JPS62218276A - Control method for motor driven power steering - Google Patents

Abstract

PURPOSE:To smoothly transfer the driving of a vehicle from its stopping condition to running condition, by controlling a clutch current and motor applied voltage on the basis of steering torque and a car speed, in the case of a power steering in which the turning effect of a motor is transmitted to a pinion shaft through an electromagnetic slip clutch. CONSTITUTION:The second rack toothed part 6b is separately provided from a rack toothed part, meshed with a pinion shaft controlled by a handle, of a rack shaft 6, and the second pinion shaft 18, turned by a DC motor 13 through an electromagnetic slip clutch 14, worm shaft 15, worm wheel shaft 16 and an electromagnetic clutch 17, is meshed with the second rack toothed part 6b. Each control element 13, 14, 17 is controlled by a control unit 9. Here the control unit 9 is constituted providing each determining means 9d, 9f, which respectively determines motor applied voltage and a clutch current by an applied voltage value and a clutch current value read from predetermined memory means 9c, 9e corresponding to a car speed and steering torque, and the control unit 9 controls the motor 13 and the slip clutch 14 on the basis of the determined value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motor-driven power steering control method for auxiliary biasing of a steering device of an automobile by the rotational force of a motor.

[Conventional technology]

Conventionally, there is a device of this type in which the driving force of a motor is transmitted through a speed reducer and auxiliary bias is applied to the steering shaft by a transmission mechanism such as a gear or a belt. [Problems to be solved by the invention] Conventional steering The device is constructed as described above, and in the conventional system, the auxiliary load energization is cut off when the vehicle moves from a stopped state to a running state and the vehicle speed exceeds a certain speed. There was a problem that the 9th row was not smooth and gave a strange feeling to the driver.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a motor-driven power steering control method that allows the transition from a stop to a running state to be performed clearly and without any discomfort. do.

[Means for solving problems]

The power steering control method according to the present invention controls the electromagnetic slip clutch current and the motor applied voltage.
This is done using values stored in advance corresponding to the steering torque and vehicle speed.

[For production]

Since the fuel steering control method of the present invention is carried out by the above-mentioned control method, it is possible to shift the vehicle from a stop to a running state only by the control program of the control unit without changing each component of the device. It can be done cleanly and without feeling.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a motor-transforming power steering device, in which 1 is a handle, 3 is a torque sensor 4a that outputs an electric signal in accordance with the rotational force applied by the handle 1-4 is the first universal joint,
4b is a second universal joint; 2a is a first steering shaft that connects the handle l and the torque sensor 3; 2b is a second steering shaft that connects the torque sensor 3 and the first universal joint 4a; :This is the third steering shaft that connects the universal steering shaft 4a of Ca1E1 and the second universal steering shaft 4b. 5 is a first pinion shaft connected to the second universal soybean shaft 4b; 6 is a rack shaft having a first rack tooth portion 6a and a second rack tooth portion 6b that mesh with the first pinion shaft 5; 7a is a gold joint connecting one tie rod 8a and one end of the rack shaft 6, and 7b is a sita pole joint connecting the other tie rod 8b and the other end of the rack shaft. 91)=ry)C
I-/l/unit, 10 is a vehicle speed sensor that detects the vehicle speed, 11 is an in-vehicle batch IJ-, 12 is a key switch, 13 is a DC motor with shunt winding or a magnet field, and the control unit is connected from the battery 11. 9. Reference numeral 14 denotes an electromagnetic clutch that is directly connected to and driven by the output shaft of the motor 13, and is, for example, a clutch clutch or a hysteresis clutch. 15 is a worm shaft connected to the output shaft of the slip clutch 14 to form a speed reducer; 16 is a worm wheel shaft that meshes with the worm shaft 15 and is driven; 17 is a second tooth of the worm wheel shaft 16 and the rack shaft 6; 6b and the second pinion shaft 18
This is an electromagnetic clutch that connects and disconnects the mechanical connection between the two according to instructions from the control unit 9.

FIG. 2 is a block diagram showing a specific configuration of the control unit 9, in which 9a is a steering torque measuring means for measuring steering torque based on input from the torque sensor 3, and 9b is a vehicle speed measuring means for measuring vehicle speed based on input from a vehicle speed sensor 10. 9C is a vehicle speed corresponding motor applied voltage storage means for storing and storing the voltage applied to the motor corresponding to the vehicle speed and steering torque; 9d is a vehicle speed corresponding motor applied voltage storage means corresponding to the vehicle speed and steering torque; 9e is an electromagnetic slip clutch 14 corresponding to the vehicle speed and steering torque.
heavy-speed clutch current storage means for memorizing and retaining current;
9f is a clutch current determining means that determines a clutch current based on a clutch current value read from a vehicle speed corresponding clutch current storage means 9e corresponding to the vehicle speed and steering torque, and 9g is a voltage applied to the motor 13 based on the output of the motor voltage determining means 9e. 9h is a clutch current control means 91 that controls the current of the electromagnetic slip clutch 14 based on the output of the clutch current determining means 9f;
is an electromagnetic clutch control means that controls on/off the V electromagnetic clutch 17 according to the vehicle speed.

Next, the operation will be explained with reference to FIGS. 3 to 7.

FIG. 3 is a clutch current vs. transmission torque characteristic diagram of the electromagnetic slip clutch 14, and FIG. 4 is a control characteristic diagram of steering torque vs. voltage applied to the motor 13 and slip latch 14 current.

Figure 7 shows the control program 7 of the control unit 9.
g-chart.

First, when the key switch 12 is turned on to start the engine, the electromagnetic clutch 17 is turned on and the worm wheel shaft 16 and the second pinion shaft 18 are connected. When a rotational force is applied to the handle l in this state, the control unit 9 controls the motor 13 and the electromagnetic clutch 14 as shown in FIG.

Thus, in controlling the motor 13, when the steering torque is increased to the right, the motor 13 is turned on at point a, and a pressure of 1001a is applied to the motor 710 (point b).

When the steering torque is further increased and the steering torque reaches the 0 point, the current in the slip clutch 14 begins to fill up and increases approximately logarithmically with respect to the increase in the steering torque, reaching 100% current (point d).
. Conversely, when the torque is decreased, the current of the slip clutch 14 decreases from point d, and becomes 0% at point 0. When the torque further decreases to point e, the motor 13 is turned off and the applied voltage becomes zero (point F). Almost the same control is performed in the left direction as well. As shown in FIG. 3, the characteristics of the specular clutch 14 are such that the transmission torque, that is, the specular torque increases substantially proportionally to the clutch current. Therefore, as shown in FIG. 4, the torque increases, and when it reaches point a, a pressure of loo width' is applied to the motor, so the motor begins to rotate and the torque is further increased, causing the torque to change from the 0 point to the current of the slipping clutch 14. , the output torque to the worm shaft 15 gradually increases, and the auxiliary torque corresponding to the force applied to the handle 1 is applied to the worm wheel shaft 16, the electromagnetic clutch 17, and the second pinion shaft 18. This is transmitted to the second rack tooth portion 6b through the handle 1, and the handle 1 becomes lighter. The above is an explanation of the operation of the device when automatic parking is stopped.

Then automatic! When the vehicle is in a running state, as shown in the steering torque vs. slipping clutch current characteristic diagram shown in Fig. 5, the N current value stored in advance corresponding to the steering torque and vehicle speed is used.
The vehicle clutch current is controlled. In the magnetic clutch applied voltage characteristic diagram of the vehicle speed vs. vehicle speed and vehicle speed when the control torque is constant as shown in Fig. 6, when the steering torque is set as a constant condition, it decreases in a stepwise manner inversely to the increase in the downward speed. At point f, no current flows through the slip clutch 14 even if rotational force is generated in the handle 1.

When the vehicle speed further increases and reaches point g, the electromagnetic clutch 17
Also off, the worm wheel axis 16,! : Since the second pinion shaft 18 is disengaged, the driver who turns the steering wheel 1 experiences steering without auxiliary bias.

〔Effect of the invention〕

As explained above, according to the present invention, in order to eliminate the sense of incompatibility due to changes in steering torque when the vehicle moves from a stop to a running state, the '1tTifi type control of the vehicle clutch current and motor applied voltage is applied to the steering wheel. Since the operation is carried out based on the values stored in advance corresponding to the torque and vehicle speed, the control program of the control unit can be used without changing each element of the device, and there is no strange feeling.
The present invention provides a method for controlling the nosewar steering that provides a good steering feel and is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a motor-based power steering system according to an embodiment of the present invention, FIG. 2 is a block diagram of a control unit, FIG. Figure 4 shows the steering torque vs. motor applied voltage and slip clutch current characteristics when the helmet is stopped, Figure 5 shows the steering torque vs. slip clutch current characteristics when the vehicle speed is changed, and Figure 6 shows the characteristics when the control torque is constant. FIG. 7 is a flowchart of the control program, which is a characteristic diagram of the slipping clutch current versus vehicle speed and the voltage applied to the electromagnetic clutch versus vehicle speed. DESCRIPTION OF SYMBOLS 1... Handle, 3... Torque sensor, 9... Control unit), 9a... Steering torque measuring means,
9b...Vehicle speed 611j constant means, 9C...Motor applied voltage determining means corresponding to heavy speed, 9d...Motor applied voltage determining means, 9e...Clutch current storage means corresponding to vehicle speed, 9f
...Clutch current determining means, 9g...Motor applied voltage control means, 9h...Clutch current control means, 91.
...t'Mi clutch control means, 10...-1st speed sensor, 13... Motor, 14... Electromagnetic slip clutch, 17... Electromagnetic clutch. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. Agent Masuo Oiwa-1c+1 QIQ? □Electric layer 11 Nizubeli Gratuna Den, 5L 14 Figure 6 Figure 7 Procedural amendment (voluntary) 5

Claims (1)

[Claims] In an automobile steering system, there is a torque sensor that detects the rotational force of the steering wheel, a vehicle speed sensor that detects the vehicle speed, a control unit that receives signals from the vehicle speed sensor and the torque sensor, and a control unit that receives the signals from the vehicle battery. In a motor-driven power steering device equipped with a DC motor driven via a DC motor and an electromagnetic slip clutch connected to the output shaft of this motor and whose output current is controlled by a control unit, Steering torque measuring means for measuring steering torque, vehicle speed measuring means for measuring vehicle speed based on input from a vehicle speed sensor, and motor applied voltage storage means corresponding to vehicle speed for storing and storing voltage applied to the motor corresponding to vehicle speed and steering torque. and motor applied voltage determining means for determining the motor applied voltage based on the applied voltage value read from the vehicle speed corresponding motor applied voltage storage means corresponding to the vehicle speed and steering torque, and an electromagnetic slip clutch current corresponding to the vehicle speed and steering torque. a clutch current storage means corresponding to the vehicle speed that stores the memory, and a clutch current determining means that determines the clutch current based on the clutch current value read from the clutch current storage means corresponding to the vehicle speed corresponding to the vehicle speed and the steering torque;
A motor applied voltage control means for controlling the motor applied voltage based on the output of the motor applied voltage determining means, and a clutch current control means for controlling the current of the electromagnetic slip clutch based on the output of the clutch current determining means. Features a motor-driven power steering control method.