JP2004149092A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optimum steering feeling by selecting control characteristics suited to respective drivers. <P>SOLUTION: A controller C comprises a table 20 for a steering angle for determining a solenoid current command value Iω from a steering angle signal θ; a table 21 for steering angular speed for determining the solenoid current command value Iω from a steering angular speed signal ω; and a table 22 for vehicle speed for determining a solenoid current command value Iv from a vehicle speed signal v. The table 20 for steering angle, the table 21 for steering angular speed, and the table 22 for vehicle speed include switching tables 20a to 20c, 21a to 21c, and 22a to 22c with different characteristics respectively. The controller C determines a solenoid current command value Iω on the basis of the switching tables 20a to 20c, determines the solenoid current command value Iω on the basis of the switching tables 21a to 21c, and determines the solenoid current command value Iv on the basis of the switching tables 22a to 22c. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power steering device provided with a flow control valve for controlling a flow guided to a power cylinder.
[0002]
[Prior art]
BACKGROUND ART As a conventional flow control device, for example, a device described in Patent Document 1 is known. FIG. 3 shows this conventional example.
As shown, a pump P is connected to the flow control valve V.
The spool 1 of the flow control valve V has one end facing one pilot chamber 2 and the other end facing the other pilot chamber 3. The one pilot chamber 2 is always in communication with the pump P via the pump port 4. A spring 5 is interposed in the other pilot chamber 3. The two pilot chambers 2 and 3 thus communicate with each other via a variable orifice a that controls the opening in accordance with the exciting current I of the solenoid SOL.
[0003]
That is, one pilot chamber 2 communicates with the inflow side of the steering valve 9 that controls the power cylinder 8 via the flow path 6 → the variable orifice a → the flow path 7. Further, the other pilot chamber 3 communicates with the inflow side of the steering valve 9 via the flow path 10 and the flow path 7.
Therefore, the two pilot chambers 2 and 3 communicate with each other through the variable orifice a, and the pressure on the upstream side of the variable orifice a acts on one pilot chamber 2 and the pressure on the downstream side of the variable orifice a changes to the other pilot chamber. 3 will work.
[0004]
Then, the spool 1 maintains a position where the acting force of the one pilot chamber 2 and the acting force of the other pilot chamber 3 and the acting force of the spring 5 are balanced. The degree is decided.
If the pump drive source 12 including the engine or the like is stopped, no pressure oil is supplied to the pump port 4. If no pressure oil is supplied to the pump port 4, no pressure is generated in both the pilot chambers 2 and 3, so that the spool 1 maintains the normal position shown in the figure by the action of the spring 5.
[0005]
When the pump P is driven from the above state and the pressure oil is supplied to the pump port 4, a flow is generated in the variable orifice a, and a differential pressure is generated there. Due to the action of the pressure difference, a pressure difference is generated between the pilot chambers 2 and 3, and the spool 1 moves against the spring 5 in accordance with the pressure difference, and maintains the above-mentioned balance position.
As described above, the opening of the tank port 11 is increased by the movement of the spool 1 against the spring 5, but the control flow rate guided to the steering valve 9 according to the opening of the tank port 11 at this time. The distribution ratio of QP and the return flow QT returned to the tank T or the pump P is determined. In other words, the control flow rate QP is determined according to the opening of the tank port 11.
[0006]
The fact that the control flow rate QP is controlled in accordance with the opening of the tank port 11 determined by the moving position of the spool 1 as described above means that the control flow rate QP is ultimately determined in accordance with the opening of the variable orifice a. become. This is because the moving position of the spool 1 is determined by the pressure difference between the pilot chambers 2 and 3, and the difference in pressure is determined by the opening of the variable orifice a.
[0007]
Therefore, in order to control the control flow rate QP according to the vehicle speed and the steering situation, the opening degree of the variable orifice a, that is, the exciting current of the solenoid SOL may be controlled.
This is because the opening of the variable orifice a can be arbitrarily controlled from the maximum to the minimum depending on the magnitude of the exciting current of the solenoid SOL.
[0008]
The steering valve 9 controls the pressure of the power cylinder 8 according to the input torque (steering torque) of a steering wheel (not shown). For example, if the steering torque is large, the supply amount to the power cylinder 8 is increased, and if the steering torque is small, the pressure of the power cylinder 8 is reduced accordingly. The steering torque and the switching amount of the steering valve 9 are determined by a torsional reaction force of a not-shown torsion bar or the like.
[0009]
If the switching amount of the steering valve 9 is increased when the steering torque is large as described above, the assisting force of the power cylinder 8 increases accordingly. Conversely, if the switching amount of the steering valve 9 is reduced, the assist force is reduced.
If the required (required) flow rate QM of the power cylinder 8 determined by the moving speed of the piston and the control flow rate QP determined by the flow control valve V are made as equal as possible, the energy loss on the pump P side can be suppressed low. This is because the energy loss on the pump P side is caused by the difference between the control flow rate QP and the required flow rate QM of the power cylinder 8.
[0010]
In order to make the control flow rate QP as close as possible to the required flow rate QM of the power cylinder 8 as described above, the opening degree of the variable orifice a is controlled by the solenoid current command value SI for the solenoid SOL. The controller C controls the SI.
The steering angle sensor 16 and the vehicle speed sensor 17 are connected to the controller C, and the exciting current of the solenoid SOL is controlled based on the output signals of both sensors. That is, the controller C includes a table for determining the solenoid current command value Iv based on the steering angle signal from the steering angle sensor 16, and includes a table for determining the solenoid current command value Iv based on the vehicle speed signal from the vehicle speed sensor 17. I have. The exciting current of the solenoid SOL is controlled based on these table values.
[0011]
In the drawing, reference numeral 18 denotes a slit formed at the tip of the spool 1 so that one pilot chamber 2 always communicates with the flow path 7 through the slit 18 even when the spool 1 is at the position shown in the figure. ing. In other words, even when the spool 1 is in the illustrated state and the flow path 6 is closed, the discharge oil of the pump P is supplied to the steering valve 9 side through the slit 18. ing.
[0012]
The reason why the pressure oil is supplied to the steering valve 9 side at a very small flow rate is to prevent disturbance such as kickback and to ensure responsiveness.
Reference numeral 19 denotes a driving device for the solenoid SOL connected between the controller C and the solenoid SOL.
Reference numerals 13 and 14 are throttles, and reference numeral 15 is a relief valve.
[0013]
[Patent Document 1]
JP 2001-260917 A (pages 3 to 6, FIG. 1)
[0014]
[Problems to be solved by the invention]
As described above, conventionally, when the solenoid current command value Iv is determined from the vehicle speed, or when the solenoid current command value Iθ is determined from the steering angle, the table provided in the controller C is used. However, each of the tables has only one type.
[0015]
Therefore, for example, when the characteristics of the table are determined according to a person having strong arm strength, the assisting force of the power cylinder becomes smaller. If the assist force is small and a person with weak arm operates it, the steering wheel may become too heavy.
Conversely, when the characteristics of the table are determined in accordance with a person having weak arm strength, the assisting force of the power cylinder becomes larger. When the assisting force is increased, when a person with strong arm operates the assisting force, a situation occurs in which the steering wheel is too light.
[0016]
In other words, with the above settings, the control characteristics are definitely determined uniquely, and there is a problem that the optimum steering feeling cannot always be realized for each driver.
An object of the present invention is to provide a power steering device capable of realizing an optimum steering feeling by selecting a control characteristic suitable for each driver.
[0017]
[Means for Solving the Problems]
A first invention provides a steering valve for controlling a power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, A flow control valve that distributes a flow supplied from a pump to a control flow that guides a steering valve according to the opening degree of the variable orifice and a return flow that recirculates to a tank or a pump, and a steering angle sensor that detects a steering angle. The controller includes a steering angle table that determines a solenoid current command value Iθ based on the steering angle, and the steering angle table includes a plurality of switching tables having different characteristics, and the controller according to a switching signal. The switching table can be selected.
[0018]
A second invention provides a steering valve for controlling a power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, A flow control valve for distributing a flow supplied from a pump to a control flow for guiding the steering valve according to the opening degree of the variable orifice and a return flow for recirculating the tank or the pump, and a steering angular velocity identification for detecting or calculating the steering angular velocity Means, the controller includes a steering angular velocity table for determining a solenoid current command value Iω based on the steering angular velocity, and the steering angular velocity table includes a plurality of switching tables having different characteristics, and a switching signal. That the above switching table can be selected according to And it features.
[0019]
A third invention provides a steering valve for controlling a power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, A flow control valve that distributes a flow supplied from a pump to a control flow guided to a steering valve according to an opening degree of the variable orifice and a return flow to be recirculated to a tank or a pump, and a vehicle speed sensor that detects a vehicle speed, The controller includes a vehicle speed table that determines a solenoid current command value Iv based on the vehicle speed, the vehicle speed table includes a plurality of switching tables having different characteristics, and selects the switching table according to a switching signal. It is made possible.
[0020]
A fourth invention provides a steering valve for controlling a power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, A flow control valve that distributes a flow supplied from a pump to a control flow guided to a steering valve according to the opening degree of the variable orifice and a return flow returned to a tank or a pump, and a torque sensor that detects torque, The controller includes a torque table for determining the solenoid current command value It based on the torque, the torque table includes a plurality of switching tables having different characteristics, and selects the switching table according to a switching signal. It is made possible.
[0021]
The fifth invention is based on the first and second inventions, and includes a vehicle speed sensor for detecting a vehicle speed, a controller including a vehicle speed table for determining a solenoid current command value Iv based on the vehicle speed, and The switching table is provided with a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal.
[0022]
The sixth invention is based on the first invention and includes a steering angular velocity specifying means for detecting or calculating a steering angular velocity, and the controller includes a steering angular velocity table for determining a solenoid current command value Iω based on the steering angular velocity. In addition, the steering angle table includes a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal.
[0023]
The seventh invention is based on the first invention, and includes a vehicle speed sensor for detecting a vehicle speed, and a steering angular speed specifying means for detecting or calculating a steering angular speed, and the controller is configured to control the solenoid current command value Iv based on the vehicle speed. , A plurality of switching tables having different characteristics, and a steering angular speed table for determining the solenoid current command value Iω based on the steering angular speed. A switching table for the vehicle speed and a switching table for the steering angular velocity can be selected according to a switching signal.
[0024]
The eighth invention is based on the fourth invention and includes a vehicle speed sensor for detecting a vehicle speed, the controller includes a vehicle speed table for determining a solenoid current command value Iv based on the vehicle speed, and the controller includes a vehicle speed table. Is provided with a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
The embodiment shown in FIGS. 1 and 2 has a feature in the controller C. Accordingly, hereinafter, the controller C will be described in detail, and the same reference numerals will be given to the same components as those in the related art, and the description thereof will be omitted.
[0026]
The controller C includes a steering angle table 20 for determining a solenoid current command value Iθ from the steering angle signal θ, a steering angular speed table 21 for determining a solenoid current command value Iω from the steering angular speed signal ω, and a vehicle speed signal v. A vehicle speed table 22 for determining the solenoid current command value Iv.
Further, the controller C has a switching unit 23 connected to each of the tables 20, 21, 22.
[0027]
The steering angle table 20 includes switching tables 20a, 20b, and 20c having different characteristics. The switching table for steering angle has, for example, characteristics as shown in FIGS. 2 (a), 2 (b) and 2 (c).
That is, in the switching table 20a shown in FIG. 2A, the solenoid current command value Iθ is set to be larger than the steering angle signal θ. In the switching table 20c shown in FIG. 2C, the output is made smaller. Then, in the switching table 20b shown in FIG. 2B, an intermediate portion between the switching tables 20a and 20c is output.
[0028]
The solenoid current command value Iθ determined by the steering angle table 20 is determined based on a theoretical value that makes the relationship between the steering angle signal θ and the control flow rate QP linear characteristics.
[0029]
The steering angular velocity table 21 also includes switching tables 21a, 21b, and 21c having different characteristics. The solenoid current command value Iω determined by the steering angular velocity table 21 is determined based on a theoretical value that makes the steering angular velocity signal ω and the control flow rate QP linear characteristics.
[0030]
The steering angular velocity signal ω input to the steering angular velocity table 21 is calculated by differentiating the steering angle signal θ from the steering angle sensor 16 using the steering angle sensor 16 as the steering angular velocity specifying means. . A steering angular velocity sensor may be separately provided as the steering angular velocity specifying means, and the steering angular velocity signal ω may be directly obtained from the steering angular velocity sensor.
[0031]
The table 22 for the vehicle speed also includes switching tables 22a, 22b, and 22c having different characteristics. The solenoid current command value Iv determined by the vehicle speed table 21 outputs 1 when the vehicle speed is low and outputs 0 when the vehicle speed is high. In the middle speed range between the low speed range and the high speed range, values below the decimal point from 1 to zero are output.
[0032]
Further, the controller C stores in advance a combination of the switching tables 20a to 20c, 21a to 21c, and 22a to 22c. For example, a combination with a switching table 22a for the vehicle speed is set as the A type according to a person having strong strength. In the case of the A type, control is performed so that the assisting force of the power cylinder is output to be relatively small.
In addition, a type in which a combination of switching tables is set according to a person having weak strength is a C type. In the case of the C type, control is performed so that the assisting force of the power cylinder is output to be relatively large. A type in which a combination for performing control between the A type and the C type is set is referred to as a B type.
[0033]
The above A to C types can be selected by a driver. Then, when the driver selects one of the above types, the selection signal is input to the switching unit 23 of the controller C. When a signal from the driver is input to the switching unit 23, the switching unit 23 selects each switching table set according to the signal. That is, any one of the set switching tables 20a to 20c for steering is selected. Similarly, one of the switching tables for steering angular velocity 21a to 21c and one of the switching tables for vehicle speed 22a to 22c are selected. Then, the following control is performed based on the selected switching table.
[0034]
First, the controller C determines the solenoid current command value Iθ based on the tables 20a to 20c selected from the steering angle signal θ, and determines the solenoid current command value Iω based on the tables 21a to 21c selected from the steering angular speed signal ω. decide. If the steering angle signal θ and the steering angular velocity signal ω do not exceed a certain set value, the solenoid current command value Iθ and the solenoid current command value Iω output zero. That is, when the steering wheel is at or near neutral, both the solenoid current command values Iθ and Iω are set to zero.
After the solenoid current command value Iθ and the solenoid current command value Iω are determined, both are added.
[0035]
When the two solenoid current command values Iθ and Iω are added as described above, the sum (Iθ + Iω) is multiplied by a solenoid current command value Iv based on the vehicle speed signal v.
The solenoid current command value Iv based on the vehicle speed signal v outputs 1 when the vehicle speed is low and outputs 0 when the vehicle speed is high. In the middle speed range between the low speed range and the high speed range, values below the decimal point from 1 to zero are output.
[0036]
Therefore, if the addition value (Iθ + Iω) is multiplied by the solenoid current command value Iv based on the vehicle speed signal v, (Iθ + Iω) is output as it is in a low speed region, and (Iθ + Iω) becomes zero in a high speed region.
In the medium speed range, a value that is inversely proportional to the speed increases as the speed increases.
Further, the standby solenoid current command value Is is added to (Iθ + Iω) × Iv. This is output from the controller C as a solenoid current command value I, and the solenoid excitation current is controlled based on the solenoid current command value I.
[0037]
The standby solenoid current command value Is is for ensuring that a predetermined current is constantly supplied to the solenoid SOL that controls the opening of the variable orifice a. That is, even when the solenoid current command values based on the steering angle signal θ, the steering angular speed signal ω, and the vehicle speed signal v are all zero, the variable orifice a maintains a constant opening degree by the standby solenoid current command value Is, and a predetermined standby The flow rate QS is always supplied to the steering valve 9 side.
[0038]
The reason for securing the constant standby flow rate QS in this way is as follows. That is, when a disturbance due to kickback or the like or a drag due to self-aligning torque or the like acts on the tire, it acts on the rod of the power cylinder 8. Even in such a case, the standby flow rate QS can be secured. This is because the tire can be prevented from wobbling. Further, if the standby flow rate QS is ensured, the responsiveness can be improved because the target control flow rate can be reached in a shorter time than when there is no standby flow rate QS.
In any case, the standby flow rate is always ensured, so that even when the vehicle is running straight in a low-speed range, disturbance due to kickback or the like can be countered, and good responsiveness during steering can be maintained.
[0039]
According to the above-described embodiment, if the driver selects a type that suits him / her, an optimal steering feeling according to that type can be realized.
In the above embodiment, the controller C includes the steering angle table 20, the steering angular velocity table 21, and the vehicle speed table 22, but may include a table for any one of the signals. In addition, various combinations are made, for example, the steering angle table 20 and the steering angular velocity table 21, the steering angular velocity table 21 and the vehicle speed table 22, and the steering angle table 20 and the vehicle speed table 22. It may be changed and used. However, in any case, a plurality of switching tables having different characteristics are provided.
Further, by inputting the plurality of signals to the controller C and providing a table corresponding to the signals, a variety of control can be provided, and the driver's steering feeling can be further improved.
Further, a torque sensor for detecting torque may be provided, a torque table may be provided, and the solenoid current command value may be determined based on the torque table. This torque table is also provided with a plurality of switching tables exhibiting different characteristics.
[0040]
Further, three types are prepared in advance in the controller C, and the driver selects the type that suits him / her from the three types. However, the driver may directly select the switching table. As described above, if the switching table is selected, the variation of the control is increased, and the steering feeling more suitable for the driver can be realized.
Further, as a means for the driver to select the type or the switching table, the driver may operate the controller C to select the type or the switching table. You may.
Further, in this embodiment, each table is provided with three types of switching tables. However, the number of switching tables is not limited to three as long as the table values can be changed.
[0041]
【The invention's effect】
According to the first to fourth aspects of the present invention, since the table for determining the solenoid current command value I includes a plurality of switching tables having different characteristics, a variety of control characteristics can be obtained. Therefore, control suitable for the driver can be realized.
[0042]
According to the fifth to ninth aspects, since a plurality of solenoid current command values for controlling the solenoid SOL are provided and a plurality of switching tables for determining each solenoid current command value are provided, the variation of control is further increased. Can be. Therefore, control suitable for the driver can be realized accordingly.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a control system of normal control of a controller according to a first embodiment.
FIG. 2A is a table showing a steering angle table 21a.
(B) This is a table showing the steering angle table 21b.
(C) This is a table showing the steering angle table 21c.
FIG. 3 is a circuit diagram of a conventional example.
[Explanation of symbols]
8 Power cylinder 9 Steering valve 17 Vehicle speed sensor 21 Steering angle table 22 Steering angular speed table 23 Vehicle speed table V Flow control valve P Pump a Variable orifice QP Control flow QT Return flow C Controller v Vehicle speed signal I Solenoid current command value

Claims (8)

A steering valve for controlling the power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, and a flow rate supplied from the pump. A flow control valve that distributes the control flow to the steering valve according to the opening degree of the variable orifice and the return flow to be recirculated to the tank or the pump, and a steering angle sensor that detects a steering angle. A steering angle table for determining the solenoid current command value Iθ based on the steering angle is provided, and the steering angle table includes a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal. A power steering device, characterized in that: A steering valve for controlling the power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, and a flow rate supplied from the pump. A flow control valve that distributes the control flow to the steering valve according to the opening degree of the variable orifice and the return flow to recirculate to the tank or the pump, and a steering angular velocity specifying means for detecting or calculating the steering angular velocity. The controller includes a steering angular velocity table that determines a solenoid current command value Iω based on the steering angular velocity, and the steering angular velocity table includes a plurality of switching tables having different characteristics, and the switching table according to a switching signal. Is a feature that makes it possible to select Steering apparatus. A steering valve for controlling the power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, and a flow rate supplied from the pump. A flow rate control valve that distributes a control flow rate guided to a steering valve in accordance with an opening degree of the variable orifice and a return flow rate recirculated to a tank or a pump, and a vehicle speed sensor that detects a vehicle speed. A vehicle speed table that determines the solenoid current command value Iv based on the vehicle speed. The vehicle speed table includes a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal. Power steering device. A steering valve for controlling the power cylinder, a variable orifice provided upstream of the steering valve, a solenoid for controlling the opening of the variable orifice, a controller for controlling the solenoid exciting current, and a flow rate supplied from the pump. A flow control valve that distributes the control flow to the steering valve according to the opening degree of the variable orifice and the return flow to recirculate the tank or pump, and a torque sensor that detects torque. And a torque table for determining a solenoid current command value It based on the torque table. The torque table includes a plurality of switching tables having different characteristics, and the switching table can be selected according to a switching signal. Power steering device. A vehicle speed sensor for detecting a vehicle speed; the controller includes a vehicle speed table for determining a solenoid current command value Iv based on the vehicle speed; the vehicle speed table includes a plurality of switching tables having different characteristics; 3. The power steering apparatus according to claim 1, wherein the switching table can be selected in accordance with the following. A controller for detecting or calculating a steering angular velocity; a controller having a table for steering angular velocity for determining a solenoid current command value Iω based on the steering angular velocity; 2. The power steering apparatus according to claim 1, further comprising a switching table, wherein the switching table can be selected according to a switching signal. A vehicle speed sensor for detecting a vehicle speed; and a steering angular speed specifying means for detecting or calculating a steering angular speed. The controller includes a vehicle speed table for determining a solenoid current command value Iv based on the vehicle speed. And a steering angular velocity table for determining the solenoid current command value Iω based on the steering angular velocity, and a plurality of switching tables having different characteristics, respectively. 2. The power steering apparatus according to claim 1, wherein a table and a switching table for steering angular velocity can be selected. A vehicle speed sensor for detecting a vehicle speed; the controller includes a vehicle speed table for determining a solenoid current command value Iv based on the vehicle speed; the vehicle speed table includes a plurality of switching tables having different characteristics; 5. The power steering apparatus according to claim 4, wherein the switching table can be selected according to the condition.

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