JP2014151878A - Hydraulic power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power steering system capable of preventing occurrence of excess power consumption in a steering sustained state.SOLUTION: An angle deviation conversion unit 54 converts an angle deviation Δθv, which is computed by an angle deviation arithmetic unit 53, into a control angle deviation Δθv' which exhibits a dead band in which the control angle deviation takes on zero when the absolute value of the angle deviation Δθv is equal to or smaller than a predetermined value. An integration element 72 computes an integration maneuver quantity by performing an integral arithmetic on the control angle deviation Δθv' computed by the angle deviation conversion unit 54. More particularly, the integration element 72 obtains a current integration maneuver quantity by adding a previous integration maneuver quantity to a value obtained by multiplying the control angle deviation Δθv' by an integral gain Ki.

Description

  The present invention relates to a hydraulic power steering apparatus.

  2. Description of the Related Art Conventionally, a hydraulic power steering apparatus that assists steering force by supplying hydraulic oil from a hydraulic pump to a power cylinder coupled to a steering mechanism of a vehicle via a hydraulic control valve is known. In a general hydraulic power steering apparatus, a hydraulic control valve is mechanically connected to a steering member such as a steering wheel via a steering shaft, and the opening degree of the hydraulic control valve is adjusted according to the operation of the steering member. Is done.

JP 2006-306239 A

As a hydraulic power steering apparatus, an apparatus that controls the opening of a hydraulic control valve by an electric motor (valve driving motor) without mechanically connecting the hydraulic control valve to a steering member has been developed. The inventors have studied a hydraulic power steering apparatus that controls a valve driving motor by feedback control, and have come to the present invention.
An object of the present invention is to provide a hydraulic power steering device capable of suppressing the occurrence of excessive power consumption in the steering holding state.

  In order to achieve the above object, a hydraulic control valve according to claim 1 is not mechanically connected to a steering member (3) to a power cylinder (16) connected to a steering mechanism (2) of a vehicle. A hydraulic power steering device (1) that generates steering assist force by supplying hydraulic oil from a hydraulic pump (23) via (14), and controls the opening of the hydraulic control valve. And a rotation angle command value setting means (52) for setting a rotation angle command value that is a target value of the rotation angle of the electric motor, and a rotation angle for detecting the actual rotation angle of the electric motor. The electric motor is fed back so that the actual rotation angle detected by the detection means (33) and the rotation angle detection means is equal to the rotation angle command value set by the rotation angle command value setting means. Feedback control means (53, 54, 72) for controlling the rotation angle, wherein the feedback control means is the rotation angle command value set by the rotation angle command value setting means and the actual rotation detected by the rotation angle detection means. Control that generates a control angle deviation having a dead zone that becomes zero when the absolute value of the angle deviation between the rotation angle command value and the actual rotation angle is equal to or less than a predetermined value A (A> 0) based on the angle. A hydraulic power steering apparatus comprising: an angular deviation generating means (53, 54); and a feedback element (72) for calculating an operation amount based on the control angular deviation generated by the control angular deviation generating means. is there. In addition, although the alphanumeric character in parentheses represents a corresponding component in an embodiment described later, of course, the scope of the present invention is not limited to the embodiment. The same applies hereinafter.

  The feedback element performs an operation on a control angle deviation having a dead zone that becomes zero when the absolute value of the angle deviation between the rotation angle command value and the actual rotation angle is equal to or less than a predetermined value A (A> 0). Thus, the operation amount is calculated. Therefore, even when a slight angle deviation occurs between the actual rotation angle and the rotation angle command value due to the detection noise of the actual rotation angle, etc. in the steering holding state, the control angle deviation is maintained at a zero value. The increase in the absolute value of the manipulated variable calculated by the feedback element can be suppressed or prevented. As a result, it is possible to suppress or prevent the motor current from fluctuating even when the rotor of the hydraulic control valve is stationary due to friction in the steered state. Thereby, it can suppress that extra power consumption generate | occur | produces at the time of a steering maintenance state.

  According to a second aspect of the present invention, the control angle deviation generating means takes a zero value when the absolute value of the angle deviation between the rotation angle command value and the actual rotation angle is equal to or less than the predetermined value A. An angle deviation is generated, and when the angle deviation is larger than the predetermined value A, a control angle deviation which takes a positive value and becomes larger as the angle deviation is larger is generated, and the angle deviation is smaller than −A. 2. The hydraulic power steering apparatus according to claim 1, wherein the hydraulic power steering apparatus is configured to generate a control angle deviation that takes a negative value and decreases as the angle deviation decreases.

According to a third aspect of the present invention, the feedback element is an integration element (72) for calculating an integral operation amount by performing an integral calculation on the control angle deviation generated by the control angle deviation generator. 3. A hydraulic power steering apparatus according to claim 1 or 2.
According to a fourth aspect of the present invention, the feedback control means includes PID control means (55) including a proportional element (71), an integral element (72), and a derivative element (73). 3. The hydraulic power steering apparatus according to claim 1, wherein at least an integral element of the elements and the differential element is configured to calculate an operation amount based on the control angle deviation. 4.

  The invention according to claim 5 is characterized in that the feedback control means includes PI control means including a proportional element (71) and an integral element (72), and at least the integral element of the proportional element and the integral element is: 3. The hydraulic power steering apparatus according to claim 1, wherein the operation amount is calculated based on the control angle deviation. 4.

FIG. 1 is a schematic diagram showing a schematic configuration of a hydraulic power steering apparatus according to an embodiment of the present invention. FIG. 2 is a control block diagram of the valve drive motor controller. FIG. 3 is a graph showing the relationship between the preset angle deviation Δθv and the control angle deviation Δθv ′. FIG. 4 is a graph showing temporal changes in the current command value and the like in the steering holding state in the valve drive motor control device shown in FIG. FIG. 5 is a control block diagram (reference diagram) of a valve drive motor control device that has been developed by the present applicant. FIG. 6 is a graph showing a setting example of the assist torque command value Ta ^* with respect to the detected steering torque Th. FIG. 7 is a graph showing a setting example of the valve opening command value θv ^* with respect to the assist torque command value Ta ^* . FIG. 8 is a graph (comparative example) showing temporal changes in the current command value and the like during the steering holding state in the valve drive motor control device shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a schematic configuration of a hydraulic power steering apparatus according to an embodiment of the present invention.
The hydraulic power steering device 1 is for applying a steering assist force to a steering mechanism 2 of a vehicle. The steering mechanism 2 is connected to a steering wheel 3 as a steering member operated by a driver for steering the vehicle, a steering shaft 4 connected to the steering wheel 3, and a tip end portion of the steering shaft 4. A pinion shaft 5 having a pinion gear 6 and a rack shaft 7 having a rack 7a meshing with the pinion gear 6 and extending in the left-right direction of the vehicle are provided.

Tie rods 8 are connected to both ends of the rack shaft 7, and the tie rods 8 are connected to knuckle arms 11 that support the left and right steered wheels 9 and 10, respectively. The knuckle arm 11 is rotatably provided around the kingpin 12.
When the steering wheel 3 is operated and the steering shaft 4 is rotated, this rotation is converted into a linear motion along the axial direction of the rack shaft 7 by the pinion gear 6 and the rack 7a. This linear motion is converted into a rotational motion around the kingpin 12 of the knuckle arm 11, whereby the left and right steered wheels 9, 10 are steered.

  A steering angle sensor 31 for detecting a steering angle, which is a rotation angle of the steering shaft 4, is disposed around the steering shaft 4. In this embodiment, the rudder angle sensor 31 detects the amount of rotation (rotation angle) of the steering shaft 4 in both forward and reverse directions from the neutral position of the steering shaft 4, and the amount of rotation from the neutral position to the right direction is detected. For example, it outputs as a positive value, and outputs the amount of rotation from the neutral position to the left as, for example, a negative value. The pinion shaft 5 is provided with a torque sensor 32 for detecting the steering torque Th.

  The hydraulic power steering apparatus 1 includes a hydraulic control valve 14, a power cylinder 17 and a hydraulic pump 23. The hydraulic control valve 14 is, for example, a rotary valve, and includes a rotor housing (not shown) and a rotor (not shown) for switching the flow direction of hydraulic oil. The opening degree of the hydraulic control valve 14 is controlled by rotating the rotor of the hydraulic control valve 14 by an electric motor 15 (hereinafter referred to as “valve driving motor 15”). The valve driving motor 15 is composed of, for example, a three-phase brushless motor. In the vicinity of the valve drive motor 15, a rotation angle sensor 33 made of, for example, a resolver for detecting the rotation angle (actual rotation angle θv) of the rotor of the valve drive motor 15 is disposed.

  The hydraulic control valve 14 is connected to a power cylinder 16 that applies a steering assist force to the steering mechanism 2. The power cylinder 16 is coupled to the steering mechanism 2. Specifically, the power cylinder 16 has a piston 17 provided integrally with the rack shaft 7 and a pair of cylinder chambers 18 and 19 defined by the piston 17. These are connected to the hydraulic control valve 14 through corresponding oil passages 20 and 21, respectively.

  The hydraulic control valve 14 is interposed in the middle of an oil circulation path 24 that passes through a reservoir tank 22 and a hydraulic pump 23 for generating a steering assist force. The hydraulic pump 23 is composed of, for example, a gear pump, is driven by an electric motor 25 (hereinafter referred to as “pump drive motor 25”), draws hydraulic oil stored in the reservoir tank 22, and supplies it to the hydraulic control valve 14. . Excess hydraulic oil is returned from the hydraulic control valve 14 to the reservoir tank 22 via the oil circulation path 24.

  The pump driving motor 25 is driven to rotate in one direction to drive the hydraulic pump 23. Specifically, the output shaft of the pump drive motor 25 is connected to the input shaft of the hydraulic pump 23, and the input shaft of the hydraulic pump 23 rotates as the output shaft of the pump drive motor 25 rotates. Thus, driving of the hydraulic pump 23 is achieved. The pump drive motor 25 is composed of, for example, a three-phase brushless motor. In the vicinity of the pump drive motor 25, a rotation angle sensor 34 made of, for example, a resolver for detecting the rotation angle of the rotor of the pump drive motor 25 is disposed.

  When the rotor of the hydraulic control valve 14 is rotated in one direction from the reference rotation angle position (neutral position) by the valve drive motor 15, the hydraulic control valve 14 passes through one of the oil passages 20 and 21. The hydraulic oil is supplied to one of the cylinder chambers 18 and 19 of the power cylinder 16 and the other hydraulic oil is returned to the reservoir tank 22. When the rotor of the hydraulic control valve 14 is rotated in the other direction from the neutral position by the valve driving motor 15, the other of the cylinder chambers 18, 19 is passed through the other of the oil passages 20, 21. Is supplied to the reservoir tank 22 and one hydraulic oil is returned to the reservoir tank 22.

  When the rotor of the hydraulic control valve 14 is in the neutral position, the hydraulic control valve 14 is in a so-called equilibrium state, and the cylinder chambers 18 and 19 of the power cylinder 16 are maintained at the same pressure when the steering is neutral. It circulates through the circulation path 24. When the rotor of the hydraulic control valve 14 is rotated by the valve drive motor 15, hydraulic oil is supplied to one of the cylinder chambers 18 and 19 of the power cylinder 16, and the piston 17 is in the vehicle width direction (the left-right direction of the vehicle). Move along. As a result, a steering assist force acts on the rack shaft 7.

  Steering angle detected by the steering angle sensor 31, steering torque Th detected by the torque sensor 32, output signal of the rotation angle sensor 33, output signal of the rotation angle sensor 34, vehicle speed Sp detected by the vehicle speed sensor 35, valve drive The output signal of the current sensor 36 for detecting the current flowing through the motor 15 is input to the control device 40 constituted by a computer. The control device 40 controls the valve drive motor 15 via the drive circuit 41 and also controls the pump drive motor 25 via the drive circuit 42.

The control device 40 includes a valve drive motor control unit 43 for controlling the drive circuit 41 of the valve drive motor 15 and a pump drive motor control unit 44 for controlling the pump drive motor 25. . Details of the operation of the valve drive motor control unit 43 will be described later.
The pump drive motor control unit 44 controls the pump drive motor 25 as follows, for example. That is, the pump drive motor control unit 44 calculates the rotation speed of the pump drive motor 25 based on the output signal of the rotation angle sensor 34. The pump drive motor control unit 44 calculates the steering angular velocity by differentiating the output value of the steering angle sensor 41 with respect to time. Next, the pump drive motor control unit 44 calculates a rotational speed command value of the pump drive motor 25 based on the steering angular speed. The rotational speed command value is set to a predetermined value when the steering angular speed is zero, and is set to a larger value as the steering angular speed is larger. Then, the pump drive motor control unit 44 controls the drive circuit 42 of the pump drive motor 25 so that the rotation speed of the pump drive motor 25 becomes equal to the rotation speed command value. The pump drive motor control unit 44 may control the drive circuit 42 so that the rotation speed of the pump drive motor 25 becomes a predetermined speed.

Before describing the valve drive motor control unit 43 in the present embodiment, a valve drive motor control device already developed by the present applicant will be described with reference to FIGS.
FIG. 5 is a control block diagram (reference diagram) of the valve drive motor control apparatus 100 already developed by the present applicant. The configuration of the hydraulic power steering device other than the valve drive motor control unit 43 is the same as the configuration shown in FIG. 1, and the valve drive motor control device 100 will be described.

The valve drive motor control device 100 includes assist torque command value setting unit 151, valve opening command value setting unit 152, angle deviation calculation unit 153, and PID (proportional) as function realizing means realized by software processing. An integral differentiation) control unit 155, a current deviation calculation unit 156, and a PI (proportional integration) control unit 157 are included.
The assist torque command value setting unit 151 is an assist torque that is a command value of assist torque to be generated by the power cylinder 16 based on the detected steering torque Th detected by the torque sensor 32 and the vehicle speed Sp detected by the vehicle speed sensor 35. Set command value Ta ^* [N · m]. Specifically, the assist torque command value setting unit 151 sets the assist torque command value Ta ^* based on a map that stores the relationship between the detected steering torque and the assist torque command value for each vehicle speed. FIG. 6 is a graph showing a setting example of the assist torque command value Ta ^* with respect to the detected steering torque Th.

As for the detected steering torque Th, for example, a torque for steering in the right direction is a positive value, and a torque for steering in the left direction is a negative value. The assist torque command value Ta ^* is a positive value when assist torque for steering in the right direction is generated by the power cylinder 16, and is a negative value when assist torque for steering in the left direction is generated by the power cylinder 16. Is done.

The assist torque command value Ta ^* takes a positive value for a positive value of the detected steering torque Th and takes a negative value for a negative value of the detected steering torque Th. When the detected steering torque Th is a minute value in the range of -T1 to T1, the assist torque is set to zero. In the region where the detected steering torque Th is outside the range of -T1 to T1, the assist torque command value Ta ^* is set such that the absolute value thereof increases as the absolute value of the detected steering torque Th increases. . The assist torque command value Ta ^* is set such that the absolute value thereof decreases as the vehicle speed Sp detected by the vehicle speed sensor 35 increases.

Based on the assist torque command value Ta ^* set by the assist torque command value setting unit 151, the valve opening command value setting unit 152 sets the target value of the opening of the hydraulic control valve 14 (the rotation angle of the valve drive motor 15). Is set to a valve opening command value (rotation angle command value) θv ^* [deg]. In this example, the rotation angle of the valve drive motor 15 when the rotor of the hydraulic control valve 14 is in the neutral position is 0 °. The rotation angle range of the rotor of the hydraulic control valve 14 is about ± 3 [deg] in mechanical angle with the neutral position as the center.

  It is assumed that the opening degree of the hydraulic control valve 14 is controlled so that assist torque for rightward steering is generated by the power cylinder 16 when the rotation angle of the valve driving motor 15 becomes larger than 0 °. On the other hand, when the rotation angle of the valve driving motor 15 is smaller than 0 °, the opening degree of the hydraulic control valve 14 is controlled so that assist torque for leftward steering is generated by the power cylinder 16. The absolute value of the assist torque generated by the power cylinder 16 increases as the absolute value of the rotation angle of the valve driving motor 15 increases.

Valve opening command value setting unit 152, based on the map storing the relation between the assist torque command value Ta ^* and the valve opening command value .theta.v ^*, sets the valve opening command value .theta.v ^*. FIG. 7 is a graph showing a setting example of the valve opening command value θv ^* with respect to the assist torque command value Ta ^* . The valve opening command value .theta.v ^*, is the assist torque command value Ta ^* of positive value takes a positive value, a negative value for negative values of the assist torque command value Ta ^*. The valve opening command value θv ^* is set such that the absolute value of the assist torque command value Ta ^* increases as the absolute value of the assist torque command value Ta ^* increases.

The angle deviation calculation unit 153 includes a valve opening command value θv ^* set by the valve opening command value setting unit 152 and a rotation angle (actual rotation angle) θv of the valve driving motor 15 detected by the rotation angle sensor 33. Deviation Δθv (= θv ^* −θv) is calculated.
The PID control unit 155 performs PID calculation (proportional integral differential calculation) on the angle deviation Δθv calculated by the angle deviation calculation unit 153. That is, the angle deviation calculation unit 153 and the PID control unit 155 constitute rotation angle feedback control means for guiding the rotation angle θv of the valve drive motor 15 to the valve opening command value θv ^* . The PID control unit 155 calculates the current command value I ^* [A] of the valve driving motor 15 by performing PID calculation on the angle deviation Δθv.

The current deviation calculation unit 156 is a deviation ΔI (= I ^* −I) between the current command value I ^* obtained by the PID control unit 155 and the motor current (actual current) I [A] detected by the current sensor 36. Is calculated. The PI control unit 157 performs a PI calculation (proportional integration calculation) on the current deviation ΔI (= I ^* −I) calculated by the current deviation calculation unit 156. That is, the current deviation calculation unit 156 and the PI control unit 157 constitute current feedback control means for guiding the motor current I flowing through the valve driving motor 15 to the current command value I ^* . The PI control unit 157 calculates a voltage command value V ^* [V] to be applied to the valve driving motor 15 by performing a PI calculation on the current deviation ΔI.

In FIG. 5, the valve driving motor 15 is described as a motor model which is a mathematical model. The motor model can be expressed as 1 / (L · s + R). R is an armature winding resistance [Ω], L is an armature winding inductance [H], and s is a differential operator (Laplace operator). It is considered that a deviation between the voltage command value V ^* calculated by the PI control unit 157 and the induced voltage E [V] is applied to the valve driving motor 15. As a result, the motor current I (actual current) [A] flows through the valve driving motor 15. This motor current I is detected by the current sensor 36 and fed back to the current deviation calculator 156.

A value obtained by multiplying the motor current I by the torque constant Kt [N · m / A] of the valve driving motor 15 is the motor torque Tm [N · m]. A value obtained by subtracting the load torque TL [N · m] required for driving the hydraulic control valve 14 from the motor torque Tm is the torque Tv [N · m] applied to the hydraulic control valve 14. A value obtained by multiplying the torque Tv by 1 / (J · s) is the motor rotation speed ω [rad / s]. J is a motor inertia [kg · m ² ], and s is a differential operator (Laplace operator). A value obtained by multiplying the motor rotation speed ω by the counter electromotive voltage constant Ke [V · s / rad] of the valve driving motor 15 is the induced voltage E [V].

Further, a value obtained by multiplying the motor rotation speed ω by 1 / s becomes the rotation angle of the valve driving motor 15. 1 / s is an integral operator. The rotation angle sensor 33 detects the actual rotation angle [deg] of the valve driving motor 15. The actual rotation angle θv detected by the rotation angle sensor 33 is fed back to the angle deviation calculation unit 153.
In this way, the valve drive motor 15 is feedback-controlled so that the opening degree θv of the hydraulic control valve 14 becomes equal to the valve opening degree command value θv ^* .

In the valve drive motor control device 100 as shown in FIG. 5, it has been found that the current command value I ^* and the actual current I may fluctuate greatly as shown in FIG.
FIG. 8 is a graph (comparative example) showing temporal changes in the current command value and the like in the steering holding state in the valve drive motor control device 100 shown in FIG. Specifically, FIG. 8 shows a temporal change in the internal pressure P, the valve opening command value θv ^* , the actual rotation angle θv, the current command value I ^*, and the actual current I in the hydraulic control valve 14 in the steering holding state ( Measured value). However, since there are many portions where the current command value I ^* and the actual current I overlap, they are drawn without distinction in FIG. Similarly, there are many portions where the valve opening command value θv ^* and the actual rotation angle θv overlap with each other, and in FIG. 8, they are drawn without distinction. From FIG. 8, it can be seen that the current command value I ^* and the actual current I are greatly changed from the time corresponding to 150 [s].

The reason why the current command value I ^* fluctuates greatly during the steering state where the angle deviation between the valve opening command value θv ^* and the actual rotation angle θv is almost zero is considered as follows. That is, in the steering holding state, the current command value I ^* converges to a value equal to or less than the current value corresponding to the friction torque acting on the rotor of the hydraulic control valve 14. When a slight angle deviation Δθv occurs between the valve opening command value θv ^* and the actual rotation angle θv due to detection noise or the like of the actual rotation angle θv in the steering holding state, the angle deviation Δθv is reduced by the action of feedback control. The current command value I ^* changes in the direction to make it zero. At this time, if the friction component acting on the rotor increases due to factors such as internal pressure fluctuations of the hydraulic control valve 14, the rotor of the hydraulic control valve 14 is stationary due to friction. However, the absolute value of the current command value I ^* greatly fluctuates as the friction component increases.

In other words, when the friction component changes in the direction of increasing in the steering holding state, the angle deviation Δθv changes due to the minute angle deviation due to the detection noise of the actual rotation angle θv and the like, and the current command and operation is repeated such value I ^* is changed, it is considered that the current command value I ^* changes. Such an operation is considered to be largely influenced by an integral element that is generated by using a cumulative value of the angle deviation Δθv as an operation amount among the proportional element, the integral element, and the derivative element included in the PID control unit 155. If there is no change in the actual rotation angle θv and only the friction component fluctuates, there is essentially no need to increase the motor current. Therefore, the fluctuation of the motor current, which is considered to be caused by the fluctuation of the friction component, causes extra power consumption.

Hereinafter, the valve drive motor control unit 43 in the control device 40 of FIG. 1 will be described in detail.
FIG. 2 is a control block diagram of the valve drive motor control unit 43. The valve drive motor control unit 43 shown in FIG. 2 has been developed to suppress fluctuations in motor current that are considered to occur due to fluctuations in the friction component acting on the rotor of the hydraulic control valve 14.

The valve drive motor control unit 43 includes, as function realizing means realized by software processing, an assist torque command value setting unit 51, a valve opening command value setting unit 52, an angle deviation calculation unit 53, and an angle deviation conversion. A unit 54, a PID (proportional integral derivative) control unit 55, a current deviation calculation unit 56, and a PI (proportional integral) control unit 57 are included.
The operations of the assist torque command value setting unit 51, the valve opening command value setting unit 52, the angle deviation calculation unit 53, the current deviation calculation unit 56, and the PI control unit 57 are respectively the assist torque command value setting unit 151, FIG. The operations of the valve opening command value setting unit 152, the angle deviation calculation unit 153, the current deviation calculation unit 156, and the PI control unit 157 are the same. The valve drive motor control unit 43 is different from the valve drive motor control device 100 of FIG. 5 in that an angle deviation conversion unit 54 is provided.

The assist torque command value setting unit 51 is an assist torque that is a command value of assist torque to be generated by the power cylinder 16 based on the detected steering torque Th detected by the torque sensor 32 and the vehicle speed Sp detected by the vehicle speed sensor 35. Set command value Ta ^* [N · m]. The operation of the assist torque command value setting unit 51 is the same as that of the assist torque command value setting unit 151 in FIG.

The valve opening command value setting unit 52 is based on the assist torque command value Ta ^* set by the assist torque command value setting unit 51, and a valve opening command value (rotation) that is a command value of the opening of the hydraulic control valve 14. Angle command value) θv ^* [deg] is set. Since the operation of the valve opening command value setting unit 52 is the same as that of the valve opening command value setting unit 152 of FIG. 5, detailed description thereof is omitted.

The angle deviation calculation unit 53 is a deviation Δθv () between the valve opening command value θv ^* set by the valve opening command value setting unit 52 and the actual rotation angle θv of the valve driving motor 15 detected by the rotation angle sensor 33. = Θv ^* −θv) is calculated.
The angle deviation converter 54 converts the angle deviation Δθv calculated by the angle deviation calculator 53 into a control angle deviation Δθv ′ having a dead zone that becomes zero when the absolute value of the angle deviation Δθv is equal to or less than a predetermined value. FIG. 3 is a graph showing the relationship between the preset angle deviation Δθv and the control angle deviation Δθv ′. In a region where the absolute value of the angle deviation Δθv is equal to or smaller than a predetermined value A (A> 0), a dead zone where the control angle deviation Δθv ′ is zero is set. The predetermined value A is set to, for example, 0.05 [deg] in mechanical angle. In a region where the angle deviation Δθv is larger than A, the control angle deviation Δθv ′ takes a positive value and is set to increase as the angle deviation Δθv increases. In a region where the angle deviation Δθv is smaller than −A, the control angle deviation Δθv ′ takes a negative value, and is set to become smaller as the angle deviation Δθv becomes smaller.

The angle deviation converter 54 converts the angle deviation Δθv into the control angle deviation Δθv ′ based on the relationship between the preset angle deviation Δθv and the control angle deviation Δθv ′ as shown in FIG. To do. The angle deviation calculation unit 53 and the angle deviation conversion unit 54 constitute control angle deviation generation means for generating a control angle deviation Δθv ′ based on the rotation angle command value θv ^* and the actual rotation angle θv. .

The PID control unit 55 includes a proportional element 71, an integral element 72, a differential element 73, a first adder 74, and a second adder 75. Here, Kp is a proportional gain, Ki is an integral gain, 1 / Z is a transfer function of a delay element for outputting an input signal with a delay of one calculation cycle, Kd is a differential gain, and LPF is a low-pass filter.
In this embodiment, the proportional deviation 71 and the differential element 73 are directly given the angular deviation Δθv calculated by the angular deviation calculator 53. On the other hand, the integral element 72 is given the control angle deviation Δθv ′ calculated by the angle deviation converter 54.

The proportional element 71 calculates a proportional operation amount (proportional term; hereinafter referred to as “proportional operation amount”) by performing a proportional calculation on the angle deviation Δθv calculated by the angle deviation calculation unit 53. Specifically, the proportional element 71 calculates the proportional operation amount by multiplying the angular deviation Δθv by the proportional gain Kp.
The integral element 72 performs an integral operation on the control angle deviation Δθv ′ calculated by the angle deviation conversion unit 54 to thereby obtain an operation amount (integral term, hereinafter referred to as “integration operation amount”) of the integration operation. Calculate. Specifically, the integration element 72 adds the previous integration operation amount to the value obtained by multiplying the control angle deviation Δθv ′ calculated by the angle deviation conversion unit 54 by the integration gain Ki, thereby obtaining the current integration operation. Find the amount.

The proportional manipulated variable calculated by the proportional element 71 and the integral manipulated variable calculated by the integral element 72 are given to the first adder 74. The first adder 74 adds the proportional operation amount and the integral operation amount. The addition result of the first adder 74 is given to the second adder 75.
The differential element 73 calculates a differential operation amount (differential term; hereinafter referred to as “differential operation amount”) by performing a differential operation on the angle deviation Δθv calculated by the angle deviation calculation unit 53. Specifically, the differential element 73 includes a first LPF 73a, a subtractor 73b, a second LPF 73c, and a multiplier 73d. The first LPF 73 a extracts a low frequency component of the angle deviation Δθv calculated by the angle deviation calculation unit 53. The subtractor 73b removes the low frequency component extracted by the first LPF 73a from the angle deviation Δθv calculated by the angle deviation calculator 53. Thereby, the high frequency component of the angle deviation Δθv is extracted. That is, a differential value (angle deviation differential value) of the angle deviation Δθv is calculated. The second LPF 73c removes the high frequency component of the angular deviation differential value. The multiplier 73d calculates the differential manipulated variable by multiplying the angular deviation differential value after the high frequency component is removed by the differential gain Kd. The differential operation amount calculated by the differential element 73 is given to the second adder 75.

The second adder 75 adds the differential operation amount calculated by the differential element 73 to the addition result (proportional operation amount and integral operation amount and sum) of the first adder 74, thereby obtaining the current command value I ^* . Calculate.
The angle deviation calculation unit 53, the angle deviation conversion unit 54, and the PID control unit 55 constitute rotation angle feedback control means for guiding the actual rotation angle θv of the valve drive motor 15 to the valve opening command value θv ^*. Yes.

The current deviation calculation unit 56 calculates a deviation ΔI (= I ^* −I) between the current command value I ^* obtained by the PID control unit 55 and the motor current (actual current) I detected by the current sensor 36. . PI control unit 57 performs PI calculation on current deviation ΔI calculated by current deviation calculation unit 56. That is, the current deviation calculation unit 56 and the PI control unit 57 constitute current feedback control means for guiding the motor current flowing through the valve driving motor 15 to the current command value. The PI control unit 57 calculates the voltage command value V ^* [V] to be applied to the valve driving motor 15 by performing PI calculation on the current deviation.

The valve drive motor 15 is described as a motor model (1 / (L · s + R)) which is a mathematical model. It is considered that a deviation between the voltage command value V ^* [V] calculated by the PI controller 57 and the induced voltage E [V] is applied to the valve drive motor 15. As a result, the motor current I [I] flows through the valve driving motor 15. This motor current I is detected by the current sensor 36 and fed back to the current deviation calculator 56.

  A value obtained by multiplying the motor current I by the torque constant Kt [N · m / A] of the valve driving motor 15 is the motor torque [N · m]. A value obtained by subtracting the load torque TL [N · m] required for driving the hydraulic control valve 14 from the motor torque Tm is the torque Tv [N · m] applied to the hydraulic control valve 14. A value obtained by multiplying the torque Tv by 1 / (J · s) is the motor rotation speed ω [rad / s]. A value obtained by multiplying the motor rotation speed ω by the counter electromotive voltage constant Ke [V · s / rad] of the valve driving motor 15 is the induced voltage E [V].

Further, a value obtained by multiplying the motor rotation speed ω by 1 / s becomes the rotation angle of the valve driving motor 15. The rotation angle sensor 33 detects the actual rotation angle [deg] of the valve driving motor 15. The actual rotation angle detected by the rotation angle sensor 33 is fed back to the angle deviation calculation unit 103.
In this way, the valve drive motor 15 is feedback-controlled so that the opening degree θv of the hydraulic control valve 14 becomes equal to the valve opening degree command value θv ^* .

In the embodiment, the integration element 72 calculates the integral operation amount by performing the integral calculation on the control angle deviation Δθv ′ rather than performing the integral calculation on the angle deviation Δθv. The control angle deviation Δθv ′ has a dead zone that becomes zero when the absolute value of the angle deviation Δθv is equal to or smaller than a predetermined value A. Therefore, even if a small angle deviation Δθv occurs due to detection noise or the like of the actual rotation angle θv in the steering holding state, the control angle deviation Δθv ′ maintains a zero value, so that the absolute value of the integral operation amount is The increase can be suppressed or prevented. As a result, it is possible to suppress or prevent the current command value I ^* from fluctuating even when the rotor of the hydraulic control valve 14 is stationary due to friction in the steering holding state. Thereby, it can suppress that extra power consumption generate | occur | produces at the time of a steering maintenance state.

FIG. 4 is a graph showing temporal changes in the current command value and the like in the steering holding state in the valve drive motor control device 43 shown in FIG. Specifically, FIG. 4 shows the temporal change in the internal pressure P, the valve opening command value θv ^* , the actual rotation angle θv, the current command value I ^*, and the actual current I in the hydraulic control valve 14 in the steered state ( Measured value). However, since there are many portions where the current command value I ^* and the actual current I overlap with each other, FIG. 4 shows them without distinction. Similarly, there are many portions where the valve opening command value θv ^* and the actual rotation angle θv overlap each other, and in FIG. 4, they are drawn without distinction. From FIG. 4, it can be seen that in the valve drive motor control device 43 in the present embodiment, the fluctuation of the current command value I ^* during the steering holding state is small.

  As mentioned above, although embodiment of this invention was described, this invention can also be implemented with another form. For example, in the valve drive motor control unit 43 of FIG. 2, the integral element 72 calculates the integral operation amount by performing the integral calculation on the control angle deviation Δθv ′, whereas the proportional element 71 has the angle The proportional operation amount is calculated by performing a proportional calculation on the angle deviation Δθv calculated by the deviation calculating unit 53. Further, the differential element 73 calculates a differential operation amount by performing a differential calculation on the angle deviation Δθv calculated by the angle deviation calculation unit 53.

  However, the proportional element 71 may calculate a proportional operation amount by performing a proportional calculation on the control angle deviation Δθv ′. In this case, the proportional angle 71 is input with the control angle deviation Δθv ′ calculated by the angle deviation converter 54. Similarly, the differential element 73 may calculate the differential manipulated variable by performing differential calculation on the control angle deviation Δθv ′. In this case, the differential angle 73 is input with the control angle deviation Δθv ′ calculated by the angle deviation converter 54.

  In the above embodiment, the rotation angle feedback control means includes the PID control unit 55 for performing PID control. However, instead of the PID control unit 55, a PI control unit for performing PI control may be used. Good. In this case, the differential element 73 and the second adder 75 in the PID control unit 55 are omitted. Also in this case, as the integration element 72, an element for calculating the integral operation amount by performing the integral calculation on the control angle deviation Δθv ′ is used. The proportional element 71 may calculate a proportional operation amount by performing a proportional calculation on the angle deviation Δθv calculated by the angle deviation calculation unit 53 or may be proportional to the control angle deviation Δθv ′. A proportional operation amount may be calculated by performing a calculation.

  In addition, various design changes can be made within the scope of matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic type power steering apparatus, 2 ... Steering mechanism, 3 ... Steering wheel, 14 ... Hydraulic control valve, 15 ... Valve drive motor, 16 ... Power cylinder, 23 ... Hydraulic pump, 25 ... Pump drive motor, 33 ... Rotation angle sensor 36 ... Current sensor 51 ... Assist torque command value setting unit 52 ... Valve opening command value setting unit 53 ... Angle deviation calculation unit 54 ... Angle deviation change unit 55 ... PID (proportional integral derivative) Control unit 56 ... Current deviation calculation unit 57 ... PI (proportional integration) control unit 71 ... Proportional element 72 ... Integral element 73 ... Derivative element 74,75 ... Adder

Claims (5)

Hydraulic power that generates steering assist force by supplying hydraulic oil from a hydraulic pump to a power cylinder coupled to a steering mechanism of a vehicle via a hydraulic control valve that is not mechanically connected to a steering member. A steering device,
An electric motor for controlling the opening of the hydraulic control valve;
A rotation angle command value setting means for setting a rotation angle command value which is a target value of the rotation angle of the electric motor;
Rotation angle detecting means for detecting an actual rotation angle of the electric motor;
Feedback control means for feedback-controlling the electric motor so that the actual rotation angle detected by the rotation angle detection means is equal to the rotation angle command value set by the rotation angle command value setting means,
The feedback control means includes
Based on the rotation angle command value set by the rotation angle command value setting means and the actual rotation angle detected by the rotation angle detection means, the absolute value of the angle deviation between the rotation angle command value and the actual rotation angle. Control angle deviation generating means for generating a control angle deviation having a dead zone that becomes zero when A is less than or equal to a predetermined value A (A>0);
And a feedback element that calculates an operation amount based on the control angle deviation generated by the control angle deviation generation means. The control angle deviation generating means includes:
When the absolute value of the angle deviation between the rotation angle command value and the actual rotation angle is less than or equal to the predetermined value A, a control angle deviation that takes a zero value is generated, and when the angle deviation is greater than the predetermined value A A control angle deviation that takes a positive value and becomes larger as the angle deviation is larger is generated. When the angle deviation is smaller than −A, a negative value is taken and a smaller value is obtained as the angle deviation is smaller. The hydraulic power steering apparatus according to claim 1, wherein the hydraulic power steering apparatus is configured to generate an angular deviation for control.   3. The hydraulic system according to claim 1, wherein the feedback element is an integral element that calculates an integral operation amount by performing an integral operation on the control angle deviation generated by the control angle deviation generation unit. Power steering device.   The feedback control means includes PID control means including a proportional element, an integral element, and a derivative element, and at least an integral element of the proportional element, the integral element, and the derivative element term is based on the control angular deviation. The hydraulic power steering apparatus according to claim 1, wherein the hydraulic power steering apparatus is configured to calculate an operation amount.   The feedback control means includes PI control means including a proportional element and an integral element, and at least an integral element of the proportional element and the integral element calculates an operation amount based on the control angle deviation. The hydraulic power steering apparatus according to claim 1 or 2, wherein the hydraulic power steering apparatus is configured as described above.

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