JPS58156457A - Power steering controller - Google Patents

Abstract

PURPOSE:To obtain the stability of steering, by detecting a rotary speed of a motor for driving a pump and controlling an electric current conducted in said motor so as to obtain its speed of a prescribed value then holding the motor to a fixed speed in no relation to the change of a load. CONSTITUTION:When a vehicle is in running operation at a certain car speed, the car speed is detected by a car speed detecting means 24 to input a voltage signal V in a value corresponding to the car speed to a comparator circuit 43. At this running operation, if a steering wheel 11 is operated by at least the prescribed steering force, a switching circuit 50 is turned ON by an output of a steering force feeding means 23 to conduct an electric current in an armature winding 32 through a relay 46 and rotate a motor 21. Then a voltage signal M in a value corresponding to a motor speed is input to a comparator circuit 43 from a speed detecting means 25. The both signals V, M are compared in this comparator circuit 43 to control the electric current to stop its conduction to a field winding 33 for M>V while start the conduction for M<V.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering control device, and more particularly, to a control device that is provided in a power steering device in which a pump is driven by a motor and performs feedback control on the rotational speed of the motor.

Recent power steering devices use internal control factors such as the steering force applied to the steering wheel, the steering angular velocity of the steering wheel, or the fluid pressure discharged by the pump, in order to reduce power consumption and improve the steering performance of the vehicle. External control factors such as vehicle speed or engine load are used to control the steering assist force generated.

In a power steering device having a motor that drives a pump, the steering assist force is generally controlled by controlling the rotation speed of the motor. The present applicant has also developed a control device shown in the specification of Japanese Utility Model Application No. 56-188343 regarding a power steering device for driving a pump by a motor.

The power steering control device disclosed in Utility Model Application No. 56-188343 includes a steering angular velocity detection means for detecting the steering angular velocity of a steering wheel and outputting a signal corresponding to the steering angular velocity; A control circuit is provided for supplying current to the motor in accordance with the output signal of the means. This control device controls the current value applied to the motor to decrease as the steering angular velocity of the steering wheel increases, and the actuator of the motor operates in large quantities when the steering angular velocity of the steering wheel is large. The fluid is supplied to improve responsiveness and generate sufficient steering force. Also,
If the steering angular velocity of the steering wheel is small,
The motor rotates at a relatively low speed and the pump only delivers a small amount of working fluid, thereby reducing the power consumed by the power steering system.

However, in the power steering control device according to this prior application, the control circuit supplies a current to the motor with a value uniquely determined by a control signal such as the detected steering angular velocity, without considering the load on the motor. Since it has a one-way control (open roof 'control) configuration that conducts electricity, if the load on the pump or motor changes, the motor rotation speed will also change, making it possible to accurately control the motor rotation speed, that is, to control the fluid discharge amount of the pump. The problem was that it was impossible to control. That is, when the rotation speed of the motor fluctuates and the discharge amount of the pump fluctuates, there is a problem in that the steering assist force generated in the power steering device fluctuates, making the steering of the steering wheel unstable.

The present invention has been made with attention to such problems, and includes a rotation speed detection means for detecting the rotation speed of a motor and outputting a signal corresponding to the rotation speed, and an output signal of the rotation speed detection means. An object of the present invention is to provide a power steering control device equipped with a control circuit that controls the value of current applied to the motor so that the motor maintains a predetermined rotational speed based on the input of the current. .

The present invention will be explained below based on the drawings.

1 to 4 are diagrams showing one embodiment of the present invention.

First, to explain the configuration, ``old'' is a steering wheel, and ``12H+31'' are steering wheels.

Steering wheels (121 (!31 are each tie rod a)
It is connected to the steering gear box 06) via the shaft (15) and a ball joint (not shown). The illustrated power steering device is a rack-and-pinion type steering device, and as is well known, the steering gear box U61 includes a rack-and-pinion steering gear mechanism connected to the steering wheel (older) and a rack-and-pinion steering gear mechanism connected to the steering gear mechanism. a power cylinder that is connected to increase the manual steering force applied to the steering wheel (11); a control pulp that rotates together with the steering wheel (old steering wheel) to change the flow rate and flow direction of fluid supplied to the power cylinder; is stored.

The power/ring in this steering box Qll is connected to the conduit Q71 (1110
Pump A is connected to hot water. This pump 01 pressurizes the working fluid in the reservoir CD (see FIG. 2) and supplies it to the power cylinder, and is driven by a shunt-wound electric motor Cal+. Electric motor (2D is a control circuit (described later) that controls its field winding and armature winding (described later)
is connected to the control box (in which the control box is housed). This control box also includes a steering force detection means t231 (steering detection means) which is installed near the steering device and detects the steering force applied to the steering wheel 0D, and which is proportional to the speed of the vehicle. A vehicle speed detecting means 04) that outputs a pulse signal with the number of pulses determined by the number of pulses is connected to a rotation speed detecting means (c) provided on the electric motor circle and detecting the rotation speed of the motor C)11.

In addition, the steering force detection means CI! 3, the steering of the steering wheel (11) is determined based on the magnitude of the steering force applied to the steering wheel (II), and this steering can also be determined based on the steering angle of the steering wheel OIJ.

The rotation speed detection means (251) that detects the rotation speed of the electric motor (2I) has a configuration as shown in FIGS. 2 and 3, for example. An example is shown in which the electric motor (21+) is integrally provided. The rotor (7) is stored in a rotating manner.
It has an armature winding (3) that rotates integrally with the rotating shaft (rotating shaft c31 fixed to 3D), and a field winding (3?A is fixed to the cylindrical member of the housing 4). A disk (34) that rotates with the rotating shaft (3υ) is fixed to the right side of the rotating shaft 6υ in the figure.This disk (b) is electrically connected to the rotating shaft (3υ) as shown in detail in FIG. An electrical conductor (to) is fixed to a part of the main body (35) made of an insulator in the rotational direction.In addition, the end cover G!6) on the right side of the housing (2) in the figure , a holder (37) having a hole opening in the direction shown in the disk figure is fixed.A bottle-shaped brush seal is slidably housed in the 3-way hole of this boulder along with a spring field. This plan (5
8I is biased to the left in the figure by a spring (to), and its left end is pressed against the disk (b). The conductor (to) of this disk (b) is, for example, grounded, and
The brush (to) is connected to a power source not shown. therefore,
This brush (to) comes into contact with the conductor (g) as the disk (2) rotates, and outputs one pulse signal for each rotation of the disk (b). These disc diagrams, holder 1
．． 3η.

The spring (to) and plan ■ are connected to the electric motor (21
1 constitutes the rotation speed detection means (g).

The control circuit provided in the control box has a configuration as shown in FIG.

In the same figure, (c) CI! 4) (to) respectively the above-mentioned steering force detection means, vehicle speed detection means 5 rotation speed detection means,
521 (33) indicates the armature winding and field winding of the electric motor 3υ.

As shown in the figure, one end of the armature winding of the electric motor (2IJ) is grounded, and the other end is connected to the relay (4
119 is connected to the power supply via a normally open contactor (46a), and also to the field winding II! One end of n is grounded, and the other end is connected to an armature current control circuit to be described later.

The vehicle speed detection means (241) is connected to the comparison circuit (43) via the frequency-voltage conversion circuit Cυ ゛ and the amplifier circuit (42). The signal having the number of pulses is converted into a signal having a voltage value corresponding to the vehicle speed and output to the amplifier circuit (42). Similarly, the comparison circuit (43) is amplified with the output characteristics shown in FIG. 6, and is output to the rotation speed detection means I25. The output signal is converted by the frequency-voltage conversion circuit (44) into a signal having a voltage value proportional to the rotation speed of the electric motor shaft υ, and is further amplified by the amplifier circuit according to the output characteristics shown in Fig. 7, which will be described in detail later. is input to the comparator circuit (43).
3b), and the comparator (43a) is an amplifier circuit (4υ
(44), the comparator (43b) connects the output signal of the amplifier circuit (44J) and the reference voltage (Vc) to the resistor (44).
A predetermined voltage (el) divided by I't1) (R2) is input. The comparator (43a) includes an amplifier circuit (421 (45)
1] Output output signals V) and (M) are compared, and when the signal (V) is higher than the signal (M), a signal (P) with a predetermined voltage value is output, and the signal (V) becomes the signal ( M) When it is below, the output signal is set to zero. The amplifier circuit shown in Figures 6 and 7 (
As is clear from the output characteristics of 421 (45), the vehicle speed (
■1) In the vehicle speed range where the output signal of the frequency-voltage conversion circuit 0υ corresponding to the above is (V+') or more, the value of the signal (V) is (
el) and is smaller than the lowest value (el) of the signal (M), so the output signal of the comparator (43a) is always zero in the above vehicle speed range. On the other hand, in the rotation speed range of the motor (211) where the signal (M) exceeds (C2), the maximum value of the signal (V) is (C2), so in this case as well, the comparator (4
The output of 3a) is always zero. The comparator (43b) outputs a signal (P) of a predetermined voltage value when the value of the signal (M) is less than or equal to (el), and otherwise the output signal is zero. When the current amplification circuit (48) is connected to the power supply f471, its output end is connected to the field winding of the electric motor ZIJ.
When the signal (P) is input from the comparator circuit (44), the field winding IfIJ is energized from the power source (44), and when the zero signal is input, the field winding (P) is connected to the ) is stopped.These frequency voltage conversion circuits 0υ (4a,
The amplifier circuit (42) t451, the comparison circuit (43) and the current amplifier circuit (48) constitute a field current control circuit (40).

The steering force detection means is connected to a switching circuit. This switching circuit 6C has one end grounded and the other end connected to a power source (47) via a solenoid (46b) of relay 0e and an ignition switch (151)
). This relay closes the contactor (46a) when the solenoid (46b) is energized, and connects the armature winding (3) of the electric motor Qυ to the power supply (46a).
7). Moreover, the switching circuit (50) is
When the output signal value of the steering force detection means t231 is greater than or equal to a predetermined value, that is, when the manual steering force applied to the steering wheel OD is greater than or equal to the set value, the connection state is established, and the output signal value of the steering force detection means (231 is less than the predetermined value). In other words, when the manual steering force applied to the steering wheel 0υ is less than the set value, the switching circuit 50 is in a disconnected state. When a signal indicating that the force is above a predetermined value is input, the solenoid (46b) of the relay unit is energized to close the motor/tactor (46a), so that the armature winding C33 of the electric motor 3υ is turned on. (Connected with 4η.

These relays and switching circuits (50) constitute five armature current control circuits, and furthermore, this armature current control circuit ci3 is connected to the aforementioned field current control circuit (49).
together with the control circuit (41).

Next, the action will be explained.

The power steering device exemplified in this embodiment is configured to be vehicle speed sensitive and includes a vehicle speed detection means Q4), and the steering assist force generated is set to be small in a high vehicle speed range and large in a low vehicle speed range.

Therefore, the electric motor (21) driving the pump Ql
The rotational speed (R,) is set to decrease as the vehicle speed (V) increases, as shown by the broken line in Fig. 8, and to maintain the minimum rotational speed (Rmin) above the vehicle speed (vl). has been done.

Further, the electric motor Cυ used in the illustrated power steering device is a shunt-wound motor. Therefore, the driving torque (T) and rotational speed (
I() has characteristics as shown in FIG. 9 with respect to the current value (1) applied to the field winding. That is, the driving torque ('r) increases as the current value (1) increases, and the rotation speed (R) decreases as the current value (I) increases. Therefore, in this example control device, the current value (I) applied to the field winding (c) of the electric motor C911 is
is controlled to be thicker in high vehicle speed ranges (and smaller in low vehicle speed ranges).

Now, when the vehicle is running at a certain speed, the vehicle speed detection means detects the vehicle speed, and as mentioned above, a voltage signal (V) of a value corresponding to the vehicle speed is input to the comparison circuit (4). do.

Here, when the steering wheel Ql) is not being steered, that is, when the steering force applied to the steering wheel 01) is less than a predetermined value, the switching circuit (5) is in a disconnected state, and the relay ( 46) solenoid (46b) is not energized and contactor = (46)
a) is open. Therefore, the armature winding (3 power) of the electric motor l2Il is cut off from the power supply (47), and the electric motor C1l is stopped.For this reason, the rotation speed detection means (
The signal (M) input from the comparator circuit (43) has a value (el) corresponding to zero rotation speed.The comparator circuit (43) then compares both signals (V) (M). Therefore, the current amplification circuit (c) outputs a signal (P) that increases the rotation speed from the power source (47) to the electric motor (21).
1 field winding (c) is energized.

In this way, when the steering wheel 01) is not operated, the armature winding 04 of the electric motor (211)
is not energized and the electric motor (211 does not rotate),
The power consumed by the power steering device is reduced.

Furthermore, when the steering wheel U is operated with a steering force equal to or greater than a predetermined steering force, the armature winding S2 of the electric motor Qυ is energized and the motor D rotates, as described above. Therefore, the rotation speed detection means t25+ detects this rotation speed, and a voltage signal (M) having a value corresponding to the rotation fl(l(:)) is input to the comparison circuit (c). A signal (V) corresponding to the vehicle speed is input to the comparison circuit (43). Therefore, the comparison circuit (4J) compares the two input signal (V) (M) values and determines the signal value. (V)
The output is set as a signal (P) or zero depending on the magnitude of (M). That is, when the current amplification circuit (481) receives the signal (P), the current amplification circuit (481)
33) is energized, the rotation speed of motor C)11 increases,
When the signal (M) is lower than the signal (V), the comparison circuit C3
When the signal from M
) becomes lower than the signal (V), energization starts again.

By repeating such energization and de-energization of the field winding, the average current value energized to the field winding increases or decreases. Therefore, as shown by the solid line in FIG. 8, the electric motor Qυ always rotates at a rotational speed corresponding to the vehicle speed to drive the pump a. For this reason, the fluid supplied from the pump u-sickle to the power cylinder of the power steering device changes in accordance with the vehicle speed, with a small amount at high speeds and a large amount at low speeds, and the steering force generated by the power cylinder varies depending on the vehicle speed. It is small at high speeds and large at low speeds.

As described above, the control circuit t40 of the power steering control device according to the present invention receives the rotational speed signal of the electric motor Cυ and adjusts the rotational speed of the electric motor (21) so that this rotational speed signal coincides with the vehicle speed signal. For feedback control,
Even if the load on the pump Ql or the motor (21) fluctuates due to changes in the valve opening of the control pulp, etc., the rotational speed of the electric motor Qυ always has a value corresponding to the vehicle speed, and the power Since fluctuations in the steering assist force generated by the steering device do not occur, it is possible to obtain comfortable steering performance.

Furthermore, even if the vehicle speed changes while the steering wheel αυ is being steered, the signal (V) corresponding to the vehicle speed input to the comparator circuit 03 changes its value, causing the rotational speed of the motor c21) to change. change.

Therefore, even if the steering resistance changes due to a change in vehicle speed, the driver can always obtain a constant steering angle with a constant steering force corresponding to the vehicle speed.
Get a comfortable steering feel.

In addition, in a shunt motor used in a power steering device, the current value passed through its armature winding is usually 5.
The current value passed through the field winding is approximately 2 to 3 amperes. Therefore, as shown in this embodiment, if the current value flowing through the three field windings is controlled, the current amplification circuit (4gI) becomes relatively inexpensive and compact.

As described above, according to the present invention, there is provided a power steering device in which the steering force applied to the steering wheel is increased by the fluid discharged by the pump driven by the motor and transmitted to the steered wheels. a rotation speed detection means for detecting the rotation speed and outputting a signal corresponding to the rotation speed; and a current for supplying current to the motor so that the output signal of the rotation speed detection means is input and the motor maintains a predetermined rotation speed. Since the motor is configured with a control circuit that controls the value, the rotational speed of the motor, that is, the steering assist force generated by the power steering device, remains constant regardless of changes in the motor load, resulting in stable steering of the steering wheel. can get.

In addition, in this embodiment, a vehicle speed detection means for detecting the vehicle speed is provided, and the control circuit is configured to perform feedback control of the motor rotation speed in accordance with the vehicle speed, so that the steering assist force generated by the power steering device is always Since the value corresponds to the vehicle speed, the vehicle speed sensitivity is improved and a good steering feeling can be obtained.

Furthermore, in this embodiment, a steering force detection means for detecting the steering force applied to the power steering is provided, and the motor is controlled to turn ON/OFF based on the magnitude of this steering force, so that no power is consumed by the power steering device. This reduces the amount of power required to drive the vehicle, improving the fuel efficiency of the vehicle.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an outline of a power steering control device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the motor of the power steering device shown in FIG. 4 is a block diagram showing the power steering control device shown in FIG. 1, FIG. 5 is a diagram showing details of the power steering control device, and FIG. The diagram shows the amplifier circuit (42)
FIG. 7 is a diagram showing the output characteristics of the amplifier circuit (4ω), FIG. 8 is a diagram showing the rotation speed characteristics of the motor of the power steering device shown in FIG. The figure is a diagram showing the torque and rotational speed characteristics with respect to field current of the shunt motor used in the power steering device shown in Fig. 1. Old) Steering wheel, C21 (131...
・Steering wheel, 091...pump, C11
... electric motor, B3) ... steering force detection means (steering detection means), 1241 ... vehicle speed detection means, (2) ... rotation speed detection means, B2 ... armature winding,
Connection...field winding, tall)...control circuit,
(49)...Field current control circuit, (52...Armature current control circuit. Patent applicant: Nissan Motor Co., Ltd. Patent attorney: Ariga Gun - Department, Figure 7, Figure 8, Figure q)

Claims (1)

[Claims] +11 In a power steering device that increases a steering force applied to a steering wheel using fluid discharged by a pump driven by a motor and transmits the increased steering force to the steered wheels, the rotation speed of the motor is detected. a rotation speed detection means that outputs a signal corresponding to the rotation speed; and a control circuit that receives the output signal of the rotation speed detection means and controls a current value applied to the motor so that the motor maintains a predetermined rotation speed. A power steering control device comprising: (2) The predetermined rotation speed is set to be high in a low vehicle speed range and low in a high vehicle speed range.
The power steering control device described in . (3) The power steering system according to claim 11 or claim 2, wherein the control circuit energizes the motor to drive the motor only when the steering wheel is steered. IJ 7g control device.