JP2004284574A - Power steering device for small craft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device for a small craft easily operatable with small steering force without concerns about waterproof property. <P>SOLUTION: This power steering device comprises a gear device 4 that drives a link mechanism for turning and steering an outboard motor body as a steering means at the rear side of the craft body through a push-pull cable by a steering handle 2 at a driver's seat side. A torque sensor 35 detects the steering torque input into the gear device 4 by the steering handle 2, and the gear device 4 assists the drive in the steering operation direction by means of an electric motor 27, a worm gear 25 and a worm wheel 26. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power steering apparatus for small boats, in which steering of an outboard motor and a rudder is assisted by an electric motor.

  2. Description of the Related Art As a power steering device of a boat with an outboard motor, a technique of power assisting with an electric motor has been conventionally proposed (see Patent Document 1).

This is configured so that the operation of the steering wheel disposed in the driver's seat is transmitted to an outboard motor that is steerably supported at the rear of the boat via a wire, and the outboard motor is rotated according to the steering amount of the steering wheel. On the other hand, there is provided a power assist mechanism for rotating the outboard motor through the reduction gear using the rotational force of the electric motor. The assisting force of the electric motor is controlled by an electronic control unit (ECU) according to an output signal of a steering force sensor for sensing a steering transmission force acting on the wire portion, an engine speed signal of the outboard motor, and the like. .
Patent No. 2652788

  However, in the above conventional example, since the electric motor and the steering force sensor are arranged near the outboard motor, it is necessary to increase waterproofness so that water scattered from a propeller or the like does not enter. There has been a problem that the mounting is complicated and the product cost is increased.

  In addition, since a steering force sensor that senses the force of the wire that is pushed and pulled by steering the steering wheel is used, the steering force that can be sensed due to friction associated with the operation decreases / changes, and the accuracy decreases. As a result, there is a problem in that the assist force is suppressed, and there is a limit in reducing the steering force and improving the feeling.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an inexpensive small boat power steering device that is easy to operate with a light steering force and good feeling without considering waterproofness. .

  According to a first aspect of the present invention, there is provided a steering device arranged at a rear portion of a hull so as to be rotatable in a horizontal direction, a link mechanism for turning and steering the steering device at a rear portion of the hull, a gear device which is steered by a steering handle of a driver's seat, Connecting means for transmitting the output of the gear device to the link mechanism; a torque sensor for detecting a steering torque input to the gear device from a steering handle; and assisting the gear device in a steering operation direction at least according to a detection signal of the torque sensor. It is characterized by comprising an electric actuator to be driven, and a controller to take in the detection signal of the torque sensor, calculate and drive the electric actuator. As the steering means, there is an outboard motor having a built-in rudder or propulsion device rotatably disposed at the rear of the hull.

  A second invention is characterized in that, in the first invention, the gear device, the torque sensor, and the electric actuator are integrally connected and assembled.

  According to a third invention, in the first or second invention, the electric actuator is connected to the gear device via a clutch device.

  In a fourth aspect based on the first to third aspects, the connecting means comprises two push-pull cables having the same configuration.

  According to a fifth aspect of the present invention, the controller outputs basic assist force determining means for calculating a basic assist force signal of the electric actuator according to a detection signal of the torque sensor, and outputs a final assist force signal of the electric actuator according to the basic assist force signal. And an auxiliary assist force determining means for differentiating the detection signal of the torque sensor, outputting a differential term thereof, and outputting a correction signal for suppressing a change in the assist force of the electric actuator.

  In a sixth aspect, the basic assist force determining means of the fifth aspect is provided with a plurality of output characteristics of the basic assist force signal and selects one of them or changes the output characteristic of the basic assist force signal. Means for changing an output characteristic of the basic assist force signal in accordance with an external changeover switch or a propulsion state such as a boat speed.

  According to a seventh aspect, the assisting force determining means of the fifth or sixth aspect adds the correction signal to the basic assisting force signal and / or the final assisting force signal to suppress a change in the assisting force of the electric actuator. Configured.

  In an eighth aspect based on the fifth to seventh aspects, the controller determines the turning back state of the steering handle from the output signal of the torque sensor and the rotation direction of the electric actuator, and increases the basic assist force signal in the turning back direction. It is configured to have a return control means for causing the return.

  In a ninth aspect based on the fifth to eighth aspects, the controller is provided with convergence control means for suppressing the basic assist force signal in accordance with the operation speed of the electric actuator.

  In a tenth aspect, the output signals of the return control means and the convergence control means of the eighth or ninth aspect are adjusted in accordance with the boat speed.

  Therefore, the first invention includes a gear device that drives a link mechanism for turning and steering the steering means at the rear part of the hull by the driver's seat side steering handle via the connecting means, and the steering torque input to the gear device by the steering handle. Is detected by the torque sensor and the gear device is assisted by the electric actuator in the steering operation direction. Therefore, the electric actuator and the torque sensor are attached to the steering shaft and the gear device directly operated by the steering handle of the driver's seat. It can be arranged, it is not necessary to consider the intrusion of water scattered from a propeller of an outboard motor or the like as a steering means, there is no increase in product cost such as enhancing waterproofness, and it can be provided at low cost. . In addition, the torque sensor does not include friction such as wires, and can directly detect the steering force of the driver, so that the steering torque can be detected with high accuracy, and the assist force of the electric motor that is calculated and driven by the ECU is increased. As a result, the steering force can be reduced, and the friction feeling is not included, so that the steering feeling can be improved.

  According to the second aspect, in addition to the effects of the first aspect, the gear device, the torque sensor, and the electric actuator are integrally assembled and assembled, so that the cost can be further reduced and the handling thereof is facilitated.

  In the third invention, in addition to the effects of the first or second invention, the electric actuator is connected to the gear device via the clutch device, so that the electric motor can be separated and free by the clutch portion. . For this reason, in the event of a device failure, power supply failure, etc., the clutch device is released and the electric motor is not used as a load, and the steering device operates the gear device, the coupling device, and the link mechanism to manually steer the steering device. can do.

  In the fourth aspect, in addition to the effects of the first to third aspects, since the connecting means is constituted by two push-pull cables having the same configuration, it is possible to transmit a high driving force, and the power is assisted by the electric motor. The transmitted driving force can be optimally transmitted to the link mechanism.

  In the fifth invention, a controller outputs basic assist force determining means for calculating a basic assist force signal of the electric actuator according to a detection signal of the torque sensor, and outputs a final assist force signal of the electric actuator according to the basic assist force signal. A servo amplifier processing means for performing the operation, and an auxiliary assist force determining means for differentiating the detection signal of the torque sensor and outputting a differential term thereof to output a correction signal for suppressing the fluctuation of the assist force of the electric actuator. Output fluctuations due to the cogging torque and the phase lag are suppressed, and the steering feeling can be improved.

  In a sixth aspect, the basic assist force determining means of the fifth aspect is provided with a plurality of output characteristics of the basic assist force signal, and selects one of the output characteristics or changes the output characteristic of the basic assist force signal. Means to change the output characteristic of the basic assist force signal according to the external changeover switch or the propulsion state such as the boat speed, etc., so that an optimal steering feeling can be obtained according to the running conditions such as the boat speed of a small boat. Can be.

  According to a seventh aspect, the assisting force determining means of the fifth or sixth aspect adds the correction signal to the basic assisting force signal and / or the final assisting force signal so as to suppress a variation in the assisting force of the electric actuator. With this configuration, the correction signal can be added to the final assist signal without being canceled by the integration processing by the servo amplifier processing means, and the fluctuation of the assist force of the electric actuator can be effectively suppressed.

  According to the eighth aspect, the controller includes a return control unit that determines the turning back state of the steering handle from the output signal of the torque sensor and the rotation direction of the electric actuator and increases the basic assist force signal in the turning back direction. When switching back to right steering to return from straight steering to left steering (and vice versa), it is possible to improve the state in which the steering wheel becomes difficult to return due to friction or inertia of the electric motor.

  In the ninth aspect, the controller is provided with the convergence control means for suppressing the basic assist force signal in accordance with the operation speed of the electric actuator, so that damping (braking) acts on the steering and an appropriate steering feeling can be obtained. .

  By adjusting the output signals of the return control means and the convergence control means according to the boat speed as in the tenth invention, the steering feeling can be optimized according to the boat speed of the small boat.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a power steering device for a small boat to which the present invention is applied, which shows an outboard motor as a steering means. In the following, a power steering for small boats having an outboard motor as a steering means will be described. However, a power steering for a small boat equipped with a propulsion device mounted on a hull and equipped with a rudder used for steering only (without a built-in propulsion device) Can be applied as it is by replacing the outboard motor with a rudder.

  A hull equipped with a gear device 4 and a power assist device 5 installed in the driver's seat of the hull 1 for converting a steering operation of a steering handle 2 into a push-pull operation of a push-pull cable 3 and an outboard motor 6 as steering means 1 and a link mechanism 7 for turning and steering the outboard motor 6 in accordance with the push-pull operation of the push-pull cable 3.

  As shown in FIG. 2, the outboard motor 6 includes a bevel gear (not shown) built in a gear housing 12 through a drive shaft (not shown) built in a drive shaft housing 11 for rotating an engine (not shown) built in an engine housing 10. An outboard motor main body 6A configured to transmit to the propeller 13 through the propeller 13 generates the propulsion force of the small boat by the rotation of the propeller 13. The outboard motor main body 6A is supported by a vertical shaft 14A (pilot shaft) provided on the swivel bracket 14 so as to be rotatable in a horizontal plane. The swivel bracket 14 is supported by a clamp bracket 15 fixed to the hull 1 by gripping the transom of the hull 1 via a horizontal axis 15A (clamp bracket shaft), and the swivel bracket 14 and the outboard motor main body 6A are viewed from the side of the boat. It can be flipped counterclockwise in the figure.

  As shown in FIG. 3, the link mechanism 7 transmits the push-pull operation of the push-pull cable 3 to the steering bracket 16 fixed to the outboard motor main body 6A and extending toward the hull 1 via the drag link 17. As a result, the outboard motor 6 is steered and rotated. For this reason, the end fitting 3B of the outer cable 3A of the push-pull cable 3 is fixed to the clamp bracket 15, and the rod 3C of the inner cable of the push-pull cable 3 protruding from the end fitting 3B of the outer cable 3A is drag-linked. 17. In the illustrated example, the end fitting 3B of the outer cable 3A penetrates both the clamp bracket 15 and the swivel bracket 14 and is fixed to the clamp bracket 15 by a nut, so that the clamp bracket shaft 15A is also used. Therefore, by the push-pull movement of the inner cable of the push-pull cable 3, the outboard motor main body 6A is rotated and steered in the horizontal plane via the vertical axis 14A via the drag link 17 and the steering bracket 16. The drag link 17 and the steering bracket 16 constitute the link mechanism 7.

  The gear device 4 is formed by a rack and pinion, as shown in FIGS. The rack gear 20 pushes and pulls the inner wire of the push-pull cable 3 by its movement. The pinion gear 21 is provided integrally with the output shaft 22. The output shaft 22 is connected to a steering shaft 23 connected to the steering handle 2 via a torsion bar 24, and receives a driving force from an electric motor 27 as an electric actuator via a worm gear 25 and a worm wheel 26. ing. That is, the output shaft 22 is rotatably supported by the gear case 19 by the distal end bearing 22A and the large-diameter bearing 22B which are both ends of the pinion gear 21, and the worm wheel 26 is integrally fixed adjacent to the large-diameter bearing 22B. On the rear end (steering handle 2) side, a tip of a steering shaft 23 is rotatably supported, and a tip of a torsion bar 24 is fixed by serration or the like. At the rear end of the output shaft 22, a torque pin 28 is disposed so as to protrude outward. The gear case 19 is fixed to a dashboard DB of a driver's seat by mounting screws or the like.

  The steering shaft 23 is rotatably supported by the gear case 19 also by a bearing 29, a rear end portion is connected to the steering handle 2, and a hollow torsion bar 24 having a rear end fixed by a pin is provided in the hollow interior. . On the outer periphery of the steering shaft 23, a torque ring 30 that is engaged by helical spline or involute helical serration is mounted.

  As shown in FIG. 9, the torque ring 30 includes a circumferential groove 31 provided on the outer periphery, and a groove 32 for engaging with the torque pin 28 of the output shaft 22 parallel to the axial direction. Is provided with a helical spline or an involute helical serration which engages with the outer periphery of the steering shaft 23, and a detection pin 36 of a position detection device functioning as a torque sensor 35 is fitted in the circumferential groove 31. Therefore, the torque ring 30 is axially movable and integrally rotates with the output shaft 22 by the engagement between the torque pin 28 and the groove 32.

  Further, when transmitting the steering torque by operating the steering handle 2 from the steering shaft 23 to the output shaft 22 via the torsion bar 24, the torque ring 30 engages with the outer periphery of the steering shaft 23 by helical spline or helical serration. , The shaft moves in the axial direction in accordance with the amount of vibration generated in the torsion bar 24, that is, the amount of relative rotation between the output shaft 22 and the steering shaft 23, and the axial movement is caused by the detection pin 36 engaged with the circumferential groove 31. Is moved in the axial direction, and the torque sensor 35 senses the steering torque.

  The torque ring 30 is movable in the axial direction with respect to the output shaft 22 by a torque pin 28 and an axial groove 32 and is connected to rotate integrally with the output shaft 22, and is inclined with respect to the steering shaft 23. Although it is described that the connection is made by a helical spline or helical serration, not shown, the connection is made by a helical spline or helical serration that is oblique to the output shaft 22 and is movable in the axial direction with respect to the steering shaft 23. Even if they are connected so as to rotate integrally with each other in the rotation direction, they can be operated in the same manner as described above.

  The worm wheel 26 is engaged with the worm gear 25. As shown in FIG. 10, the worm gear 25 is rotatably supported by the gear case 19, and one end of the worm gear 25 is coupled to the clutch plate 33 so as to be axially movable and integrally rotate. The clutch plate 33 can be brought into contact with and disengaged from a drive plate 34 that is driven to rotate by the assist motor 27. When the clutch coil (not shown) is excited, the clutch plate 33 and the drive plate 34 come into contact with each other, so that the driving force of the assist motor 27 can be transmitted to the worm gear 25. When the excitation of the clutch coil is released, the two plates 33, 34 are released. Are separated from each other, and the worm gear 25 and the worm wheel 26 are separated from the assist motor 27 and rotated from the output shaft 22 side. The assist motor 27, the worm gear 25, and the worm wheel 26 constitute the power assist device 5.

  FIG. 11 is a block diagram showing a controller (ECU) of the electric motor. Hereinafter, the processing executed by the ECU will be described in detail. The processing executed in the ECU mainly includes a basic assist current determining processing 50, auxiliary assist current determining processings 51 and 52, auxiliary assist current adding processings 53 and 54, and a feedback processing 55.

  The basic assist current determination process 50 is a process of determining a first basic assist current value according to the value of the output signal of the torque sensor 35, that is, the magnitude of the steering torque of the driver. This basic assist current determination processing 50 is to determine an assist current value corresponding to the magnitude of the steering torque (output signal value of the torque sensor 35) from data stored in advance in an EEPROM, a CPU flash memory, or a data area of a program. Is a process of determining data regarding the first basic assist current value. As shown in FIG. 12, the first basic assist current value has a slight dead zone with respect to the output signal of the torque sensor 35, and is thereafter substantially proportional to the square of the value of the output signal.

  FIG. 12 shows three characteristics in which the magnitudes of the steering torque and the assist current are changed. These characteristics are not limited to the three characteristics, but can be switched if there are at least two characteristics, or one characteristic if not switched. The characteristic in which the magnitude of the assist current is changed can be selected by a changeover switch 49 (a rotary switch, a toggle switch, or the like) provided near the steering handle 2. Further, this characteristic can be set according to the steering operator's preference according to the magnitude of the steering diameter of the boat, the magnitude of the engine output, the boat speed, and the like.

  The assist assist current determining process 51 is a process of differentiating the output signal of the torque sensor 35 to correct the cogging torque peculiar to the electric motor 27. The assist assist current adding process 53 is differentiating by the assist assist current determining process 51. This is a process of adding the calculated value of the output signal of the torque sensor 35 to the basic assist current value. In the assist assist current determination processing 51, the output signal of the torque sensor 35 is digitally differentiated 51A, for example, and the output signal of the torque sensor 35 is multiplied by the differential gain of the gain table that suppresses the oscillation of the corrected output value by making the output signal variable according to the steering torque value. Then, the excessive correction is output with a limit 51C. The second basic assist current value after the output signals of the auxiliary assist current determination processing 51 are added together becomes the basic command current value to the electric motor 27.

  The assist assist current determining process 52 is a process of differentiating the output signal of the torque sensor 35 to correct the phase delay of the electric motor 27. The assist assist current adding process 54 is differentiated by the assist assist current determining process 52. This is a process of adding the value of the output signal of the torque sensor 35 to the assist command current value of the final stage. In the assist assist current determination processing 52, the output signal of the torque sensor 35 is analog-differentiated 52A by, for example, an analog differentiator having high responsiveness and high resolution, and the output signal of the torque sensor 35 is made variable by the value of the steering torque. The differential gain of the gain table to be suppressed is multiplied by 52B, and output after multiplying by a limit 52C for phase delay correction and change amount correction. The assist current value obtained by adding the output signals of the assist assist current determination processing 52 becomes the final command current value to the driver PWM that drives the electric motor 27, and drives the electric motor 27 via PWM.

  The reason why the differential value of the output signal of the torque sensor 35 is added to the first basic assist current value and the reason why it is added to the final stage assist current value are as follows.

  First, as a first reason, the time from when the torque sensor 35 detects the steering torque to when the assist force is transmitted to the worm wheel 26 via the worm gear 25 (hereinafter, referred to as “delay time”). The point is to shorten it. That is, the purpose is to improve the response of the assist. Therefore, even when the steering torque detected by the torque sensor 35 changes abruptly (changes abruptly), the steering force can be assisted with the assist force corresponding to the suddenly changed steering torque.

  The second reason is that the purpose is to prevent the assist current value from oscillating. By differentiating, it is possible to prevent the oscillation by advancing the phase by 90 degrees.

  The feedback process 55 is a process for making the value of the current flowing through the electric motor 27 coincide with the assist current command value. When the electric motor 27 rotates, the electric motor 27 generates power in the same manner as the generator, and generates a back electromotive voltage, thereby reducing the value of the current flowing through the electric motor 27. For this reason, the steering force is assisted with an assist force smaller than the assist force corresponding to the steering torque, and the feeling is deteriorated. In order to prevent this phenomenon, the motor current value is made to match the assist current command value by feeding back and subtracting the current value flowing through the electric motor 27 from the assist current command value.

  FIG. 13 is a block diagram showing an ECU that changes the characteristic of the first basic assist current value according to the speed of the small boat (hereinafter, referred to as boat speed). The basic assist current determination process 50 shown in FIG. 13 also determines the first basic assist current value according to the value of the output signal of the torque sensor 35, that is, the magnitude of the steering torque of the driver. A moving averaged boat speed signal is input from the speed sensor 56, and as shown in FIG. 14, the assist current is small in a range where the boat speed is low, and the assist current increases as the boat speed increases. The assist characteristic is such that a large assist current to the electric motor 27 with respect to the steering torque flows according to the boat speed, and the steering can be performed with the same steering torque regardless of the boat speed.

  In addition, even in a boat with an outboard motor with one screw or a small boat equipped with a propulsion device on the hull itself, if there is only one screw, the direction of travel tends to be biased to the left or right due to the rotation of the screw. Yes, this trend is increased by increasing ship speed. In such a case, it is necessary to provide characteristics such that the assist force on one side, which is biased in accordance with the ship speed, is reduced and the assist force on the other side is increased. In addition, since the steering torque is also affected by the engine speed, the trim angle of the outboard motor, and the size of the boat, these state quantities are taken from sensors or switches, etc. The assist amount may be automatically set and selected.

  The boat speed signal is also input to the assist assist current determination processing 51, and is multiplied 51D by a differential gain that suppresses the generation of a correction output value by making it variable according to the magnitude of the boat speed signal. The correction output value of the current determination processing 51 is also corrected based on the boat speed.

  Further, the boat speed signal is also used for a return control process 57 and a convergence control process 58. That is, the return control processing 57 is a state in which the steering wheel 2 is difficult to return due to friction and inertia of the electric motor 27 when switching back to the right steering to return to the straight traveling state from the left steering (and vice versa). Is to improve. For this purpose, an assist current is applied in the rotation direction of the electric motor 27 (the direction of the self-aligning torque) when the steering handle 2 is returned, so that the return is assisted.

  Specifically, the voltage between the terminals of the electric motor 27 (the rotation direction of the electric motor 27) and the steering torque (the rotation direction of the steering handle 2) are compared to determine whether the steering handle 2 is in the cut state or the return state 57A. In the case of the return state, the return command current value previously set in the table 57B according to the boat speed signal is passed through the low-pass filter 57C and the limiter 57D so that the output value does not suddenly change or become excessive. The return command current value is added to or subtracted from the first basic assist current value according to the rotation direction of the electric motor 27 to assist the steering handle 2 in the return direction. It is desirable that the return control process 57 be provided with a dead zone in order to prevent chattering at the transition point between the return of the steering wheel and the cut.

  The convergence control processing 58 is based on the assumption that, with one outboard motor as the steering means, the steering force is in the same direction as the rotation direction of the propeller 13 as viewed from the stern as the propeller speed increases, for example, in the case of right rotation, the steering force When the steering wheel 2 is not held, the steering may be steered. When the return speed of the steering handle 2 is increased, the steering is returned too much by the inertia of the electric motor 27 and the steering handle 2 (overshoot). In this case, damping is controlled in response to the possibility of damping.

  Specifically, the convergence gain set in advance in the table 58A according to the boat speed signal is multiplied by the rotation speed of the electric motor 27 to obtain a convergence current value, and a low-pass current value is set so that the current value does not suddenly change or become excessive. The first basic assist current value is subtracted by the convergence current value via the filter 58B and the limiter 58C to suppress the rotational speed of the electric motor 27 from excessively increasing.

  In the power steering apparatus for a small boat having the above-described configuration, when the steering handle 2 is steered to the right (left) from the neutral state, for example, the steering shaft 23 and the torque ring 30 rotate right (left) and torsion. The output shaft 22 is rotated right (left) via the bar 24, and the inner cable of the push-pull cable 3 is pushed out from the end fitting 3B (pulled back into the end fitting) via the rack and pinion 20, 21. Then, the steering bracket 16 and the outboard motor 6 are rotated counterclockwise (clockwise) in the horizontal plane via the drag link 17. When the outboard motor 6 rotates counterclockwise (clockwise), a clockwise (counterclockwise) moment acts on the hull 1, and the hull 1 moves forward while turning rightward (leftward).

  In the above steering, the torsion bar 24 is damaged according to the steering force, and the damage changes the axial position of the torque ring 30 according to the torsion direction of the torsion bar 24, and this change causes the detection pin 36 to move. The torque is detected by the torque sensor 35 as a steering torque. The detected steering torque is input to the ECU, the basic assist current is determined, and the assist assist current determination processes 51 and 52 and the assist assist current addition processes 53 and 54 are executed as described above. 27 is driven and feedback processing 55 is performed to assist the steering operation of the steering wheel 2.

  FIG. 15 shows another embodiment of the push-pull cable 3 of the power steering device for small boats. In the first embodiment, the link mechanism 7 is operated using one push-pull cable 3. Instead, the link mechanism 7 is operated by using two push-pull cables 3. Although both ends 3C of the inner cable of the two push-pull cables 3 are connected to the drag link 17, the end fitting 3B of the first push-pull cable 3 also serves as the clamp bracket shaft 15A. The remaining end fitting 3B of the push-pull cable 3 is fixed to the clamp bracket 15, but is not used as the shaft 15A. As described above, by using the two push-pull cable holes 3, the operating force to be transmitted can be increased.

  16 and 17 show still another embodiment of the power steering device for small boats. In the first embodiment, a circular gear device 4A is used instead of using a rack and pinion as the gear device 4. It is intended to be used. That is, in FIG. 16, a drum-shaped gear 42 that meshes with the pinion 21 of the output shaft 22 is used. The drum-shaped gear 42 is provided with a groove 43 around which a wire is wound. The drag link 17 of the link mechanism 7 is pushed and pulled. In FIG. 17, a drum-shaped internal gear 44 that meshes with the pinion 21 of the output shaft 22 is used, and a groove 46 around which a wire is wound is provided on the outer periphery of the drum 45, and a wire wound around the groove 46 is provided. The drag link 17 of the link mechanism 7 is pushed and pulled. In this case, the inscribed gear 44 is not provided on the entire circumference of the drum 45 but is provided in a part in a fan shape.

BRIEF DESCRIPTION OF THE DRAWINGS The perspective view of the power steering device for small boats which shows one Embodiment of this invention. FIG. 2 is a side view showing the outboard motor as a steering unit. FIG. FIG. 2 is a plan view of a gear device and a power assist device of the power steering device. FIG. 2 is a side view of a gear device and a power assist device of the power steering device. FIG. 2 is a side view of the gear device and the power assist device of the power steering device as viewed from a handle side. FIG. 2 is a side view of a gear device of the power steering device and a gear device of the power assist device. FIG. 2 is a cross-sectional view of a gear device and a power assist device of the power steering device. FIG. 2 is an enlarged view of a torque ring of the power steering device. FIG. 2 is a cross-sectional view of a power assist device of the power steering device. FIG. 2 is a block diagram showing a control system of the electric motor. FIG. 4 is a characteristic diagram showing an assist characteristic based on a basic assist current value. FIG. 4 is another block diagram showing a control system of the electric motor. FIG. 14 is a characteristic diagram showing an assist characteristic based on a basic assist current value in FIG. 13. The perspective view showing another example of push-pull cable 3 of the power steering device for small boats. Sectional drawing which shows another Example of the power steering device for small boats. Sectional drawing which shows another Example of the power steering device for small boats.

Explanation of reference numerals

Reference Signs List 1 hull 2 steering handle 3 push-pull cable (connection means)
4, 4A gear device 5 power assist device 6 outboard motor as steering means 7 link mechanism 20 rack 21 pinion 22 output shaft 23 steering shaft 24 torsion bar 25 worm gear 26 worm wheel 27 electric motor (electric actuator)
30 Torque ring 35 Torque sensor

Claims (10)

Steering means arranged rotatably in the horizontal direction at the rear of the hull;
A link mechanism for turning and steering the steering means at the rear of the hull;
A gear device that is steered by a steering wheel of a driver seat;
Connecting means for transmitting the output of the gear device to a link mechanism;
A torque sensor that detects a steering torque input to the gear device from the steering handle;
An electric actuator that assists the gear device in a steering operation direction according to at least a detection signal of a torque sensor;
A power steering device for a small boat, comprising: a controller that receives and calculates a detection signal of the torque sensor to drive an electric actuator.   The power steering device for a small boat according to claim 1, wherein the gear device, the torque sensor, and the electric actuator are integrally combined and assembled.   The power steering device for a small boat according to claim 1 or 2, wherein the electric actuator is connected to a gear device via a clutch device.   The power steering device for a small boat according to any one of claims 1 to 3, wherein the connecting means comprises two push-pull cables having the same configuration.   A controller configured to calculate a basic assist force signal of the electric actuator according to a detection signal of the torque sensor; and a servo amplifier process that outputs a final assist force signal of the electric actuator according to the basic assist signal. And assist assist force determining means for differentiating the detection signal of the torque sensor, outputting a differential term thereof, and outputting a correction signal for suppressing fluctuations in the assist force of the electric actuator. The power steering device for a small boat according to any one of claims 1 to 4.   The basic assist force determining means includes a plurality of output characteristics of the basic assist force signal and selects one of the output characteristics or an output characteristic changing means for changing the output characteristic of the basic assist force signal. The power steering device for a small boat according to claim 5, wherein an output characteristic of the basic assist force signal is changed according to a propulsion state such as a speed.   The said assist assist force determination means adds a correction signal to a basic assist force signal and / or a final assist force signal, and suppresses the fluctuation | variation of the assist force of an electric actuator, The Claims 5 or 6 characterized by the above-mentioned. Power steering equipment for small boats.   The controller according to claim 1, further comprising: a return control unit configured to determine a turning-back state of the steering handle from an output signal of the torque sensor and a rotation direction of the electric actuator, and to increase a basic assist force signal in the turning-back direction. The power steering device for a small boat according to any one of claims 5 to 7.   The power steering device for a small boat according to any one of claims 5 to 8, wherein the controller includes convergence control means for suppressing a basic assist force signal according to an operation speed of an electric actuator. .   10. The power steering apparatus for a small boat according to claim 8, wherein output signals of the return control means and the convergence control means are adjusted according to a boat speed.

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