 is a kind of auto-lock valve that is a pilot check valve, and the rotary vane type steering machine 10 is driven by a reversible discharge direction variable hydraulic pump 20. In the case where the external piping is damaged, however, the reversible discharge direction variable hydraulic pump 20 on the damaged side is stopped and the operation is continued with the healthy reversible discharge direction variable hydraulic pump 20 on the sound side. It is provided.

  In other words, the auto-lock valve has a structure in which the inlet and outlet ports open at the pump discharge pressure at the same time and hydraulic fluid flows, and if there is no pump discharge pressure, it closes and shuts off the oil flow. Accordingly, the oil can be prevented from flowing out from the place where the oil is discharged, and the operation can be performed by the reversible discharge direction variable hydraulic pump 20 on the sound side.

DESCRIPTION OF SYMBOLS 10 Rotary vane type steering machine 11 Rudder shaft 12 Housing 13 Rotor 14 Movable vane 15 Segment 16a, 16b, 16c, 16d Hydraulic oil chamber 17 Collecting valve 18 Anti-shock valve 19 Steering angle signal transmitter 20 DESCRIPTION OF SYMBOLS 30 Three-phase induction motor 40 Control apparatus 41 Inverter 42 Control circuit 43 Power supply line 44 Steering angle command signal line 45 Steering angle signal line 100 Hydraulic circuit 101,102 Discharge port 103 Closed loop pipe line 104 Relief valve 105 Check valve 106 Head tank

Claims (3)

  A rotary vane type steering machine that rotates the rudder around the axis of the rudder axis, a reversible discharge direction variable hydraulic pump that hydraulically drives the rotary vane type steering machine, and a reversible discharge direction variable hydraulic pump that is electrically driven An electric hydraulic steering system using a three-phase induction motor and a control device for controlling bidirectional rotational drive of the three-phase induction motor using a reversible discharge direction variable hydraulic pump. The rotary vane type steering machine has a rudder angle signal transmitter, the control device has an inverter and a control circuit,
The control circuit collates the steering angle command signal input from the steering device for instructing the steering angle of the rudder and the steering angle signal input from the steering angle signal transmitter to check the target turning direction, target turning angle, target turning Calculate the speed, calculate the forward / reverse rotation direction of the three-phase induction motor according to the target turning direction, the target operating frequency of the three-phase induction motor according to the target turning speed,
The inverter controls the phase rotation direction of the three-phase induction motor in accordance with the forward / reverse rotation direction instructed from the control circuit, and outputs the output voltage and output to the three-phase induction motor in accordance with the target operating frequency instructed from the control circuit. The electric hydraulic steering system using the reversible discharge direction variable hydraulic pump according to claim 1, wherein the frequency is controlled.   The control circuit gradually increases the frequency instructed to the inverter from zero to the target operating frequency at the beginning of the steering operation toward the target turning angle, and gradually decreases the frequency instructed to the inverter from the target operating frequency to zero at the end of the steering operation. An electric hydraulic steering system using the reversible discharge direction variable hydraulic pump according to claim 2.

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