JPH0930437A - Power driven pump type power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure a proper steering feeling by driving and controlling a DC brushless motor for driving a hydraulic pump with an ideal motor revolving speed according to a car speed so as to reduce power consumption. SOLUTION: A DC brushless motor 12 is used as a power motor for driving a hydraulic pump for supplying pressure oil to a power cylinder. This motor is driven and controlled by using a detecting signal from its own rotor position detecting means 13 so as to obtain a desired motor revolving speed according to a car speed detected by a car speed detecting means 16. For example, in order to reduce power consumption caused by motor driving, a car speed is controlled by a motor revolving speed characteristic such that a motor revolving speed is reduced by increasing a car speed at a specified car speed value or over and at a value lower than the specified car speed a motor revolving speed is maintained constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system that obtains steering assist force (hereinafter referred to as steering assist force or assist force) by supplying fluid pressure to a power cylinder in response to steering operation of a steering wheel. In particular, the present invention relates to an electric pump type power steering device that drives a fluid pressure pump, which is a fluid pressure source, using a DC brushless motor (hereinafter referred to as a DC brushless motor or a brushless motor).

[0002]

2. Description of the Related Art In a power steering apparatus, an electric pump type in which a hydraulic pump, which is a fluid pressure pump, is driven by an electric motor and a required assist force is obtained by a hydraulic pressure according to traveling conditions such as vehicle speed is known. For example, the actual development Sho 56-673
Various proposals have been made, including No. 91 publication. In such a conventional device, a DC brush motor is generally used as the electric motor.

In such an electric pump type power steering apparatus, the pump is driven and controlled only when hydraulic pressure needs to be supplied by controlling the number of revolutions of the electric motor for driving the pump according to the vehicle speed. Therefore, it is possible to prevent excessive supply of pressure oil as compared with a conventional engine-driven pump of an automobile, eliminate unnecessary driving of the pump, suppress heat generation of the pump itself, and configure a hydraulic circuit. It is possible to improve durability by eliminating unnecessary operation of each component. Also, the location of the pump is not limited to the vicinity of the engine and there is no restriction on the space.

However, in the above-mentioned conventional apparatus, it is general to drive and control the pump driving motor at a constant voltage. For example, if a sudden load is applied to the power supply system, the motor rotational speed will decrease. If the required hydraulic pressure cannot be obtained and the load is small, the pump rotation speed increases and the hydraulic pressure is unnecessarily supplied.

Therefore, for example, Japanese Patent Laid-Open No. 6-26305
Japanese Patent Laid-Open No. 2 (1994) discloses a motor for driving a pump as a control device for a power steering device by controlling a voltage so that a required number of rotations can be maintained and a required amount of pressure oil flow can be secured. A structure is disclosed in which a pressure oil flow rate can be supplied in a necessary and sufficient state without waste.

That is, in this conventional example, the control device is
It is composed of a voltage indicating means for indicating and controlling the applied voltage of the motor, a current detecting means for detecting a current value of the motor, and an applied voltage correcting means for applying the current value to the voltage indicating means as a correction voltage value for the applied voltage. are doing. Then, in this conventional example, the motor voltage value is fed back to the target set voltage of the motor, and the motor current value is used as a correction value of the motor voltage and added to the motor target voltage value to maintain the required pump flow rate. It is configured to perform the control.

In other words, in this conventional example, the current value flowing through the motor is proportional to the motor torque for generating the fluid pressure. Therefore, the fluid pressure is detected by the motor current value, and the required fluid pressure is the motor rotation speed. The constant rotation control that maintains the minimum required number of rotations is performed by utilizing the fact that is indicated by. By doing this, unlike the conventional constant voltage control,
Even in a heavy load area, the required rotation speed is secured, the required flow rate is obtained, and the problem of insufficient assist force does not occur. In addition, wasteful consumption in an area with a light load is eliminated.

Further, in Japanese Patent Laid-Open No. 6-263046, the assist force is controlled according to the traveling state by changing the rotation speed of the motor according to the traveling state such as vehicle speed, steering angle, steering speed and the like. In particular, there is disclosed a configuration for solving a problem that gives a feeling of strangeness to a steering operator, in which the motor rotation once decreases and then rises again when the steering wheel is suddenly turned back.

That is, in this conventional example, the relationship between the vehicle speed sensor, the steering angle sensor, the steering speed detecting means for detecting the steering angular speed based on the detection signal, the vehicle speed, the steering angle, and the voltage applied to the motor. And a vehicle speed control characteristic storage means that stores the relationship between the vehicle speed and the voltage applied to the motor. Further, a first applied voltage search means for searching the steering angle control characteristic storage means for a voltage applied to the motor based on the signal from the vehicle speed sensor and the signal from the steering angle sensor, and to the motor based on the signal from the vehicle speed sensor. Second applied voltage searching means for searching the vehicle speed control characteristic storage means for the applied voltage of No. 1, and the first applied voltage searching means for the voltage applied to the motor in accordance with the increase in the steering angular velocity detected by the steering speed detecting means. A control transfer means for gradually transferring to the second applied voltage search means is provided.

With the above-described structure, when the steering angular velocity is relatively low, for example, the rotation speed of the motor is reduced near the neutral position to reduce the power consumption, and the steering is performed even when the steering wheel is steered. A sudden change in feeling is prevented and the assist force is controlled according to the running condition.

[0011]

However, in the conventional example disclosed in Japanese Patent Laid-Open No. 6-263052, the motor voltage and the motor current are fed back, and the steering speed is input by the steering sensor.
Since the drive control of the motor is performed, there is a problem that the control of the motor is complicated.

Further, in the conventional example disclosed in Japanese Patent Laid-Open No. 6-263046, the drive speed of the motor is controlled by inputting the vehicle speed, the steering angle, and the steering angular speed to reduce the power consumption for driving the motor. There is no feedback means for driving the motor. Therefore, in this conventional example,
Even if the vehicle speed is constant and the driving conditions are the same, there is a problem that the motor rotation speed fluctuates due to a load fluctuation accompanying a change in steering resistance, resulting in a change in steering force.

Further, in the above-mentioned conventional example, a brush motor is generally used as the electric motor as described above, and the brush is electrically connected to the rotor which is a rotating body in the motor by a commutator on the motor shaft. It is a structure that makes sliding contact with the (commutator). However, recently, the development of electric vehicles has progressed, and as an on-vehicle battery to be mounted in such an electric vehicle, 12V in a general gasoline vehicle is used.
Or, instead of a 24 V DC power supply, for example 96-60
A DC high-voltage power supply of 0 V, and especially about 200 to 400 V is used, and the brushed motor has the following problems.

That is, in order to drive a brushed DC motor, which is an electric motor, with the above-mentioned DC high-voltage power supply, a DC-DC converter has conventionally been used for stepping down the voltage, and this converter converts the voltage down to 12V. It is necessary to adopt a structure in which conversion is performed and power is supplied to this via a control device. However, when such a DC-DC converter is used, a large amount of heat is generated during voltage conversion, power loss is large, and energy conversion efficiency is poor. In addition, the number of parts required for the device including such a DC-DC converter is large and the structure is complicated, resulting in a large scale of the entire device.

Therefore, a control device for driving the above-described electric motor for driving the pump by a DC high voltage power supply is used, and the power supply voltage from the DC high voltage power supply is pulse width modulated (hereinafter It is considered that the voltage is directly applied to the pump driving motor under the control of PWM).

However, in the above brush motor,
Since the brush that comes into sliding contact with the commutator will be worn, regular maintenance of this brush is required.This is a problem in terms of the life of the brush part and the noise of this brush part due to the brush and commutator. Was needed. In particular, such a problem is an important problem in a motor-driven pump that has a relatively large chance of being driven at high load and high rotation. For example, it is necessary to perform frequent maintenance and replace the brush when the mileage of the automobile reaches a certain distance.

Further, in such a motor with a brush, there is a risk of causing a problem that the rotation of the motor is stopped because the contact between the brush and the commutator is broken as an accidental failure. Further, when the brush is worn as described above, the abrasion powder of the brush enters the slot portion of the commutator,
There is also a problem that the motor output decreases due to a short circuit, etc.In consideration of such a point, the pump drive motor described above is used according to the vehicle traveling conditions such as the vehicle speed, the steering angle and the steering angular speed. It is desired to take some measures so that drive control can be performed in an optimum state.

The present invention has been made in view of the above circumstances, and when the hydraulic pump for obtaining the steering assist force is driven by the DC brushless motor, the rotor position detecting means included in the motor itself is provided. In consideration of the motor rotation speed information obtained from the vehicle speed detection means, the vehicle speed information from the vehicle speed detection means, and the steering angle and steering angular speed information obtained from the steering state detection means, the motor rotation speed characteristic with respect to the vehicle speed is optimized to obtain an ideal characteristic or this. The purpose of the present invention is to obtain an electric pump type power steering device that reduces the power consumption by driving the motor by a simple drive control based on the characteristics similar to the above, and that does not impair the steering feeling during steering. .

[0019]

In order to meet such a demand, an electric pump type power steering apparatus according to the present invention drives a fluid pressure pump that feeds fluid pressure to a power cylinder that generates a steering assist force. As the electric motor, a DC brushless motor equipped with rotor position detecting means for detecting the position of the rotor in the direction of rotation of the motor is used, and the vehicle speed information from the vehicle speed detecting means for detecting the traveling speed of the vehicle and the rotor position are used. Control means is provided for controlling the motor rotation speed of the DC brushless motor by inputting the motor rotation speed information obtained from the detection signal from the detection means.

In the electric pump type power steering apparatus according to the present invention, the motor speed information obtained by the rotor position detecting means of the DC brushless motor and the vehicle speed information from the vehicle speed detecting means are input to the control means. The DC brushless motor is drive-controlled with such a characteristic that the motor rotation speed is decreased by increasing the vehicle speed above a predetermined vehicle speed value, and the motor rotation speed is kept constant below the predetermined vehicle speed value.

Further, in the electric pump type power steering apparatus according to the present invention, the motor speed information obtained by the rotor position detecting means of the DC brushless motor and the vehicle speed information obtained from the vehicle speed detecting means are input to the control means. , The motor rotation speed is decreased by increasing the vehicle speed above the first predetermined vehicle speed value, the motor rotation speed is decreased by decreasing the vehicle speed below the second predetermined vehicle speed value, and the first and second predetermined vehicle speed values are decreased. The DC brushless motor is configured to drive and be controlled with a characteristic that the motor rotation speed is constant during the period, and in the drive control of the DC brushless motor, the motor is increased by increasing the vehicle speed above the first predetermined vehicle speed value. A characteristic is selected such that the rotation speed is smoothly decreased and that the motor rotation speed is smoothly decreased by decreasing the vehicle speed at the second predetermined vehicle speed value or less. It is use.

Further, the electric pump type power steering apparatus according to the present invention is provided with a steering condition detecting means for detecting a steering angle and a steering angular velocity involved in the steering operation. By inputting the angular velocity information into the control means together with the motor rotation speed information obtained by the rotor position detection means of the DC brushless motor and the vehicle speed information from the vehicle speed detection means, the vehicle speed for controlling the drive of the DC brushless motor with respect to the vehicle speed is controlled. It is configured to correct the motor rotation speed characteristic.

According to the present invention as described above, in order to obtain the steering assist force by driving the fluid pressure pump of the power steering apparatus using the DC brushless motor,
Motor speed characteristics with respect to the ideal vehicle speed obtained by considering the relationship between vehicle speed and steering characteristics, the relationship between vehicle speed and hydraulic pressure generated by the pump, the volumetric efficiency of the pump, the specific discharge amount of the pump, the pressure receiving area of the power cylinder, etc. In order to approximate this, the brushless motor is designed to reduce power consumption by the vehicle speed information or the motor rotation speed characteristic with respect to the vehicle speed obtained according to the vehicle speed information and the steering angle and the steering angular velocity information. Drive control is performed, and a necessary and sufficient characteristic for steering assist force is obtained.

The above-mentioned fluid pressure pump corresponds to a hydraulic pump in the case of a hydraulic power steering system, for example. The rotor position detecting means is, for example, an encoder or a rotational position detecting sensor that can detect the rotational position of the rotor, which is the rotating body in the DC brushless motor, and the motor rotation speed information can be obtained from the detection signal. This is the part that serves as a motor rotation speed detection device. Further, the vehicle speed detecting means is a vehicle speed sensor attached at an appropriate position and capable of detecting the vehicle speed.

The predetermined vehicle speed value, the first predetermined vehicle speed value, and the second predetermined vehicle speed value are arbitrary set values when the vehicle speed increases or decreases, and the first predetermined vehicle speed value and the second predetermined vehicle speed value. The vehicle speed value is a case where the first predetermined vehicle speed value is higher. Further, the steering status detecting means is a steering angle sensor attached to a steering shaft or the like that can detect the operation of the steering wheel and that can detect the steering angle and the steering angular velocity. The motor control means is, for example, a control device including a signal controller and a power controller.

[0026]

1 is a schematic diagram showing an embodiment of an electric pump type power steering apparatus according to the present invention,
In the figure, reference numeral 1 is a main body of a hydraulic power steering apparatus, and a tie rod 3 connected to left and right steered wheels 2 and 2 of an automobile (not shown) via a knuckle arm is provided. Although not shown in detail in the drawings, the apparatus main body 1 includes a flow passage switching valve that switches a hydraulic flow passage by a steering shaft 5 transmitting a steering operation with a steering handle 4 as is widely known. A transmission unit for transmitting the steering operation to the tie rod 3 side and a power cylinder for generating a steering assist force according to the steering operation by introducing hydraulic pressure into either the left or right chamber are provided.

Reference numeral 7 is an automobile, for example, an electric vehicle (EV)
The main battery for EV drive installed in
It is composed of a DC high-voltage power supply of 600 V, especially about 200 to 400 V (described as 336 V in this embodiment). Reference numeral 8 is a low-voltage power supply for driving auxiliary equipment such as a wiper, which is, for example, a 12V auxiliary battery.

Reference numeral 10 denotes a motor-driven oil pump portion for sending pressure oil as fluid pressure to the apparatus main body portion 1, for example, a vane type oil pump (not shown) and an oil tank 11 having a casing covering the periphery thereof. A DC brushless motor 12 as an electric motor that is connected to this and drives the pump is configured.

Numeral 13 is an encoder which is provided in the DC brushless motor 12 and is a rotor position detecting means for detecting the rotor rotational position of the DC brushless motor 12, and is attached to the end of the motor 12 opposite to the tank 11. The encoder 13 functions as a motor rotation speed detection device that can obtain motor rotation speed information from the detection signal. In the figure, 14a and 14b are a supply side pipe for supplying the pressure oil from the oil pump to the apparatus main body 1 and a return side pipe to the tank 11.

A signal controller 15 is connected to the auxiliary battery 8 and constitutes a control means for controlling the brushless motor 12.
5, a vehicle speed information signal from a vehicle speed sensor and a motor rotation speed information signal of the motor 12 from the encoder 13 are sent to 5. Reference numeral 17 is a power controller for supplying a drive current to the DC brushless motor 12 by the signal controller 15.
The power controller 17 is a part that constitutes a control means of the brushless motor 12 together with the signal controller 15.

The power controller 17 is configured to be connectable to the main battery 7 via the operation switch 18. Then, when the switch 18 is turned on, the power controller 17 is configured to apply a drive voltage to the DC brushless motor 12 according to a signal from the signal controller 15.

Then, in this way, the brushless motor 12
By driving the pump, a pump (not shown) is operated in a required state, and pressure oil having a required pressure is fed to the power cylinder through a flow passage switching valve (not shown) in the apparatus body 1. As a result, when steering the vehicle in the low speed traveling range, the assist force is increased to lighten the steering force, and when steering in the medium to high speed traveling region, the assist force is decreased to increase the steering force. The assist force during steering of the steering wheel 4 can be controlled.

According to the present invention, in the electric pump type power steering apparatus having the above-mentioned structure, the DC brushless motor 12 is used as the electric motor for driving the hydraulic pump, and the vehicle speed detecting means for detecting the traveling speed of the vehicle is used. Vehicle speed information from a certain vehicle speed sensor 16 and motor rotation speed information obtained from a detection signal from an encoder 13 as rotor position detecting means for detecting the rotational position of a rotor (not shown) in this motor 12 are input. Thus, the signal controller 15 and the power controller 17 are provided as control means for controlling the motor rotation speed of the DC brushless motor 12.

According to the present invention, the DC brushless motor 12 is added to the signal controller 15 which is the control means.
By inputting the motor speed information from the encoder 13 and the vehicle speed information from the vehicle speed sensor 16, as shown in FIG. 2, the motor speed N is decreased by increasing the vehicle speed V at a predetermined vehicle speed value V0 or higher. , Has a characteristic such that the motor rotation speed N is constant at a predetermined vehicle speed value V0 or less, D
The C brushless motor 12 is configured to be driven and controlled.

That is, if the motor rotation speed is controlled with such a characteristic shown in FIG. 2, the control is not complicated and can be easily performed, although the motor rotation speed N is controlled only by the vehicle speed V. It In particular, in such a motor rotation speed characteristic with respect to the vehicle speed of FIG. 2, not only is it possible to secure a sufficient flow rate of pressure oil for steering when the vehicle is stopped or running at low or medium speeds, but also to obtain a sufficient steering assist force. Since the motor speed is controlled only by the vehicle speed with simple control, the steering wheel 4 can be operated in all steering states regardless of the load.
It enables steering without getting caught in.

The characteristics shown in FIG. 2 are low,
The number of revolutions is feedback-controlled so that the number of revolutions during medium-speed running is constant, so regardless of the size of the load,
A constant flow rate can be maintained according to the vehicle speed. Therefore, only the required flow rate according to the vehicle speed can be discharged, and the control with the minimum power consumption of the battery 7 becomes possible.

Furthermore, according to the present invention, the control means (1
5, 17) encoder 1 of DC brushless motor 12
3 by inputting the motor rotation speed information from the vehicle speed sensor 16 and the vehicle speed information from the vehicle speed sensor 16, as shown in FIG. 3A, the motor rotation speed N is increased by increasing the vehicle speed at the first predetermined vehicle speed value V1 or more. The motor rotation speed N is decreased by decreasing the vehicle speed below the second predetermined vehicle speed value V2, and the motor rotation speed N is kept constant between these first and second predetermined vehicle speed values V1 and V2. The DC brushless motor 12 may be configured to be driven and controlled with various characteristics.

In this way, compared to the characteristics shown in FIG. 2 described above, the motor rotation speed N can be reduced at low speed and during stationary steering while the vehicle is stopped. Can be reduced. Moreover, in such a configuration, the maximum number of rotations in the entire number of rotations N of the motor is reduced, so that the motor 12 can be downsized. Here, the first predetermined vehicle speed value V1 and the second predetermined vehicle speed value V2 have a relationship of V1> V2.

Further, in the drive control of the brushless motor 12 based on the characteristics shown in FIG.
As shown in (b), at the first predetermined vehicle speed value V1 or higher, the motor speed N is smoothly decreased by increasing the vehicle speed V,
At the second predetermined vehicle speed value V2 or less, a characteristic may be selected such that the motor speed N is smoothly decreased by decreasing the vehicle speed V.

In this way, by making the relationship between the vehicle speed V and the motor speed N smooth, it is possible to smoothly change the motor speed N with respect to the vehicle speed V when the vehicle speed V suddenly changes. Since the discharge flow rate from the pump is the same, the steering feeling is less likely to be uncomfortable, and the steering feeling can be improved.

For the characteristic of the motor speed N with respect to the vehicle speed V for controlling the motor 12 for driving the pump described above, it is necessary to test the steering state of each part constituting the power steering apparatus including the steering link system of the actual vehicle. Can be obtained by

FIG. 4 is premised on the characteristics shown in FIGS. 3 (a) and 3 (b) described above, and in addition to this, in consideration of the steering situation in the vehicle, that is, the steering angle and the steering angular velocity, the motor speed is changed. It is considered that N is corrected to make the characteristics closer to the steering situation in the actual vehicle. Here, in such an embodiment, for example, a steering angle sensor attached to the steering shaft 5 or the like shown in FIG. 1 may be used as the steering state detecting means for detecting the steering angle and the steering angular velocity involved in the steering operation. .

Then, the steering angle and the steering angular velocity information from the steering angle sensor are sent to the signal as a control means together with the motor speed information from the encoder 13 for detecting the rotor position of the brushless motor 12 and the vehicle speed information from the vehicle speed sensor 16. By inputting to the controller 15 and the power controller 17, the motor rotation speed characteristic with respect to the vehicle speed for controlling the drive of the brushless motor 12 is corrected. As a result, the steering characteristics (steering feeling) can be optimized.

In particular, according to such a configuration, in addition to the function and effect described in the above-mentioned embodiment, the motor rotation speed N is controlled by the steering angle and the steering angular velocity signal.
Regardless of the vehicle speed V, the motor rotation speed N in the straight traveling state
Therefore, the power consumption can be further reduced as compared with the case where only the vehicle speed described above is supported. Further, in such a configuration, since the motor rotation speed N increases during steering or during quick steering,
The discharge flow rate from the pump does not become insufficient, and a proper steering feeling can be obtained without giving a driver a feeling of being caught during steering.

FIG. 5 is a block diagram for obtaining the characteristics shown in FIG. 4 described above. The same or corresponding parts as in FIG. To do. In FIG. 5, reference numeral 21 is a steering angle sensor for obtaining the above-mentioned steering angle and steering angular velocity, and P
Is a pump driven by the motor 12.

Further, the signal controller 15 as the control means has the map and characteristics in the frame shown by the reference symbol S1, and the formula for obtaining the final target motor rotational speed N shown at S2, that is, N = NM. XKxK 'is calculated, and based on the result obtained, pulse width modulation control (PWM control) is performed on the power controller 17 to drive and control the motor 12 at a required rotation speed. There is.

The above-mentioned signal controller 15
Is a basic characteristic map of vehicle speed-target motor rotation speed (NM), vehicle speed, steering angle (θ) -correction coefficient (K) determination characteristic of target motor rotation speed N0, vehicle speed, steering angle speed (θ ')-target motor rotation The map is provided so that the correction coefficient (K ') determining characteristic of the number N0 can be selected. Then, by this, each characteristic and the characteristic in which the correction coefficient is added can be selected and the required control can be performed.

That is, FIG. 6 is a characteristic diagram showing the target motor rotation speed N with respect to the vehicle speed V. In the figure, a is the characteristic when the vehicle is not steering, and b is the vehicle speed V-motor. The basic characteristics of the target speed NM are shown. In addition, Va, Vb
Indicates an arbitrary vehicle speed value. Further, FIG. 7A shows the characteristic of determining the correction coefficient K of the vehicle speed V-the target motor speed N0, and the characteristic correction coefficient K changes as the steering angle increases. The correction coefficient K maintains the relationship of K ≦ 1. Further, FIG. 7B shows the steering angle θ-target motor rotation speed N.
The correction coefficient K of 0 is shown, and the correction coefficient K of the characteristic changes as the vehicle speed increases. For example, when the steering angle is θa and the vehicle speed is Va, the correction coefficient is Ka, and when the steering angle is 0, it is Ka0.

FIG. 8 shows the steering angular velocity θ'-target motor rotation speed N.
It is a characteristic diagram for selecting the determination characteristic of the correction coefficient K ′ of 0, and the correction coefficient changes between K′a and “1” at an arbitrary steering angular velocity θ′a. ing. The correction coefficient K ′ at this time maintains the relationship of K ′ ≧ 1.
Therefore, as is clear from these relationships, K ×
The relationship of K ′ ≦ 1 is established, and the motor rotation speed N in a state where all the conditions are taken into consideration is N = NM × K × K ′
Is set to a value that maintains the relationship of.

Based on the above-described conditions, the characteristic of the motor rotation speed N with respect to the vehicle speed V is in the state shown in FIG. 9, and an arbitrary characteristic is selected between the basic characteristic and the straight traveling characteristic. As a result, the motor rotation speed is determined in consideration of the steering angle and the steering angular velocity, so that it is possible to drive the motor according to the traveling situation.

Here, a flow chart for setting the motor rotation speed in consideration of the above-mentioned steering angle and steering angular velocity will be described.
As shown in FIG. 10, S101, S102, and S103.
Then, the target motor rotation speed NM is determined, the corrected target motor rotation speed N is calculated from the correction coefficients K and K ′, and the encoder 13
The actual rotation speed NR is calculated and compared with the target rotation speed N. Then, the absolute value ΔN between N and NR is calculated in S104, and when ΔN is large, the process returns in S106 and returns to S101. When the absolute value ΔN is small, the deviation from the target rotational speed is corrected so as to be ΔN or less, and then the process returns.

Needless to say, the present invention is not limited to the structure described in the above-mentioned embodiment, and the shape, structure, etc. of each part of the apparatus may be appropriately modified or changed. For example, in the above-described embodiment, the encoder 13 detects the position of the rotor of the DC brushless motor 12, which is an electric motor.
However, it may be performed by a sensor using a Hall IC, and an appropriate modification can be considered as the rotor rotational position detecting means.

[0053]

EXAMPLE A DC high-voltage power source used as an EV driving main battery 7 has a voltage range of 96 to 600V, and
A battery of 36 V is used, and this battery is directly connected to the DC brushless motor 12 via the power controller 17 and is driven by PWM control by a signal from the signal controller 15 to drive the pump P. There is.

[0054]

As described above, according to the electric pump type power steering apparatus according to the present invention, the position of the rotor in the rotational direction is detected as the electric motor for driving the fluid pressure pump which is the source of the steering assist force. And a motor speed information obtained by using the vehicle speed information from the vehicle speed detecting means for detecting the traveling speed of the vehicle and the detection signal from the rotor position detecting means. Based on, the brushless motor is driven and controlled at the required number of revolutions,
Despite the simple configuration, the following excellent effects are achieved.

That is, according to the present invention, the detection signal from the rotor position detecting means possessed by the brushless motor itself is skillfully utilized to reduce the motor rotation speed by increasing the vehicle speed above a predetermined vehicle speed value. By controlling the motor rotation speed to be constant below a predetermined vehicle speed value, the wasteful supply of fluid pressure from the pump is stopped in order to obtain steering assist force, which actually drives the pump drive motor. It is possible to reduce the power consumption of the in-vehicle battery for driving this motor, according to the use status of the motor.

Particularly, if the motor speed is controlled with such a characteristic, the control is not complicated but can be easily performed, although the motor speed is controlled only by the vehicle speed. With such characteristics, not only can a sufficient flow rate of pressure oil be ensured for steering when the vehicle is stopped, or that the vehicle is traveling at low or medium speeds, a sufficient steering assist force can be obtained, and the motor rotation can be performed only by the vehicle speed with simple control. Since the number is controlled, it is possible to perform steering without giving a feeling of being caught on the steering wheel in any steering state regardless of the load.

Further, with such characteristics, the power consumption can be reduced because the number of revolutions is constant, especially when traveling at low and medium speeds, and since the number of revolutions is fed back, the vehicle speed can be controlled regardless of the load. It is possible to maintain a constant flow rate.

Further, according to the present invention, when the vehicle speed is equal to or higher than the first predetermined vehicle speed value, the motor rotational speed is decreased by increasing the vehicle speed, and when the vehicle speed is equal to or lower than the second predetermined vehicle speed value, the motor rotational speed is decreased by reducing the vehicle speed. By keeping the rotation speed constant between these first and second vehicle speed values, it is possible to reduce the motor rotation speed at low speed and during stationary steering while the vehicle is stopped, and reduce the power consumption by that amount. can do. Moreover,
With such a configuration, the maximum number of rotations of the total number of rotations of the motor is reduced, so that the size of the motor can be reduced.

Further, in the above-mentioned characteristics, the motor rotation speed is smoothly decreased by increasing the vehicle speed above the first predetermined vehicle speed value, and the motor rotation speed is smoothed by decreasing the vehicle speed below the second predetermined vehicle speed value. By reducing
It is possible to smoothly change the motor rotation speed with respect to the vehicle speed when the vehicle speed suddenly changes, and the discharge flow rate from the pump is also the same, so that the driver does not feel uncomfortable when steering, and the steering feeling is improved. be able to.

Further, according to the present invention, in addition to the control of the motor rotation speed according to the vehicle speed described above, the motor rotation speed is corrected by the steering angle and the steering angular velocity signal to optimize the steering characteristics. In addition to the above-mentioned effects, the steering angle,
By controlling the motor rotation speed by the steering angular velocity signal, the motor rotation speed can be reduced in a straight traveling state at any vehicle speed, so the power consumption is further reduced as compared with the case where only the vehicle speed described above is supported. be able to. Further, since the motor rotation speed increases during steering or when the steering is performed quickly, the discharge flow rate from the pump does not become insufficient, and the steering feeling can be obtained without causing a feeling of being caught during steering. .

Further, according to the present invention, since the brushless motor is used for driving the pump, wear and failure caused by this are unlikely to occur, and the operational reliability is high. Further, unlike the brushed motor, there is no noise problem in the brush portion, the rotor can be smoothly rotated in the motor, and the pump can be efficiently driven. In particular, in such a brushless motor, sparks are not generated in the brush portion such as with a brush, and therefore, it is optimal to use a high-voltage main power source.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall schematic configuration showing an embodiment of an electric pump type power steering apparatus according to the present invention.

FIG. 2 is a characteristic diagram showing a motor rotation speed characteristic with respect to a vehicle speed when the control unit controls the DC brushless motor that drives the oil pump in FIG.

3A and 3B are characteristic diagrams showing modified examples of the motor rotation speed characteristic with respect to the vehicle speed shown in FIG.

FIG. 4 is a characteristic diagram showing a modification of the motor rotation speed characteristic with respect to the vehicle speed shown in FIGS. 2 and 3.

FIG. 5 is a block diagram for obtaining the characteristics in FIG.

FIG. 6 is a characteristic diagram showing a characteristic of a target motor rotation speed with respect to a vehicle speed for deriving the characteristic of FIG.

FIG. 7: Correction coefficient K for vehicle speed, steering angle-target motor speed
2A is a characteristic diagram showing a case where the steering angle is a parameter, and FIG. 7B is a characteristic diagram showing a case where a vehicle speed is a parameter.

FIG. 8 is a correction coefficient K ′ of steering angular velocity-target motor rotation speed.
It is a characteristic view showing the determination characteristics of.

FIG. 9 is a characteristic diagram showing a final target motor rotation speed characteristic when FIGS. 6 to 8 are integrated.

10 is a flowchart for explaining the embodiment in FIGS. 4 and 5. FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Device main body part of hydraulic power steering device, 2 ... Steering wheel, 4
... Steering handle, 5 ... Steering shaft, 7 ... Main battery, 8 ... Auxiliary battery, 10 ... Oil pump part, 11 ... Oil tank, 12 ... DC brushless motor, 13 ... Encoder (rotor functioning as motor rotation speed detection means Rotational position detecting means), 15 ... Signal controller, 16 ... Vehicle speed sensor (vehicle speed detecting means), 17 ...
Power controller, 18 ... Operation switch, 21 ... Steering angle sensor, P ... Pump.

Claims (5)

[Claims] 1. An electric pump type power steering apparatus, wherein a fluid pressure pump is driven by an electric motor to generate a steering assist force by feeding fluid pressure to a power cylinder in response to a steering operation. As the electric motor for driving the pressure pump, a DC brushless motor having a rotor position detecting means for detecting the position of the rotor in the rotation direction of the motor is used, and the vehicle speed from the vehicle speed detecting means for detecting the traveling speed of the vehicle is used. The electric pump type power is provided with control means for controlling the motor rotation speed of the DC brushless motor by inputting information and motor rotation speed information obtained from the detection signal from the rotor position detection means. Steering device. 2. An electric pump type power steering apparatus, wherein a fluid pressure pump is driven by an electric motor, and fluid pressure is fed to a power cylinder in response to a steering operation to generate a steering assist force. As the electric motor for driving the pressure pump, a DC brushless motor having a rotor position detecting means for detecting the position of the rotor in the rotation direction of the motor is used, and the vehicle speed from the vehicle speed detecting means for detecting the traveling speed of the vehicle is used. The DC brushless motor is provided with control means for controlling the motor rotation speed of the DC brushless motor by inputting information and motor rotation speed information obtained from the detection signal from the rotor position detection means. Motor speed information and vehicle speed detection means obtained by the rotor position detection means By inputting these vehicle speed information, the DC brushless motor has a characteristic that the motor rotation speed is decreased by increasing the vehicle speed above a predetermined vehicle speed value and the motor rotation speed is kept constant below the predetermined vehicle speed value. An electric pump-type power steering device characterized by drivingly controlling a vehicle. 3. An electric pump type power steering apparatus, wherein a fluid pressure pump is driven by an electric motor and fluid pressure is fed to a power cylinder in response to a steering operation to generate a steering assist force. As the electric motor for driving the pressure pump, a DC brushless motor having a rotor position detecting means for detecting the position of the rotor in the rotation direction of the motor is used, and the vehicle speed from the vehicle speed detecting means for detecting the traveling speed of the vehicle is used. The DC brushless motor is provided with control means for controlling the motor rotation speed of the DC brushless motor by inputting information and motor rotation speed information obtained from the detection signal from the rotor position detection means. Motor speed information and vehicle speed detection means obtained by the rotor position detection means By inputting these vehicle speed information, the motor rotation speed is decreased by increasing the vehicle speed above the first predetermined vehicle speed value, and the motor rotation speed is decreased by decreasing the vehicle speed below the second predetermined vehicle speed value, and An electric pump type power steering apparatus, characterized in that the DC brushless motor is drive-controlled with a characteristic that the motor speed is kept constant between the first and second predetermined vehicle speed values. 4. The electric pump type power steering apparatus according to claim 3, wherein the motor rotational speed is smoothly decreased by increasing the vehicle speed when the vehicle speed is equal to or higher than the first predetermined vehicle speed value, and the vehicle speed is reduced when the vehicle speed is equal to or lower than the second predetermined vehicle speed value. An electric pump-type power steering apparatus, characterized in that a DC brushless motor is drive-controlled by a control means with a characteristic that the number of rotations of the motor smoothly decreases. 5. The electric pump type power steering apparatus according to claim 1, claim 2, claim 3 or claim 4, wherein steering condition detecting means for detecting a steering angle and a steering angular velocity involved in the steering operation is provided. The steering angle and the steering angular velocity information from the steering state detection means are input to the control means together with the motor rotation speed information obtained by the rotor position detection means of the DC brushless motor and the vehicle speed information from the vehicle speed detection means. An electric pump-type power steering apparatus for correcting a motor speed characteristic with respect to a vehicle speed for driving and controlling a DC brushless motor.