JP2000168604A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out smooth steering by stopping speed-increasing control of an electric actuator at the time when a holding state of a steering angle is detected by a steering angle holding state detection means and by speed- increasing-controlling the electric actuator at the time when a power steering device is steered by a specified angle from the holding state of the steering angle. SOLUTION: When steering auxiliary force is not required as in the case where a steering angle is in a holding state at a steering angle of a constant range regardless of what the steering angle from a steering neutral position is, speed-increasing control of an electric motor 14 comes to be in a stopped state, and rotation of the electric motor 4 is completely stopped. Consequently, driving of the electric motor 14 is restrained in the requisite minimum, and it is possible to reduce energy required to store in a battery 7 by an alternator, etc. Additionally, as it is possible to receive the steering auxiliary force in the case where the steering auxiliary force is required, thus it is possible to carry out smooth steering without deteriorating steering feeling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering apparatus for generating a steering assist force by a pressure fluid from a pump driven by an electric actuator.

[0002]

2. Description of the Related Art Conventionally, as a power steering apparatus, for example, a power steering apparatus described in Japanese Patent Application No. 8-230707 is known. The power steering apparatus of this conventional example is a power steering apparatus including a hydraulic actuator that generates a steering assist force by pressure oil from a pump driven by an electric actuator, wherein a means for detecting a steering angle of a steering wheel; Means for detecting the steering angular velocity, and, when the detected steering angle satisfies one of the conditions of not less than a preset reference steering angle and the detected steering angular velocity is not less than a preset reference steering angular velocity, via the electric actuator. And means for increasing the speed of the pump.

[0003]

However, the conventional power steering apparatus described above has the following problems. That is, as described above, if the steering angle is equal to or larger than the preset reference steering angle, the electric actuator is maintained in the driving state, and thus, in the state where the steering angle is maintained to the extent that the steering angle exceeds the reference steering angle, Although the steering is not being performed, the electric actuator is maintained in a driven state although the steering assist force of the power steering is not actually required, and the battery is greatly consumed by wasteful power consumption. In addition, even when steering assist force is required on a road surface with a large resistance, when the steering is gently performed so that the steering angle and the steering angular speed do not exceed the reference values, the drive of the electric actuator remains stopped. Therefore, the steering assist force cannot be obtained. It is conceivable to solve the above problem by setting the reference value.However, if the value of the reference steering angle is set to a large value so that the electric actuator is stopped when the steering is maintained, the reference steering angular velocity If the steering is performed slowly enough not to exceed the steering angle, no steering assist force will be generated until the steering angle exceeds the reference steering angle. Will be. To cope with this, if the value of the reference steering angular velocity is set to a small value, the electric actuator is driven even when the steering wheel is turned little by little in a substantially straight running state where the steering assist force is unnecessary. When the vehicle is running, the electric actuator is almost in a driven state, so that the energy saving effect is hardly obtained. By the way, when the drive of the electric actuator is controlled to be on / off by setting the steering angular velocity as a threshold value, as shown in FIG. 7, when the steering angle is slow enough to finally exceed the steering angular velocity threshold value (marked by ○) (in the case of D) Is turned on only after a large turning from a neutral point (steering angle), the steering feeling is such that the steering assist force does not act forever even though the steering force is heavy.

The present invention has been made in view of the above-mentioned conventional problems. By minimizing the driving of the electric actuator to a necessary minimum, the energy required for storing the electric power in the battery by an alternator or the like is obtained. Provided is a power steering device that can reduce the steering force and can receive the steering assist force when the steering assist force is required, thereby enabling smooth steering without deteriorating the steering feeling. That is the purpose.

[0005]

According to a first aspect of the present invention, there is provided a power steering device for supplying a fluid under pressure, an electric actuator for driving the fluid pump, and a steering device. A steering force assisting mechanism for assisting a steering force by supplying a pressurized fluid from the fluid pump according to the load of the fluid pump, a steering angle detecting means for detecting a steering angle, and a steering angle detected by the steering angle detecting means. Control means for increasing the speed of the electric actuator in accordance with the steering angle, and a steering angle holding state detection method for detecting a holding state of the steering angle detected by the steering angle detection means. Means for controlling the electric actuation when the control means detects the holding state of the steering angle by the steering angle holding state detecting means. The speed increasing control of eta is stopped,
When the steering is steered by a predetermined angle from the holding state of the steering angle, the speed of the electric actuator is controlled to increase. In the power steering device according to the second aspect, in the power steering device according to the first aspect, the control unit may be configured to determine that the steering angle holding state detection unit detects the steering angle by a predetermined angle after the steering angle holding state continues for a predetermined time. The electric actuator is configured to perform speed-up control when being steered. According to a third aspect of the present invention, there is provided the power steering device according to the first or second aspect, further comprising a vehicle speed detecting unit detecting a vehicle speed, wherein the control unit detects the vehicle speed detected by the vehicle speed detecting unit. Is greater than or equal to a predetermined value, and when the steering angle detected by the steering angle detecting means is equal to or greater than a predetermined steering angle from the neutral position of the steering, the steering angle holding state detection means detects the steering angle. The means is configured to prohibit execution of the detection processing. According to a fourth aspect of the present invention, there is provided the power steering apparatus according to any one of the first to third aspects, wherein the electric actuator is stopped except during the speed increase control of the electric actuator. .

[0006]

In the power steering apparatus according to the first aspect, as described above, the speed increase control of the electric actuator is turned on / off depending on whether or not the steering operation is performed at the predetermined angle from the state in which the steering angle is held. When the steering is maintained beyond the reference steering angle and no steering assist force is required, the speed increase control of the electric actuator is stopped, so the driving of the electric actuator is minimized. As a result, it is possible to reduce the energy required for storing electricity in the battery by the alternator or the like. In addition, even when the steering angle exceeds the reference steering angle, the speed increase control of the electric actuator is resumed when the steering operation is further performed at a predetermined angle. As a result, smooth steering can be performed without deteriorating the steering feeling. Further, as described above, when the steering assist force is not required even if the reference steering angle is not set large, the speed increase control of the electric actuator is stopped. When a steering assist force is required, the steering assist force can be obtained when the steering angle exceeds the reference steering angle. Furthermore, even when the steering wheel is turned little by little in a substantially straight running state where no steering assist force is required, if the steering angle from the holding state of the steering angle is equal to or smaller than the reference steering angle, the electric power is not increased even if the steering speed is high. Since the speed increase control of the actuator is maintained in a stopped state, an energy saving effect is obtained. In the power steering apparatus according to the second aspect, in the power steering apparatus according to the first aspect, the electric actuator is activated only when the holding state of the steering angle is continued for a predetermined time and thereafter when the steering angle is steered by a predetermined angle. Since the speed increase control is performed, for example, in a case where the holding and steering of the steering is frequently repeated, such as when entering a garage, the electric actuator does not repeatedly increase and decrease the speed frequently. The generation of heat and noise from the electric actuator is prevented. According to a third aspect of the present invention, in the power steering device according to the first or second aspect, the vehicle speed is equal to or more than a predetermined value, and the steering angle is equal to or more than the predetermined steering angle from the neutral position of the steering. In this case, the execution of the steering angle holding state detection process by the steering angle holding state detection means is prohibited, whereby the speed increase control of the electric actuator based on the detection of the steering angle holding state is stopped. For example, if the vehicle is making a substantially steady circular turn at a certain vehicle speed, the steering angle is maintained, but a sharp steering operation may be required during the turn. Since the speed increase control is maintained, the steering feeling does not deteriorate. Further, in the power steering device according to the fourth aspect, in the power steering device according to any one of the first to third aspects, the electric actuator is stopped except when the speed increase control of the electric actuator is performed, so that an energy saving effect is obtained. It will be even higher.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a system diagram showing a power steering device according to an embodiment of the present invention. FIG. 2 is a system block diagram showing control contents of the power steering device according to the embodiment of the present invention. A pinion type power steering gear, 2 is a steering wheel, 3 is a motor driver, 4 is a microcomputer (control means), 5 is a steering angle sensor, 6 is a vehicle speed sensor, 7 is a battery, and 8 is a relay.

The rack-and-pinion type power steering gear 1 steers a vehicle by converting the rotational movement of a steering wheel 2 into a linear movement of a rack. The power steering gear 1 includes a steering force assisting mechanism. A hydraulic cylinder (a hydraulic pump) for supplying pressurized oil to the hydraulic control valve 12, a hydraulic pump (fluid pump) 13 for supplying pressurized oil to the hydraulic cylinder, An electric motor (electric actuator) 14 for driving the hydraulic pump 13 and a reservoir tank 15 for storing hydraulic oil are provided.

Next, of the control operations of the microcomputer 4,
The content of the steering detection process in the steering angle holding state detecting means for detecting the holding state of the steering angle will be described with reference to the flowchart of FIG.

First, in step 101, the steering angle is sampled at a period A. In step 102, it is determined whether or not the change in the steering angle is gradual. Since the vehicle is not in the steering-holding state, one flow is completed.

On the other hand, the determination in step 102 is YES
If (the steering angle change is gradual), the process proceeds to step 103 for starting the steering holding state determination process, and then to step 104.
Then, after the steering angle is sampled in the cycle B, the process proceeds to step 105.

In step 105, it is determined whether or not the amount of change in the steering angle is in the steering-holding state. If NO (the amount of change exceeding the steering-holding state), the vehicle is not in the steering-holding state. ,
Proceeding to step 106, after clearing the steering elapse time counter, this ends one flow.

On the other hand, the determination in step 105 is YES.
If it is (steering-maintenance state area), the process proceeds to step 107 for starting the steering-holding state determination process, and after adding the steering-holding elapsed time counter, proceeds to step 108.

In step 108, it is determined whether or not the steering maintenance time has elapsed or longer. If NO (less than the steering maintenance time), the vehicle is not in the steering maintenance state. To end.

On the other hand, if the determination in step 108 is YES
If it is (a state in which the steering maintenance time has elapsed), the process proceeds to step 109, where it is determined that the steering is in the maintenance state, and the steering angle at that time is stored in the memory (if an old value remains, the new value is replaced with a new value). ) At the same time, after setting the motor off flag,
This completes one flow.

Next, the contents of the processing for prohibiting the execution of the steering holding detection processing based on the vehicle speed and the absolute steering angle will be described with reference to the flowchart of FIG. First, in step 201, the vehicle speed is 20 k
m / h or more is determined, and NO (20 km / h
In the case of (less than), it is necessary to stop the speed-up control of the electric motor 14 by executing the steering-holding detection processing of FIG. 3, so that one flow is completed.

On the other hand, the determination in step 201 is YES
If it is (20 km / h or more), the routine proceeds to step 202, where it is determined whether or not the absolute steering angle is in a straight road area. Since it is necessary to stop the speed-up control of the electric motor 14 by execution, this completes one flow.

On the other hand, the determination in step 202 is NO.
When the vehicle is not in a straight road area (ie, during a steady circular turning at a certain vehicle speed), a sudden steering operation may be required. In such a situation, the speed increase control of the electric motor 14 is stopped. Is not preferred, so step 203
And the prohibition of the execution of the steering detection processing is performed.

Next, the content of the speed-up control on / off determination process of the electric motor 14 performed based on the result of the steering-holding detection process of FIG. 3 and the result of the steering-holding detection process execution prohibition process of FIG. A description will be given based on the flowchart of FIG.

First, at step 301, the steering angle is sampled at a cycle C. At step 302, the amount of change from the steering angle stored at step 209 in FIG. Then, it is determined whether or not the steering is performed at a predetermined threshold or more.
After setting the motor-on flag for starting the speed increasing control of No. 4, the process proceeds to step 305, and if NO (less than the predetermined threshold value), the process directly proceeds to step 305.

In step 305, after executing the steering holding detection process, the process proceeds to step 306, where it is determined whether or not the motor-on flag is set. If YES, the process proceeds to step 307 to turn on the electric motor 14. After starting the speed increase control, the one-time flow is completed with this.
If NO, the process proceeds to step 308.

In step 308, it is determined whether or not the motor-off flag is set. If the answer is YES, the process proceeds to step 309, in which the electric motor 14 is turned off to stop the speed increasing control. One flow is ended, and if NO, one flow is ended.

Next, the operation and effect of the power steering apparatus according to the embodiment of the present invention will be described. (A) In the steering holding state Regardless of the steering angle from the steering neutral position, when the steering assist angle is not required, such as when the steering steering angle is in the holding state in a certain range of steering angle, Electric motor 14
Is stopped, and the rotation of the electric motor 14 is completely stopped. Thus, the driving of the electric motor 14 is suppressed to a necessary minimum. Therefore, the battery 7 is charged by an alternator or the like. Energy required for this purpose can be reduced.

(B) When Steering is Above a Predetermined Threshold from Steering Hold State When Steering is Above a Predetermined Threshold from Steering Angle Holding State, the Electric Motor 14 is turned on and the speed increase control is started. Accordingly, a steering assist force can be generated. Then, even when the steering angle is further increased from the neutral position of the steering, the speed increase control of the electric motor 14 is restarted when the steering operation is further performed at the predetermined angle. Can receive the steering assist force, thereby enabling smooth steering without deteriorating the steering feeling.

As shown in FIG. 6, the steering state (steering angle) is set to a neutral point, and the relative steering angle change (steering angle) is measured from the neutral point. Since the force is generated, the steering assist force can be generated when the same amount of change or the same steering force always occurs regardless of the steering speed.

As described above, when the steering assist force is not required without setting the predetermined threshold value large,
Since the speed-up control of the electric motor 14 is stopped, even when the steering is moderate, when the steering assist force is required on a road surface having a large resistance, the steering angle exceeds the predetermined threshold value so that the steering assist force is reduced. Will be able to gain.

(C) When the Steering from the Steered State is Less than a Specified Threshold The steering from the steered state can be performed even when the steering wheel is turned little by little in a substantially straight running state where no steering assist force is required. If the angle is equal to or smaller than the predetermined threshold value, the speed-up control of the electric motor 14 is maintained in a stopped state even if the steering speed is high, so that an energy saving effect can be obtained even in such a situation. It should be noted that a high energy saving effect can be obtained by completely stopping the rotation of the electric motor 14 except during the speed-up control of the electric motor 14.

(D) When the holding and steering of the steering wheel are repeated frequently Only when the holding state is continued for a predetermined holding maintenance time or longer, the electric motor 14 increases when the steering is performed at a predetermined angle thereafter. Since the speed control is performed, for example, in a case where the holding and steering of the steering are frequently repeated, such as when entering a garage, the electric motor 14 does not repeatedly increase and decrease the speed. The generation of heat and noise of the motor 14 is prevented.

(E) Steady circular turning at a certain vehicle speed When the vehicle speed is 20 km / h or more and the absolute steering angle exceeds the straight road area, the execution of the steering maintenance detection process is prohibited. As a result, the process of stopping the speed increase control of the electric motor 14 by detecting the holding state of the steering angle is not performed. Therefore, when the vehicle is turning substantially in a steady circle at a certain vehicle speed, the steering angle becomes the holding state. However, since the speed of the electric motor 14 is controlled to be increased, the steering feeling does not deteriorate even if the steering is suddenly performed thereafter.

It should be noted that the vehicle speed is less than 20 km / h even during a substantially steady circular turning, or the vehicle speed is 20 km / h.
h, the prohibition of the execution of the steering-maintenance detection processing is released when the absolute steering angle of the steering is in a straight road area. it can.

As described above in detail, according to the power steering apparatus of the embodiment of the present invention, the driving of the electric motor 14 can be suppressed to the minimum necessary.
This makes it possible to reduce the energy required for storing electricity in the battery 7 by the alternator or the like, and to receive the steering assist force when the steering assist force is required, thereby improving the steering feeling. The effect is obtained that smooth steering is possible without deterioration.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the embodiments of the present invention, and design changes and the like can be made without departing from the gist of the present invention. The present invention is also included in the present invention.

For example, in the embodiment of the invention, the rotation of the electric motor is completely stopped except during the speed increase control of the electric motor. However, the speed increase control of the electric motor is performed in order to improve the response of the steering assist. At other times, a certain energy saving effect can be obtained even when the electric motor is driven with the minimum necessary rotation.

[0034]

As described above, in the power steering apparatus according to the first aspect of the present invention, a fluid pump for pressurizing and supplying a fluid, an electric actuator for driving the fluid pump, and a steering load are provided. A steering force assisting mechanism for assisting a steering force by supplying a pressurized fluid from the fluid pump, a steering angle detecting means for detecting a steering angle, and a steering detected by the steering angle detecting means. Control means for controlling the speed of the electric actuator in accordance with a steering angle, wherein the steering angle holding state detecting means for detecting a holding state of the steering angle detected by the steering angle detecting means is provided. The control means increases the number of electric actuators when the holding state of the steering angle is detected by the steering angle holding state detection means. The control is stopped, and the speed of the electric actuator is controlled to be increased when the steering is steered by a predetermined angle from the holding state of the steering angle, so that the driving of the electric actuator can be suppressed to a necessary minimum. This makes it possible to reduce the energy required for storing electricity in the battery by an alternator or the like, and to receive steering assist force when steering assist force is required, thereby improving the steering feeling. The effect is that smooth steering is possible without deteriorating the steering. According to a second aspect of the present invention, in the power steering apparatus according to the first aspect, the control unit determines that the steering angle holding state is detected by the steering angle holding state detection unit for a predetermined angle after the steering state is maintained for a predetermined time. By adopting the means configured to control the speed of the electric actuator when it is steered, for example, when the holding and steering of the steering is frequently repeated, such as when entering a garage, the electric The actuator does not repeatedly increase or decrease the speed, thereby preventing the electric actuator from generating heat and generating noise. According to a third aspect of the present invention, there is provided the power steering apparatus according to the first or second aspect, further comprising a vehicle speed detecting unit configured to detect a vehicle speed, wherein the control unit controls the vehicle speed detected by the vehicle speed detecting unit. When the steering angle detected by the steering angle detecting means is equal to or greater than a predetermined value and the steering angle detected by the steering angle detecting means is equal to or greater than the predetermined steering angle from the neutral position of the steering, the steering angle holding state detection means detects the steering steering angle. By adopting the means configured to prohibit the execution of the process, for example, if the vehicle has made a substantially steady circular turn at a certain vehicle speed, the steering is in a holding state,
Since a sharp steering operation may be required during a turn, the electric actuator is kept under speed increase control, and the steering feeling does not deteriorate. According to a fourth aspect of the present invention, in the power steering device according to any one of the first to third aspects, the electric actuator is stopped except during the speed increase control of the electric actuator. Thus, the energy saving effect can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a power steering device according to an embodiment of the present invention.

FIG. 2 is a system block diagram showing control contents of the power steering device according to the embodiment of the present invention.

FIG. 3 is a flowchart showing the contents of a steering detection process in steering angle holding state detecting means for detecting a holding state of a steering angle among control contents of the power steering apparatus according to the embodiment of the present invention.

FIG. 4 is a flowchart showing the contents of a control operation for inhibiting the execution of a steering-holding detection process based on the vehicle speed and the absolute steering angle in the control contents of the power steering apparatus according to the embodiment of the present invention.

FIG. 5 shows the contents of the electric motor speed-up control on / off determination processing performed based on the result of the steering detection processing and the result of the processing for prohibiting the execution of the steering detection processing in the control contents of the power steering apparatus according to the embodiment of the present invention. It is a closing flowchart shown.

FIG. 6 is a diagram for explaining an advantage in a case where the speed increase control of the electric motor is turned on / off by a relative steering angle change amount in the power steering apparatus according to the embodiment of the present invention.

FIG. 7 is a diagram for explaining a drawback in a case where on / off control of driving of an electric actuator is performed using a steering angular velocity as a threshold value.

[Explanation of symbols]

Reference Signs List 1 power steering gear 2 steering wheel 3 motor driver 4 microcomputer (control means) 5 steering angle sensor (steering angle detecting means) 6 vehicle speed sensor (vehicle speed detecting means) 7 battery 8 relay 11 power cylinder (steering force assist mechanism) 12 hydraulic control Valve (steering force assist mechanism) 13 Hydraulic pump (fluid pump, steering force assist mechanism) 14 Electric motor (electric actuator, steering force assist mechanism) 15 Reservoir tank (steering force assist mechanism)

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3D032 CC08 CC49 CC50 DA03 DA19 DA23 DB02 DC09 DC33 DC34 DE09 EA01 EB04 EB11 EC03 GG01 3D033 CA03 CA13 CA17 CA21 EB04

Claims (4)

[Claims] A fluid pump for pressurizing and supplying a fluid, an electric actuator for driving the fluid pump, and assisting a steering force by supplying a pressurized fluid from the fluid pump according to a load on a steering. A power steering system comprising: a steering force assisting mechanism; steering angle detection means for detecting a steering angle; and control means for increasing the speed of the electric actuator in accordance with the steering angle detected by the steering angle detection means. The apparatus further includes: a steering angle holding state detecting unit that detects a holding state of the steering steering angle detected by the steering angle detecting unit. The control unit determines that the steering steering angle holding state is determined by the steering angle holding state detecting unit. When it is detected, the speed increase control of the electric actuator is stopped, and when the steering angle is steered by a predetermined angle from the holding state, the electric actuator is stopped. Power steering apparatus characterized by being configured so that the actuator for speed increasing control. 2. The control device according to claim 1, wherein the control unit controls the speed of the electric actuator when the steering angle is maintained by the steering angle holding state detection unit for a predetermined time after the steering angle is maintained. The power steering device according to claim 1, wherein: 3. The vehicle according to claim 1, further comprising a vehicle speed detecting unit configured to detect a vehicle speed, wherein the control unit determines that the vehicle speed detected by the vehicle speed detecting unit is equal to or greater than a predetermined value and the steering angle detected by the steering angle detecting unit. When the steering angle exceeds a predetermined steering angle from the neutral position of the steering wheel, the steering angle holding state detecting means is configured to prohibit execution of the steering angle holding state detection process. 3. The power steering device according to 2. 4. The power steering apparatus according to claim 1, wherein the electric actuator is stopped except during the speed increase control of the electric actuator.