JPS5911965A - Electric power steering device - Google Patents

Abstract

PURPOSE:To permit a steering operation to be conducted even if all of an electric motor control circuit, a clutch control circuit and a power source control circuit is defected, by connecting the above three circuits to a power source in parallel. CONSTITUTION:An electric motor control circuit 70, a clutch control circuit 79 and a power source control circuit 80 are connected to a power source 71 in parallel. The clutch control circuit 79 receives a signal from an electric motor input detecting device 78. The power source control circuit 80 receives a signal from a clutch input detecting device 82, and stores operational conditions of an electric motor and an electric clutch. If any signals defferent from the signal stored by the control circuit 80, the control circuit 80 acts to stop the operations of the electric motor and the electric clutch by turning off a power switch or a manual power switch 72. The electric motor control circuit 70 independently controls the electric motor in response to an input from an input torque irrespective of the other two circuits, thus permitting an electric or a manual steering operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small pneumatic power steering system for a vehicle that uses a power source and an electric motor at 17 to reduce the steering force of the vehicle's steering wheel.

Compared to hydraulic power steering devices, electric power steering devices do not require an oil pump as a power source that is constantly connected directly to the engine, so there is no loss of engine horsepower. Since no hydraulic fluid is used, there is no need to worry about hydraulic fluid leakage or dirt, and maintenance is easy. Easy to assemble as there is no need for hydraulic piping and only electrical wiring is required. Since there is no need for highly precise and delicate equipment such as hydraulic control valves, a low-cost system can be expected.

The number of parts and weight are reduced, and the engine area is streamlined, making maintenance easier. Although it has many advantages in terms of sharing main parts with the manual steering device, and many proposals have been made, the reasons why it has not been put into practical use are as follows: 1. Electric motors with sufficient output to be generally used as a drive source (d, steering system parts and 17) are quite large in size, and are difficult to install due to lack of space in passenger cars. Vinegar. 2. Since one lightning source for a passenger car is 12V DC, the electric motor uses 12V DC.
It is common to use a 2V DC small electric motor,
The torque generated by these motors is small, several t-(1), and is greatly influenced by bearing resistance, slider resistance, etc.
The efficiency of the electric motor alone is 50 to 65 mm. If you carelessly increase the bearing diameter or slider diameter, or use a worm gear with high loss in the first stage reducer, the efficiency including the steering gear will drop to 30% or less, which will lead to smaller electric motors, This hinders weight reduction17, requires a large current, and makes installation in passenger cars difficult. 3. In an electric power steering system, an electric motor and a reduction gear with a large reduction ratio are connected to the human power shaft side of the steering gear, so friction on the input shaft side inevitably increases compared to when the steering gear is used alone. do. This inhibits the return of the steering wheel in a passenger car, makes the torque difference between the steering force and the steering force a dog, and gives a non-direct steering feeling in the micro-steering area during fast-moving high-speed driving. However, it is inferior in comparison to the final hydraulic type, and is preventing its practical use. The electrical control circuit of the 4 electric power steering system has no track record of reliability, and there are problems with important safety components and safety considerations in 17. etc.

SUMMARY OF THE INVENTION In order to solve these problems, it is an object of the present invention to provide an electric power steering system having a particularly safe and reliable electric control circuit.

Below, drawings showing embodiments of the present invention will be described.

A steering gear assembly 1 mounted on a vehicle body is connected to an output shaft 1 via an intermediate 11117 having cross joints 5 at both ends. A steering column assembly 8 attached to the vehicle body with a bracket 6 rotatably supports an input shaft 1o and an output ill, to which a steering wheel 9 is attached at the upper end. The steering link column assembly 8 has a transmission device 2
The transmission device #2 receives the rotation of the electric motor 3 through a torque cable 4. The transmission device 2 includes a housing 30 on the human power shaft side and a cover 31 on the output shaft side, which rotatably support the human power shaft 1o and the output shaft tx with two ball bearings 26, 27 and one ball bearing 29. The housing 3 ( ) and the cover 31 are aligned and fitted with a spigot, and are connected by bolts (not shown). Human power axis 1
0 and output shaft 11 are torsion bar 12 and two pins 13
By twisting the torsion bar 12, they can be rotated relative to each other, and both are supported by needle roller bearings fitted in the large diameter part of the torsion bar 12, so that the torsion bar 12 can rotate smoothly. Target rotation is guaranteed. This relative rotation of the input and output shafts is limited by a stopper portion 14 provided at the abutting portion of both shafts so that excessive l·lux is not applied to the torsion bar 12. FIG. 3 shows the structure of the stopper part 14. In other words, the input shaft] −
017), two □ protrusions 32 are provided at the end, n2, output I+III] are fitted into the two notches 33 provided at the end of 1 with a predetermined gap, and the relative rotation corresponding to the gap After this is allowed, the protrusion 32 and the notch 33 are brought into engagement. The input/output shaft 10, Jl has flange parts 15, 16 facing each other, and the flange part 15 of the human power shaft has two
A pin 17 is press-fitted into the pin 17, and a planetary gear 1 is attached to the pin 17.
9 is rotatably fitted, and two pins 18 are similarly press-fitted to the 7 flange portion 16 of the output shaft, protruding from both sides of the flange portion 16, and a planet is attached to the portion of the pin 18 protruding toward the input shaft 10 side. The gears 20 are rotatably fitted, and both planetary gears 19, 20 mesh with a common sun gear 21. The sun gear 21Vi is rotatably supported by the output shaft 11 at a shaft portion between the input shaft 10 and the flange portion of the output N11l. The planetary gear J9 of the input shaft 10 meshes with a link gear 22 rotatably fitted to the housing 30, and the planetary gear 20 of the output shaft meshes with a ring gear 23 fitted non-rotatably to the housing 30. ing. There is a notch 34 on the outer peripheral surface of the ring gear 22 on the input shaft side.
is provided, into which the spherical head of the pin 24 fits. The other end of the pin row is fitted and fixed into a hole 37 provided in the center of the spool 25, and the spool 25 is slidably fitted into a hole 39 provided in the housing 30 in a direction perpendicular to the human power shaft 10. , 7. As shown in FIG. 4, the hole 39 is closed at both ends with a lid 83, and a spring 35 is interposed between the $83 and the spool 25. hold in neutral position. A spool 25 of a potentiometer, a differential transformer, a pulse encoder, etc. is attached to one lid 83.
A handle torque detection device 36 is fixed to detect the position of the handle torque detection device 36 and convert it into an electric signal. Go inside and out. In addition,
Reference numeral 38 in FIG. 4 is a hole provided in the housing 30 to allow movement of the pin 24.

A planetary gear 41 is rotatably fitted into the protruding part of the pin 18 that is press-fitted into the flange 16 of the output shaft, and a ring gear 40 that meshes with this is fixed non-rotatably to the housing 30. and the sun gear 42 is the output shaft 1]
It is rotatably supported on the outer periphery of and meshes with the planetary gear 41. Further, a spline on the inner circumference of the key 1 rear 43 is engaged with the sun gear 42, and two pins 44 are press-fitted into the key 1 rear 43, and a planetary gear 45 is rotatably fitted into each of the pins 44. A sun gear 46 and a ring gear 47 mesh with the planetary gear 45. The sun gear 46 is rotatably supported on the outer periphery of the output shaft J1, and the ring gear 47 is rotatably fitted into the housing 30. A large number of recesses 52 having slopes as shown in FIG. 5 are provided on the outer periphery of the ring gear 47. A pin 54 driven by a lensoid 53 fixed to the outer surface of the housing 30 connects the housing 30 and the ring gear 47.
When the nnoid 53 is turned on and the pin 54 engages with the recess 52 as shown in the figure, the link gear 47 is pushed against the housing 3o and becomes unrotatable. , when the solenoid 53 is turned off, the pin 54
With the force of the spring 55, the ring gear 17 is pulled out from the recess 52 and the ring gear 47 can be rotated. When the thread/id 53 is turned off and the pin 54 is separated 17 from the recess 52, the end of the pin 54 on the side opposite to the ring gear turns off a contact 77 provided on the power line connecting the solenoid 53 and the power source. On the other hand, the sun gear 46 is rotatably supported on the output shaft 1 by a needle roller bearing 69, and meshes with the spline on the inner surface of the reduction gear 48, thereby rotating as a unit. Reduction gear 48μ It meshes with a small gear 49 provided on the reduction manual shaft 84, and the reduction gear 48 and 40 small gears other than the worm and worm wheel are highly efficient spur gears, helical gears, and umbrellas that can rotate in the forward and reverse directions. It can be anything such as gears. The deceleration human power shaft 84 is in the housing 30
and is rotatably supported on the cover 31 by two small-diameter ball bearings 50, and connected to the electric motor 3 by a torque cable 4 17,
The rotation of the electric motor is transmitted to the reduction gear 48 with little friction. Since friction increases when the torque cable 4 is bent to a large extent, the action of the transmission device on the cutting edge of the deceleration input shaft 84 will be explained using helical gears and bevel gears as necessary.

In order to give rotation to the human power shaft 10 when there is no load torque on the output shaft 11 side, the ring gear 23 on the output shaft side of the first two-plane planetary gear set is fixed, and the ring gear 22 on the human power shaft side is fixed.
Since the rotation is suppressed by the set load of the i-i spring 35, they do not rotate together, and the planetary gear 1 of the output shaft 11.2 station 1
9.20 and the sun gear 21 rotate, and the output shaft 11 rotates relative to the input shaft 10 without causing any rotation relative to the human power shaft 10.
rotates in the same direction and at the same speed. When there is a load torque on the output shaft 111111, when the torque applied to the input shaft 10 overcomes the load torque, the torsion bar 12 is twisted but the output shaft 11 rotates. When the rotational torque of the link gear 22 generated by the human torque 6τ of the human power shaft 10 exceeds the torque that suppresses the rotation of the ring gear 22 due to the set load of the spring 35, the spring 35 and the torsion bar 12 are deflected, causing the ring gear 22 to rotate. , spool 25
produces a displacement with respect to the neutral position. Human torque is the output shaft]
If the load torque of 1 is balanced, the output shaft 11 rotates (7, common sun gear 2) for input torque greater than that, so the spring balance, torsion bar 12 and spool 25 maintain their displacement. Therefore, the human-powered output shaft 11 rotates in the same direction and at the same speed. Therefore, the magnitude and direction of the human-powered torque is converted into the displacement of the spool 25 due to the displacement of the spring 35 and torsion bar = 12 (7 , converts the spool position into an electric signal to form a handle torque detection device.The rotation of the electric motor is transmitted to the deceleration input shaft material by the torque cable 4, and is transmitted to the small gear 49, the deceleration gear 48, and the sun gear 46. The transmission is transmitted to the planetary gear 45 that meshes with the planetary gear 45 and the link gear 47 that meshes with the planetary gear 45. However, when the ring gear 47 is fixed by the solenoid 53, the planetary gear 45 rotates and revolves along the inner circumference of the ring gear 47, and the carrier 4: Rotate 3.Carrier 4
:3 rotation is transmitted to the sun gear 42, and the rotation of the sun gear 42 is transmitted to the planet gear 41, but the rotation of the sun gear 42 is transmitted to the ring gear 40.
)・Using: (Since it is fixed at 0, the planetary gear 41 rotates and revolves along the inner circumference of the ring gear 40, transmits the rotation to the flange portion 16 of the output shaft, and outputs the output shaft 111.
Rotate. When the ring gear 47 is not fixed by the solenoid 53, the ring gear 47 is rotated by the planetary gear 45, so the revolution of the planetary gear 45, that is, the rotation of the carrier 43 does not occur, and the rotation of the electric motor is not transmitted to the output shaft 11. do not have. That is, the ring gear 47, solenoid 53, etc. function as an electric clutch.

Next, the configuration of the electrical control system shown in FIG. 6 will be explained.The electric signal indicating the direction and magnitude of the noddle torque is transmitted from the above-mentioned handle torque detection device 36 to the power supply control circuit 80 and the clutch control circuit 79. and motor control circuit 70
is input. In addition, an information human power device 8 such as a detector detects the position of the shift lever for operating the transmission that changes the vehicle speed center or the transmitted engine rotational speed and converts it into a drowsiness signal.
The signal No. 1 is sent to the power supply control circuit 80 and the motor control circuit 70.
is man-powered. A signal from a clutch human force detection device 82 that detects human force applied to the solenoid 53 of the electric clutch enters the power supply control circuit 80. Furthermore, a signal from a motor human power detection device 78 that detects human power to the electric motor 74 including a drive circuit is transmitted to a power supply control circuit 80 and a clutch control circuit 79.
to use human power. An automatic power switch 73 is provided on the power line connecting the electric motor 74 including the motor input detection device 78 and the drive circuit and the power source 71, and a manual power switch 72 is provided on the power side of the automatic power switch 73. Disconnected clutch human power detection device 82 and electric clutch solenoid 5
3 to the automatic power switch 73, there are a contact 77 turned off by the solenoid pin 54, a solenoid, and a drive switch 76, and a circuit that distributes power to the timer switch 75 in parallel with the contact 77 from between the two. is provided. timer switch 75d, timer switch 75
and the solenoid drive switch 76 are turned on at the same time, the solenoid 53 works, and the pin 54 moves into the recess 52 of the ring gear 47.
It protrudes inward of the housing 30 to engage with the housing 30, and remains in the ON state only during the time when the pressed contact 77 is in the ON state, and normally remains in the OFF state. It has a function such that it does not enter the on state unless the command 1j is set once. The power control circuit 80, the clutch control circuit 79, and the motor control circuit 70 are connected in parallel to a power line branched from between the automatic power switch 73 and the manual power switch 72. The power supply control circuit 80 stores the conditions under which the electric motor and the electric clutch are put into operation, and always keeps the automatic power supply switch 3 in the ON state. The human input signals from the device 78 and clutch human power detection device 82 are compared and monitored with the memorized conditions, and if a signal that does not match the memorized conditions is received, the automatic power switch 73 is set to Switch to the extraction device. For example, the stored operating conditions corresponding to the signal from the information manpower device 81, such as the vehicle's weight being 30 km or less, the position of the shift lever being in the first forward gear, the second gear, and reverse, and the steering wheel torque ν.・The electric motor human power detection device still detects the electric motor force detection device even under operating conditions other than the stored operating condition corresponding to the signal from the steering torque detection device 36 of 60 km or more and the steering wheel torque being zero in the fourth forward gear. If the signal from 78 or clutch human power detection device 82 continues to be input, the automatic power switch 7
3 is turned off.

In the clutch control circuit 70, the electric motor 74 is connected to the electric motor control circuit 7.
0 memorizes the conditions for entering the operating state [count 7] Always leave the solenoid 53 of the electric clutch in the OFF state and compare the signal from the motor input detection device 82 and the signal from the handle torque detection device 36. 7. Only when the stored conditions match (7), a signal is sent to the timer switch 75 and the solenoid drive switch 76 to activate the solenoid 53 of the electric clutch and connect the electric clutch. This causes the electric motor to rotate. When the electric motor is rotating, the rotation of the electric motor is transmitted to the output 1lI111.If the electric motor rotates despite the conditions in which it should rotate, the electric clutch is not connected and the electric motor The rotation of the motor is not transmitted to the output shaft 1].The motor control circuit 70 stores the conditions under which the motor enters the operating state, and if the signals from the steering wheel torque detection device 36 and the information manpower device 81 match the conditions, The electric motor 74 is actuated.The information input device 81 can be used to input information such as vehicle speed or shift lever other than the steering wheel torque. The steering can be switched from electric to manual depending on the position of the steering wheel, allowing for a wide selection of areas of use.-!
In addition, when the information input device 81 is a vehicle speed sensor, the gain of the motor control circuit 70 is changed (7, the motor is driven at j ~ corresponding to the vehicle speed (7, -1 is heavy for high vehicle speeds, and low vehicle speeds are The structure of the transmission device 2 is the same as that shown in FIG. 2, and the structure of the transmission device 2 is the same as that shown in FIG. is provided on the output shaft 11, and the pinion shaft serves as a manpower 10 at the top and an output shaft 11 at the bottom.The pinion shaft is attached to a three-piece gearbox of the electric motor, and is connected to the transmission device 2 by a torque cable 4. However, the operation and effect are the same as in the first embodiment.

In the electric power steering device of the present invention, a motor control circuit, a clutch control circuit, and a power supply control circuit are jointly connected to a power supply 7, and a signal from a motor input detection device is input to the clutch control circuit, and a power supply control circuit is connected to the power supply. The control circuit receives signals from the motor input detection device and the clutch human power detection device, so the power supply control circuit stores the operating conditions of the motor and electric clutch, and if a signal different from the memory is input, turn the power switch off. or issue an alarm to force the driver to turn off the manual power switch, thereby preventing the operation of the electric motor and electric clutch.
stop. The clutch control circuit memorizes the operating conditions of the electric motor 7, and if a signal different from the memorized signal is manually applied, the electric clutch is not connected and the rotation of the electric motor is not transmitted to the mechanical steering system. In addition, no matter what state the other two circuits are in, the electric motor control circuit independently controls the electric motor according to the human power from the human torque, so even in such cases, it is not possible to steer the electric motor manually. is possible. In this way, even if individual control circuits fail, even one control circuit remains intact.
L, at least manual steering is possible, fatal danger can be avoided, and there is an effect that it is possible to provide an electric steering device with sufficient safety. In addition, in an embodiment equipped with an information manpower device, the signal is sent to the power supply control circuit, and the power supply control circuit operates the power switch according to the position of the nofton bar that changes the vehicle speed. 2 Manual steering gear and 7 automatic selection of use areas, which have great effects. Among them, when the information human power device is used as a vehicle speed sensor, in addition to the effect described in F, the gain of the motor control circuit can be changed by the signal sent to the motor control circuit. In the following embodiments, it is possible to arbitrarily select the range of use as a power steering device and a manual steering device. Furthermore, in an embodiment in which the electric clutch is connected to the mechanical steering system 1 (a ring gear of a planetary gear reduction device provided therein, a pin driven by a solenoid is engaged and disengaged from the four parts having an inclined surface provided on the outer circumferential surface of the ring gear). The control circuit may fail and the electric clutch is connected, the power supply control circuit may fail and the automatic power switch is turned on, or the alarm device may not work and the manual main valve switch may be turned off. Even in the worst case scenario, in which the electric motor continues to rotate in one direction due to a failure, or locks up and becomes unable to rotate, if the ring gear attempts to rotate due to excessive torque, the slopes of the four parts will act as a force l, causing the pin to Overcoming the electromagnetic force of the solenoid, press 7 and return 7, turn off the contact on the power line, disengage the electric clutch, and set the mechanical steering system to manual, so even if all three control circuits fail, steering will not be possible. This is a problem.Even in a malfunction state such as when the electric motor is free to rotate when the power is turned off, the electric clutch is off, and the electric clutch is turned on, the steering will not become impossible.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a conceptual side view of an electric power steering device, FIG. 2 is an enlarged longitudinal cross-sectional view of a transmission device, and FIG. Figure 4 is an enlarged cross-sectional view taken along line IV-IV in Figure 2, Figure 5 is an enlarged cross-sectional view taken along line ■-v in Figure 2, and Figure 6 is an enlarged cross-sectional view taken along line IV-IV in Figure 2. 7 is a conceptual side view of the main parts of the electric power steering device showing another embodiment in which the transmission device is installed. Explanation of symbols 1 Steering gear Assembly 2: Transmission device 3: Electric motor 4: Torque cable 8 Steering column assembly
9: Steering wheel 1o: Human power shaft 11: Output shaft ]] 2: Tone Yonbar 17.2°, 41.45: Planetary gear 21.42.46: Sun gear 22.23.4
0.47: Ring gear 24: Pin 25 Nisbourg
26.27.29.5o: Ball bearing; 3o: Housing-': n: Cover 34: Notch 35: Spring 36
: Handle torque detection device 43: Carrier 48: Reduction gear 49: Small gear 52: Recess 53: Solenoid
54: Pin 55: Spring 7o: Motor control circuit 71
: Power supply 72: Manual power switch 73: Automatic power switch 74: Electric motor including drive circuit 75: Timer switch 76: Solenoid drive switch 77: Contact 78
: Electric motor input detection device 79: Cranochi control circuit 80:
Power supply control circuit 8]: Information input device 82: Clutch input detection device 84: Deceleration input shaft patent applicant NSK Ltd. Figure 1 q Figure 2 11) Figure 6

Claims (1)

[Scope of Claims] 1. A mechanical steering system including a steering gear that transmits steering torque applied to a steering wheel to steering wheels;
A steering wheel torque detection device that detects the direction and magnitude of human-powered steering torque, an electric motor that supplies steering torque to a mechanical steering system, a motor input detection device that detects input to the electric motor, and a signal from the steering wheel torque detection device. An electric motor control circuit that controls the drive of the electric motor based on the motor, an electric clutch that transmits and interrupts the rotation of the electric motor to the mechanical steering system, a clutch human power detection device that detects input to the electric clutch, and a steering wheel torque detection device. and a clutch control circuit that drives the electric clutch based on the signal from the electric motor human force detection device, and an electric circuit from the power source that leads to the electric motor and the electric clutch based on the signals from the steering wheel torque detection device, the electric motor human force detection device, and the clutch human force detection device. An electric power steering device having a power control circuit for operating an automatic power switch provided therein, and having a motor control circuit, a clutch control circuit, and a power control circuit connected to a power source in parallel between the automatic power switch and the power source. 2. A mechanical steering system including a steering gear that transmits the steering torque applied to the steering wheel to the steering wheels, a steering wheel torque detection device that detects the direction and magnitude of the steering torque applied by human power, and a steering torque detection device that detects the direction and magnitude of the steering torque applied to the steering wheel. an electric motor that supplies the motor, a motor input detection device that detects human power to the electric motor, a motor control circuit that controls the drive of the electric motor based on the signal from the steering wheel torque detection device, and a motor control circuit that transmits and transmits the rotation of the electric motor to the mechanical steering system. An electric clutch that disconnects the
A clutch input detection device that detects input to the electric clutch, a clutch control circuit that drives the electric clutch based on signals from a handle torque detection device and a motor human power detection device, a steering wheel torque detection device, an electric motor human power detection device, and a clutch. It has a power supply control circuit that operates an alarm device installed in the electrical circuit from the power source leading to the electric motor and the electric clutch based on the signal from the input detection device, and a manual power switch installed between the alarm device and the power source. An electric power steering system in which a motor control circuit, a clutch control circuit, and a power supply control circuit are connected to a power supply in parallel between an alarm device and a manual power switch. 3. The electric power steering system according to claim 1 or 2, wherein the power supply control circuit and the motor control circuit are manually supplied with signals from an information input device. 4. The electric power steering system according to claim 3, wherein the information manpower device is a vehicle speed sensor. 5. The electric clutch has a structure in which a pin presses a contact point that makes a slope on the outer peripheral surface of a ring gear of a planetary gear set in a mechanical steering system into a cloth state. The electric power steering device according to item 1 and item 2.