JP3625420B2 - Steering angle detection mechanism and power steering device provided with steering angle detection mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering angle detection mechanism that detects a steering angle of a steering, and a power steering device that includes the steering angle detection mechanism.
[0002]
[Prior art]
As a conventional steering angle detection mechanism, JP-A-11-147480 is disclosed.GazetteIs known. The relative steering angle detection mechanism shown in FIG. 7 detects the steering angle relatively from the rotation angle of the steering shaft.
That is, a disk-shaped rotating plate 102 is fixed to the steering shaft 101. The rotating plate 102 is formed with steering angle detecting holes 103 at intervals of several degrees on concentric circles on the outer peripheral side. Further, a plurality of the steering angle detection holes 103 are formed at regular intervals over the entire circumference of the rotating plate 102.
A neutral position detecting hole 104 is formed inside the steering angle detecting hole 103, but only one is formed on the rotating plate 102.
[0003]
Further, a first steering angle sensor 105a and a second steering angle sensor 105b, which have a light emitting diode and a phototransistor opposed to each other with the rotating plate 102 therebetween and recognize the steering angle detection hole 103, and the neutral position detection. A neutral position sensor 106 for recognizing the hole 104 is provided. The first steering angle sensor 105 a and the second steering angle sensor 105 b are arranged at a pitch that is half the interval between the adjacent steering angle detection holes 103.
The rotating plate 102 rotates relative to the first steering angle sensor 105a, the second steering angle sensor 105b, and the neutral position sensor 106.
[0004]
The steering angle signals 107 a and 107 b from the first steering angle sensor 105 a and the second steering angle sensor 105 b are input to the CPU 109. The CPU 109 detects a relative steering angle from the initial position based on the phase difference between the steering angle signals 107a and 107b.
Further, the neutral position signal 108 from the neutral position sensor 106 is input to the CPU 109. When determining the neutral position, in addition to the neutral position signal 108, a vehicle speed signal from a vehicle speed sensor (not shown) is also input to the CPU 109. Further, the neutral position signal 108 is inputted to the CPU 109 when traveling at a certain vehicle speed or higher. In addition, when the neutral position signal 108 is continuously input for a predetermined time, it is determined that the position is the absolute neutral position.
Further, the absolute steering angle is determined from the absolute neutral position and the relative steering angle.
[0005]
[Problems to be solved by the invention]
In the steering angle detection mechanism that detects the relative steering angle, the neutral position sensor 106 detects the neutral position detection hole 104 not only when the steering angle is 0 degrees, but also from the position of 0 degrees. Sometimes it has been rotated. Because, when the steering wheel is rotated 360 degrees, the rotating plate 102 is also rotated 360 degrees, and the neutral positionFor detectionThis is because the hole 104 is also detected by the neutral position sensor 106.
like thisSteering angle detection mechanismFor example, the vehicle travels on a road having a constant angle curve such as an introduction road to a highway. Depending on the angle of this curve, the steering may be rotated 360 degrees. When the steering is rotated 360 degrees and the position is steered in this way, the conventional operating angle detection mechanism misidentifies the 360-degree position as an absolute neutral position.
[0006]
In order to prevent this misidentification, it is conceivable to increase the vehicle speed condition for detecting the neutral position. This is because it is almost impossible for the steering wheel of a car running at high speed to rotate 360 degrees.
But,As described aboveWhen the vehicle speed condition is set to high speed, the neutral position signal 108 is not input at low speed, and the absolute neutral position cannot be determined.
[0007]
An object of the present invention is to provide a steering angle detection mechanism that can correctly determine the absolute neutral position of the steering even at a low speed, and a power steering device including the steering angle detection mechanism.
[0008]
[Means for Solving the Problems]
The first invention is detected by a rotating plate that rotates integrally with the steering shaft, a neutral position signal unit that detects a neutral position on the rotating plate, a steering angle signal unit that detects a steering angle, and the neutral position signal unit. A neutral position detector for recognizing a neutral position signal, a steering angle detector for recognizing a steering angle signal detected by the steering angle signal, and the neutral position signal andSteering angleAnd a CPU for storing the signal. In the steering angle detection mechanism in which the rotating plate moves relative to the neutral position detection unit and the steering angle detection unit, the CPUNeutral position signalIs stored, and the combination of the neutral position signal and the steering angle with the highest detection frequency within a certain time is stored, and this is used as one set of data, and several sets of data are stored. The absolute neutral position is determined by summing up the values.
[0009]
The second invention totals several sets of data, determines an absolute neutral position, adds one set of data to the totaled data, adds the one set of data, and the total In the case where the data is different from the above data, it is characterized in that it is determined whether or not the absolute neutral position is updated.
[0010]
According to a third aspect of the present invention, a spool is incorporated in the main body, one end of the spool faces one pilot chamber that is always in communication with the pump port, and the other end of the spool faces the other pilot chamber with a spring interposed. An orifice is provided on the downstream side of the one pilot chamber, and pressure oil is guided to the steering valve that controls the power cylinder through the orifice, while the pressure on the upstream side of the orifice is used as the pilot pressure of the one pilot chamber. The downstream pressure is used as the pilot pressure of the other pilot chamber, and the movement position of the spool is controlled by the pressure balance between the two pilot chambers, and the pump discharge amount is guided to the steering valve side according to the movement position. The control flow rate QP and the return flow rate QT returned to the tank or pump are distributed and Fils is, of the solenoidExcitation currentThe variable orifice that controls the opening according to theExcitation currentA controller for controlling the steering angle is provided, and a steering angle detection mechanism is connected to the controller to calculate or store the steering angle θ and the steering angular velocity ω according to the steering angle from the steering angle detection mechanism. The solenoid current command value I1 corresponding to the steering angle θ and the solenoid current command value I2 corresponding to the steering angular velocity ω are stored or calculated, and the solenoid current command values I1 and I2 are added. Further, the solenoid current command value I7 for standby is added, and the variable orifice solenoid is added based on the total command value.Excitation currentThe steering angle detection mechanism includes a rotating plate that rotates integrally with the steering shaft, a neutral position signal unit that detects a neutral position on the rotating plate, a steering angle signal unit that detects a steering angle, and the neutral position. A neutral position detection unit for recognizing a neutral position signal detected by the signal unit; a steering angle detection unit for recognizing a steering angle signal detected by the steering angle signal unit; and the neutral position signal andSteering angleAnd a CPU for storing a signal, wherein the rotating plate moves relative to the neutral position detection unit and the steering angle detection unit. In the power steering apparatus, the steering angle detection mechanism includes a neutral position signal and the CPU.Neutral position signalIs stored, and a combination of the most frequent neutral position signal and steering angle within a certain time is stored, and this is used as one set of data, and several sets of data are stored. The absolute neutral position is determined by counting, and the controller does not output the solenoid current command value I1 until the absolute neutral position is determined.
According to a fourth aspect of the invention, the controller is configured such that the solenoid current command value for standby before the absolute neutral position is determined is larger than the solenoid current command value after the absolute neutral position is determined. And
[0011]
DETAILED DESCRIPTION OF THE INVENTION
1 to 7 show a first embodiment of the present invention. In the first embodiment, the neutral position detection hole 104 is used as a neutral position signal section, the steering angle detection hole 103 is used as a steering angle signal section, the neutral position sensor 106 is used as a neutral position detection section, and the steering angle detection section is used as a steering angle detection section. The first steering angle sensor 105a and the second steering angle sensor 105b are used.
The steering angle detection mechanism of this embodiment inputs a neutral position signal 108 to the CPU 109. This neutral position signal 108 is input when the vehicle speed from a vehicle speed sensor (not shown) is about 15 km / h or more. Yes.
[0012]
In this embodiment, the input neutral position signal 108 is identified and stored by the steering angle at this time. The absolute neutral position is determined based on the input frequency of the identified neutral position signal 108.
Other than this feature, it is the same as the conventional example. Therefore, the same components as those of the conventional example will be described using the same reference numerals as those of the conventional example.
[0013]
Further, FIG. 2 is a conceptual diagram showing the rotation trajectory of the steering and the detection point of the neutral position. As shown in FIG. 2, the steering wheel is used so as to rotate about one and a half times to the left and right from the absolute neutral position of the steering wheel. Further, the neutral position sensor 106 recognizes the neutral position detection hole 104 at a point indicated by an arrow in the figure.
The neutral position detected at the point indicated by the arrow is a point B when the steering rotation angle is 0 degree, a point A when the steering wheel is rotated 360 degrees to the right, and a point C when the steering wheel is rotated 360 degrees to the left. There are three points. Thus, there are three neutral positions to be detected, but the absolute neutral position is at point B.
A method for determining this point B as an absolute neutral position will be described below.
[0014]
In this embodiment, the neutral position based on the neutral position signal 108 is identified based on the relationship with the steering angle at that time. That is, as described above, the neutral position signal 108 is detected at three points, that is, when the steering angle is 0 degree and when the steering angle is rotated 360 degrees to the left and right.
Here, neutral position detectionStart withThe neutral position signal 108 input first is stored in the CPU 109 as a signal at the point x.
Then, the CPU 109 stores a neutral position signal 108 input at a position different from the x point, for example, when rotated 360 degrees to the right, as a signal at the y point. Further, a neutral position signal 108 that is input when a position different from the x and y points, for example, 360 degrees from the y point is further rotated is stored as the z point.
[0015]
The CPU 109 determines the absolute neutral position from the neutral position signal 108 and the point input thereto, and the control method will be described with reference to the flowchart of FIG.
When the control is started, the neutral position signal 108 and its point are monitored for 30 seconds in step S1. In step S2, it is determined at which point the frequency of the neutral position signal 108 is the highest in the 30 seconds, and the data of the point having the highest frequency is stored. This data is called point data. In addition, the above-described step S1 and step S2 are set as one set. That is, a portion surrounded by a dotted line in FIG. 3 is one set.
For example, when the x point signal is input three times, the y point signal is seven times, and the z point signal is input four times to the CPU 109 in step S1, the highest frequency point data is stored as the y point in step S2. .
[0016]
When the point data having the highest frequency of the one set is determined, it is determined in step S3 whether there are three sets or more of the highest frequency point data. When the point data is less than 3 sets, the process returns to step S1. On the other hand, when there are three or more sets of point data, the process proceeds to step S4.
In this step S4, the point data determined in each set are compared. In step S5, it is determined whether or not there are two or more identical spot data in the three sets of spot data. That is, if the point data having the highest frequency in the first set is the y point, the second set is the x point, and the third set is the y point, there are two y points. Therefore, it is determined in step S5 that there are two or more identical spot data, and the process proceeds to step S6. When there are not two or more identical point data, that is, when all three sets of point data indicate different points, the process returns to step S1.
[0017]
When it is determined in step S5 that there are two or more pieces of the same spot data, the spot indicated by the spot data is determined to be an absolute neutral position in step S6. That is, here, since there are two pieces of point data indicating the y point, the y point is determined to be an absolute neutral position.
As described above, in this embodiment, among the three neutral position detection points, the x point, the y point, and the z point, the point with the highest detection frequency is determined as the absolute neutral position.
[0018]
Further, in this embodiment, even after the absolute neutral position is determined from the three sets of data, a point indicating the neutral position is detected and the frequency is stored. Then, the determined absolute neutral position can be updated by comparing one set of data with past data.
The method for updating the absolute neutral position will be described with reference to the flowchart shown in FIG.
[0019]
When the absolute neutral position is determined in FIG. 3, the process proceeds to the flowchart of FIG. In step S11, it is determined whether or not four sets or more of point data have been input to the CPU 109.
When there are four sets or more of this data, the oldest point data is erased in step S12, and the process proceeds to step S13. On the other hand, when the point data is less than 4 sets in step S11, the process proceeds to step S13 as it is.
In this step S13 and the next step, step S14, a new set of point data is detected.
That is, in step S13, the neutral position signal 108 is monitored for 30 seconds, and the point where the neutral position signal 108 is input is stored. In step S14, it is determined which point has the highest frequency, and this is stored as point data.
[0020]
When new point data is detected in this way, in step S15, it is determined whether or not this point data matches the point data adopted when the previous absolute neutral position was determined. That is, since the point data adopted when the absolute neutral position was determined last time is the y point, it is determined whether the new point data is the same as the y point.
If it is determined that they match, the process proceeds to step S18, and the absolute neutral position is not updated. That is, when the new point data also indicates the y point, the absolute neutral position is determined as the same y point as the previous time.
[0021]
On the other hand, when it is determined in step S15 that the new spot data is different from the spot data adopted for determining the previous absolute neutral position, step S15 is executed.16Proceed to
This step S16Then, it is determined whether or not there is the same data as the new point data in the stored point data for the past two sets. When there is the same point data, step S17The new absolute position data is used to update the previous absolute neutral position.
[0022]
That is, the point data employed to determine the previous absolute neutral position is the y point, which is the y point in the first set, the x point in the second set, and the y point in the third set. However, it is assumed that the new set of point data is point x. In this case, since there are the same point data as the new point data x point in the past two sets, this point data x point is adopted to determine the absolute neutral position.
[0023]
Also, the above step S16When it is determined that there is no data that is the same as the new point data in the past two sets of point data,In step 18Delete this new point data. Then, the previous absolute neutral position is adopted without updating the previously determined absolute neutral position.
[0024]
In this embodiment, the control shown in FIG. 4 is repeated. Therefore, the absolute neutral position can be determined by always comparing the new point data and the old point data. Even if it is biased to left or right steering at the initial stage of traveling and the absolute neutral position is erroneously determined, it can be updated by repeating the subsequent control. Therefore, the longer the travel time, the lower the possibility that the absolute neutral position will be mistaken.
Further, according to the above method, the neutral position signal 108 is input at a vehicle speed of about 15 km / h or higher, so that it is natural that the vehicle is traveling at high speed, and the absolute neutral position is set even at low speed. Can be detected.
[0025]
Next, a power steering apparatus equipped with the steering angle detection mechanism shown in FIGS. 5 and 6 will be described as an example of an embodiment.
First, the overall configuration of the power steering apparatus will be described with reference to FIG. In the main body H,Flow control valve FA pump P is also integrated with the spool 1.
The spool 1 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 through the pump port 4. A spring 5 is interposed in the other pilot chamber 3. The pilot chambers 2 and 3 thus constructed are connected to the solenoid SOL.Excitation currentIt communicates with each other through a variable orifice a that controls the opening according to the above.
[0026]
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. 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, both the pilot chambers 2 and 3 communicate with each other via the variable orifice a, and the pressure on the upstream side of the variable orifice a is applied to one pilot chamber.2The downstream pressure acts on the other pilot chamber 3.
[0027]
The spool 1 has an acting force of one pilot chamber 2 and an acting force of the other pilot chamber 3.And the acting force of the spring 5Keeps a balanced position, but in that balanced position,Tank port 11Is determined.
Now, if the pump drive source 12 which consists of an engine etc. has stopped, pressure oil will not be supplied to the pump port 4. FIG. If no pressure oil is supplied to the pump port 4, no pressure is generated in the pilot chambers 2 and 3, so that the spool 1 maintains the illustrated normal position by the action of the spring 5.
[0028]
When the pump P is driven from the above state and pressure oil is supplied to the pump port 4, a flow can be made to the variable orifice a.Differential pressureWill occur. thisDifferential pressureAs a result, 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 to maintain the balance position.
As the spool 1 moves against the spring 5 in this way, the opening degree of the tank port 11 is increased, but the control flow rate guided to the steering valve 9 side according to the opening degree of the tank port 11 at this time A distribution ratio between QP and the return flow rate 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 degree of the tank port 11.
[0029]
The fact that the control flow rate QP is controlled according to the opening degree 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 finally determined according to the opening degree of the variable orifice a. become. This is because the movement position of the spool 1 is determined by the pressure difference between the pilot chambers 2 and 3, and the opening of the variable orifice a determines this pressure difference.
[0030]
Therefore, in order to control the control flow rate QP according to the vehicle speed and the steering situation, it is only necessary to control the opening of the variable orifice a, that is, the excitation current of the solenoid SOL.
This is because the opening of the variable orifice a is kept to a minimum when the solenoid SOL is in a non-excited state, and the opening is increased as the exciting current is increased.
[0031]
The steering valve 9 controls the supply flow rate to the power cylinder 8 in accordance with an 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 supply flow rate is decreased accordingly. The switching amount of the steering torque and the steering valve 9 is determined by a torsional reaction force such as a torsion bar (not shown).
[0032]
If the switching amount of the steering valve 9 is increased when the steering torque is large as described above, the assist force by the power cylinder 8 is increased accordingly. On the contrary, if the switching amount of the steering valve 9 is reduced, the assist force is reduced.
And the necessary (request) flow rate QM of the power cylinder 8 determined by the steering torque,Flow control valve FThe energy loss on the pump P side can be kept low by always making the control flow rate QP determined in (1) equal. This is because the energy loss on the pump P side is caused by the control flow rate QP and the power cylinder 8.Required flow rateThis is because it occurs due to a difference from QM.
[0033]
As described above, the control flow rate QP is set to the power cylinder 8.Required flow rateIn order to make it as close as possible to QM, the opening of the variable orifice a is controlled by the excitation current for the solenoid SOL, and the controller c controls this excitation current. A steering angle detection mechanism 16 is connected to the controller c, and a steering angle signal detected by the steering angle detection mechanism 16 is output to the controller c. Further, a vehicle speed sensor 17 is connected to the controller c so that a vehicle speed signal is input. Based on these two output signals, the excitation current of the solenoid SOL is controlled.
[0034]
In the figure, reference numeral 18 is a slit formed at the tip of the spool 1, and even when the spool 1 is at the position shown in the figure, one pilot chamber 2 always communicates with the flow path 7 via this slit 18. I am doing so. In other words, even when the spool 1 is in the illustrated state and the flow path 6 is closed, the oil discharged from the pump P is supplied to the steering valve 9 side through the slit 18. ing. Although the flow rate is very small as described above, the pressure oil is supplied to the steering valve 9 side for the purpose of preventing seizure of the entire apparatus, preventing disturbance such as kickback, and ensuring responsiveness. Because. However, these purposes are for the standby flow rate described later.QSThis can also be achieved by ensuring, so a detailed description will be given later.
[0035]
Reference numeral 19 denotes a driver connected between the controller c and the solenoid SOL.Reference numerals 13 and 14 are orifices provided in the flow path 10, and reference numeral 15 is a relief valve.
[0036]
The control system of the controller c is as shown in FIG. That is, the steering angle signal and the absolute neutral position signal from the steering angle detection mechanism 16 and the vehicle speed signal from the vehicle speed sensor 17 are input to the controller c. Then, the controller c calculates the steering angle θ and the steering angular velocity ω from the steering angle signal.
Based on these steering angle θ and steering angular velocity ω,Required flow rateQM is estimated, but in actuality, based on the steering torque,Required flow rateIt is more accurate to specify the QMInCan be controlled. However, if it is attempted to control the opening of the variable orifice a by detecting the steering torque, the current power steering system must be significantly changed.
[0037]
However, as in this embodiment, based on the steering angle θ and the steering angular velocity ω,Required flow rateIf QM is estimated, the current power steering system itself may be hardly changed.
For the above reason, the controller c determines the steering angle θ and the steering angular velocity ω.Based onThus, the excitation current of the solenoid SOL is controlled. The control mode is as shown in FIG.
The steering angle θ and the solenoid current command value I1 in FIG. 6 are determined based on a theoretical value at which the relationship between the steering angle θ and the control flow rate QP becomes a linear characteristic. Further, the relationship between the steering angular velocity ω and the solenoid current command value I2 is also determined based on a theoretical value in which the steering angular velocity ω and the control flow rate QP are linear characteristics.
[0038]
However, if the steering angle θ and the steering angular velocity ω do not become a certain set value or more, both of the command values I1 and I2 are output as zero. That is, when the steering wheel is neutral or in the vicinity thereof, the command values I1 and I2 are set to zero.
[0039]
The solenoid current command value I1 for the steering angle θ and the solenoid current command value I2 for the steering angular velocity ω may be stored in the controller c in advance as table values, or based on the steering angle θ or the steering angular velocity ω. In this case, the controller c may be operated each time.
[0040]
Further, the controller c outputs the steering angle current command value I3 and the steering angular velocity current command value I4 based on the output signal of the vehicle speed sensor 17, and these steering angle current command value I3 and The steering angular velocity current command value I4 may be stored in the controller c in advance as a table value, or may be calculated by the controller c each time based on the vehicle speed V.
[0041]
The steering angle current command value I3 is set to 1 in the low speed range and to 0.6, for example, in the maximum speed range. Further, the steering angular velocity current command value I4 is set to 1 in the low speed range, and for example, 0.8 in the maximum speed range.
That is, the steering angle current command value I3 is controlled in the range of 1 to 0.6, while the steering angular speed current command value I4 is controlled in the range of 1 to 0.8. Therefore, the gain from the low speed range to the maximum speed range is set to be larger for the steering angle current command value I3.
[0042]
The solenoid current command value I1 based on the steering angle θ is multiplied by the steering angle current command value I3 corresponding to the vehicle speed V. Therefore, the higher the vehicle speed V, the moreMultiplicationThe resulting output value, that is, the steering angle system current command value I5 becomes smaller. In addition, since the gain of the steering angle current command value I3 is larger than the gain of the steering angular velocity current command value I4, the reduction rate increases as the speed increases.
[0043]
On the other hand, for the solenoid current command value I2 based on the steering angular velocity ω, the steering angular velocity current command value I6 is output with the steering angular velocity current command value I4 corresponding to the vehicle speed as a limit value. The current command value I6 is also decreased according to the vehicle speed, but since the gain is smaller than the gain of the steering angular velocity current command value I4, the rate of decrease of the current command value I6 is the current It is smaller than the command value I5.
[0044]
The steering angle system current command value I5 output as described above is compared with the steering angular velocity system current command value I6.Current command valueI5 orCurrent command valueI6 is adopted.
However, the current command value I5 has a steering angle detection mechanism.16Therefore, the absolute neutral position is not input before the absolute neutral position is determined. Therefore, the current command value I6 is always employed before the absolute neutral position is determined.
[0045]
If the current command value I5 is output with inaccurate neutral position information before the absolute neutral position is determined, for example, a large command value may be output where the current command value must be zero. On the contrary, when a large current command value must be output, the command value zero is output.
Therefore, the steering angle detection mechanism16Until the absolute neutral position is determined, the current command value I5 is not output to ensure the safety and comfort of steering.
[0046]
Further, as described above, after the absolute neutral position is detected, the larger one of the current command values I5 and I6 is adopted, for the following reason. That is, during high speed traveling, the steering is rarely operated suddenly, and therefore, the steering angular velocity system current command value I6 is usually small, and the steering angular system current command value I5 is usually larger.
[0047]
Therefore, during high speed traveling, in order to increase the safety and stability of the steering operation, the gain of the current command value I5 of the steering angle system is increased while using the steering angle as a reference. In other words, the higher the traveling speed, the higher the ratio of decreasing the control flow rate QP, so that the energy loss is reduced.
[0048]
On the other hand, when the vehicle is traveling at a low speed, the steering is often suddenly operated. Therefore, in many cases, the steering angular velocity is larger. Thus, when the steering angular velocity is large, responsiveness is important.
Therefore, when the vehicle is traveling at low speed, the gain of the current command value I6 of the steering angular velocity system is reduced with reference to the steering angular velocity in order to improve the operability of the steering operation, that is, the responsiveness. In other words, even when the traveling speed is increased to some extent, when the steering is suddenly operated, the control flow rate QP is sufficiently secured to give priority to responsiveness.
[0049]
However, even if the traveling speed of the vehicle is constant, the steering angle system current command value I5 increases or the steering angular speed system current command value I6 increases. For example, when the steering is steered at a certain angle and the steering is stopped and held at the position of the steering angle θ, the steering angular velocity ω becomes zero. Therefore, even if the vehicle speed is the same, the current command value I6 for the steering angular velocity system is initially large, and the current command value I5 for the steering angular system becomes larger after entering the steering.
In any case, since the larger one of the current command values I5 and I6 is selected, any current command value is output under any traveling condition.
[0050]
If neither of the current command values I5 and I6 is output at the time of steering as described above, the control flow rate QP cannot be secured. If the control flow rate QP cannot be secured, the power cylinder 8 will move at the time of steering while losing the drag due to the self-aligning torque of the vehicle. If the power cylinder 8 moves without maintaining its position in this way, it is impossible to maintain the steering itself.
[0051]
However, as described above, since either one of the current command values I5 and I6 is used, neither of them becomes zero during the steering operation. In other words, since the steering angle θ is maintained even during steering, the solenoid current command value I1 can be secured. Therefore, the power required for steering can be maintained at the current command value I1.
[0052]
On the other hand, the steering may be suddenly operated even when traveling at high speed. At this time, since the current command value I6 of the steering angular velocity system is increased, the current command value I6 is selected. However, since the current command value I6 is a value controlled within the range of the limit value of the steering angular velocity current command value I4, safety is sufficiently ensured.
However, the minimum limit value of the steering angular velocity current command value I4 when the vehicle is traveling at a high speed is slightly larger than the minimum value of the steering angular current command value I3. That is, in this embodiment, as described above, the minimum value of the steering angle current command value I3 is set to 0.6, and the limit minimum value of the steering angular velocity current command value I4 is set to 0.8.
[0053]
Therefore, when the vehicle is traveling at high speed, the response is better when the control is performed with the current command value I6 of the steering angular velocity system than when the control is performed with the current command value I6 of the steering angular velocity system.
However, if the responsiveness is too good during high-speed driving, there is a risk that safety may be impaired. Therefore, the limit minimum value of the steering angular velocity current command value I4 is set to 0.8, and the basis thereof is based on safety based on the yaw rate of the vehicle.
[0054]
In other words, the yaw rate of the vehicle has a characteristic that the convergence is almost similar when traveling at a vehicle speed of about 60 km / h or less. That is, at 60 km / h or less, the convergence is almost the same regardless of whether the vehicle is traveling at 10 km / h or 40 km / h. Thus, the range in which the convergence of the yaw rate is stable is regarded as a safety limit, and the minimum limit value of the steering angular velocity current command value I4 is set to 0.8.
[0055]
Therefore, according to this embodiment, when the steering is suddenly operated while traveling at 100 km / h, the current command value I6 of the steering angular velocity system becomes large, and the current command value I6 is selected, 60 km / h The vehicle can be steered with the same safety and stability as when running on the road.
[0056]
Further, the standby current command value I7a or I7b is added to the current command value I5 or I6 selected as described above. the aboveStandby current command valueI7a is added after the absolute neutral position is determined by the steering angle detection mechanism,Standby current command valueI7b is added before the absolute neutral position is determined.
For this standbyCurrent command valueI7a and I7b are for always supplying a predetermined current to the solenoid SOL of the variable orifice a. Thus, the variable orifice a supplied with the standby current command values I7a and I7b has its opening degree even if the solenoid current command value based on the steering angle θ, the steering angular velocity ω, and the vehicle speed is zero. Maintain a constant and constant standby flow rateQSSecure.
[0057]
However, from the viewpoint of energy saving, the power cylinder 8 and steering valve 9 sideRequired flow rateIf QM is zero,Flow control valve FThe control flow rate QP is ideally zero, for the following reason. Setting the control flow rate QP to zero means returning the entire discharge amount of the pump P from the tank port 11 to the pump P or the tank T. And since the flow path which returns from the tank port 11 to the pump P or the tank T is in the main body H and is very short, there is almost no pressure loss. Since there is almost no pressure loss, the driving torque of the pump P can be suppressed to a minimum, which leads to energy saving.
From this meaning,Required flow rateFrom the viewpoint of energy saving, it is absolutely advantageous to set the control flow rate QP to zero when QM is zero.
[0058]
Nevertheless,Required flow rateThe standby flow rate QS is secured even when the QM is zero for the following three reasons.
(1) Prevention of burn-in of equipment
If a certain amount of oil is circulated through the equipment, the cooling effect of the oil can be expected.Standby flow QSWill fulfill this cooling function.
[0059]
(2) Resist to disturbances such as kickback and self-aligning torque
When a drag due to disturbance, self-aligning torque, or the like acts on the tire, it acts on the rod of the power cylinder 8. if,Standby flow QSIf this is not ensured, the tire will fluctuate due to the drag caused by this disturbance and self-aligning torque. But,Standby flow QSIf the above is secured, the tire will not wobble even if the above-mentioned drag acts. That is, the rod of the power cylinder 8 is engaged with a pinion or the like for switching the steering valve 9, so that when the drag acts, the steering valve9In the direction to counter the dragStandby flow QSWill be supplied. Therefore,Standby flow QSIf this is secured, it is possible to counter the disturbance caused by the kickback and the self-aligning torque.
[0060]
(3) Ensuring responsiveness
For example, if the standby flow rate QS is secured, the time to reach the target control flow rate QP can be shorter than when there is no standby flow rate QS. Since this time difference becomes responsiveness, the responsiveness can be improved by securing the standby flow rate QS.
[0061]
The standby flow rate QS is changed before and after the absolute neutral position is determined by the steering angle detection mechanism. That is, the current command value I7a is output before the absolute neutral position is determined, and the current command value I7b is output after the determination. The current command value I7a is set to a larger value than I7b.
[0062]
Thus, before and after the absolute neutral value is determined,For standbyThe reason why the current command value I7 is changed is as follows.
That is, as already described, the standby flow rate QS is a flow rate necessary for ensuring a constant flow rate even if the solenoid current command value based on the steering angle θ, the steering angular velocity ω, and the vehicle speed is zero. It is. However, before the absolute neutral position is determined, there is a possibility that the steering angle θ is not zero and is detected as a neutral position when it is 360 degrees. A steering angle θ of 360 degrees indicates that the steering wheel is rotated once to the left or right.
[0063]
When the vehicle is going to start from a state where the steering wheel is rotating once, it tries to return the steering wheel as close to the neutral position as possible. In such a case, even a littleStandby flow QSI want to ensure responsiveness by increasing.
Therefore, before the absolute neutral position is determined, the current command value I7a that is larger than the current command value I7b is output. Since a large current command value I7a is output, it can be returned immediately even when the steering wheel is rotating once.
And after the absolute neutral position is determined,Standby flow QSTherefore, the current command value I7a having a small value is output.
[0064]
Further, when the absolute neutral position is determined, if the current command value I7a is suddenly switched to I7b, the steering wheel may feel uncomfortable. In order to prevent this, even if the absolute neutral position is determined, the current command value I7a is not immediately switched to I7b.Standby current command valueSolenoid than I7aExcitation currentIs increased and then switched to the current command value I7b after returning to the neutral position again.
Therefore, the current command value I7a having a large value is not suddenly switched to the current command value I7b having a small value, and this switching is continuous. Since it is continuously switched, there is no sense of incongruity in steering.
[0065]
Next, the operation of this embodiment will be described.
Now, while the vehicle is traveling, the solenoid current command value I1 based on the steering angle and the steering angle current command value I3MultiplicationA steering angle system current command value I5, which is a value, is output. At the same time, a solenoid current command value I2 based on the steering angular velocity is output, and a current command value I6 for the steering angular velocity system is output with the current command value for fast steering angular velocity I4 as a limit value.
[0066]
Then, the magnitude of the current command value I5 for the steering angle system and the current command value I6 for the steering angular velocity system is determined, and the standby current command value I7 is added to the larger command value I5 or I6. When solenoidExcitation currentIs decided.
This solenoidExcitation currentWhen the vehicle is traveling at high speed, the current command value I5 of the steering angle system is mainly used as a reference, and when the vehicle is traveling at low speed, the current command value I6 of the steering angle speed system is mainly used as a reference.
[0067]
However, according to this embodiment, even when the vehicle is traveling at a low speed, when the steering is maintained, the solenoid current is set based on the current command value I5 of the steering angle system.Excitation currentIs decided.
Even when the vehicle is traveling at a high speed, when the steering is suddenly operated, the solenoid command is output based on the current command value I6 of the steering angular velocity system.Excitation currentIs decided. However, in this case, as described above, even when traveling at 100 km / h, the steering operation can be performed with the same safety and stability as when traveling at 60 km / h.
[0068]
According to this embodiment, energy can be saved by controlling the control flow rate QP using signals such as the steering angle, the steering angular velocity, or the vehicle speed. In addition, the absolute neutral position of the steering can be accurately determined even at low speeds, and an accurate steering angle can be detected by accurately determining the absolute neutral position. Therefore, the control flow rate QP can also be accurately controlled, and energy saving can be reliably achieved.
[0069]
【The invention's effect】
According to the first invention, the CPU includes a neutral position signal and theNeutral position signalThe steering angle at the time when is input is stored. Then, the combination of the neutral position signal and the steering angle that are most frequently within a certain time is stored, and this is used as one set of data, and the absolute neutral position is determined based on several sets of data. So this absolute neutralitypositionTherefore, it is not necessary to increase the vehicle speed in order to determine the accurate neutral position even at low speeds.
[0070]
According to the second invention, once the absolute neutral position is determined, the data adopted to determine the absolute neutral position is compared with a new set of data. It is determined whether to update the absolute neutral position. Therefore, the longer the travel time, the more accurate the absolute neutral position can be determined.
[0071]
According to the third aspect of the invention, since the solenoid current command value I1 is not output until the absolute neutral position is determined, the current command value is determined by an inaccurate neutral position before the absolute neutral position is determined. It will not be affected. Therefore, safety and comfort of steering are ensured even before the absolute neutral position is determined.
[0072]
According to the fourth aspect of the invention, the solenoid current command value for standby before the absolute neutral position is determined is made larger than the solenoid current command value after the absolute neutral position is determined. Even if this is mistaken before the position is determined, a quick steering operation is possible.
[Brief description of the drawings]
FIG. 1 is a schematic view of the present invention.
FIG. 2 is a conceptual diagram of the present invention.
FIG. 3 is a flowchart showing an embodiment of the present invention.
FIG. 4 is a flowchart showing an embodiment of the present invention.
FIG. 5 is a diagram showing an embodiment of the present invention.
FIG. 6 is a diagram showing an embodiment of the present invention.
FIG. 7 is a diagram showing a conventional example.
[Explanation of symbols]
101 Steering shaft
102 Rotating plate
103 Steering angle detection hole
104 Neutral position detection hole
105 Steering angle sensor
106 Neutral position sensor
107 Steering angle signal
108 Neutral position signal
109 CPU
110 Rotation signal
I Solenoid current command value
I1 Solenoid current command value by steering angle θ
I2 Solenoid current command value by steering angular velocity ω
I3 Steering angle current command value
I4For steering angular velocityCurrent command value
QP control flow rate
QT return flow rate
QM required flow rate (required flow rate)
QS standby flow
H      Body
1 spool
2 One pilot room
3 The other pilot room
4 Pump port
P pump
SOL solenoid
a Variable orifice
8 Power cylinder
9 Steering valve
ccontroller
16 Steering angle detection mechanism
17 Vehicle speed sensor

Claims (4)

A rotary plate that rotates integrally with the steering shaft, a neutral position signal unit that detects a neutral position on the rotary plate, a steering angle signal unit that detects a steering angle, and a neutral position signal detected by the neutral position signal unit are recognized. A neutral position detection unit, a steering angle detection unit for recognizing a steering angle signal detected by the steering angle signal unit, and a CPU for storing the neutral position signal and the steering angle signal are provided, and the rotating plate has the neutral position detection unit. In the steering angle detection mechanism that moves relative to the steering angle detection unit, the CPU stores the neutral position signal and the steering angle when the neutral signal is input, and has the highest detection frequency within a certain time. The absolute neutral position is determined by storing a combination of a high neutral position signal and a steering angle, and using this as one set of data and aggregating several sets of data. Steering angle detection mechanism was formed. When several sets of data are aggregated and the absolute neutral position is determined, and one set of data is added to the aggregated data, and the added one set of data differs from the aggregated data 2. The steering angle detection mechanism according to claim 1, wherein it is determined whether to update the absolute neutral position. A spool is incorporated in the main body, one end of this spool faces one pilot chamber that is always in communication with the pump port, and the other end of the spool faces the other pilot chamber with a spring interposed therebetween. An orifice is provided on the downstream side of the cylinder, and pressure oil is guided to the steering valve that controls the power cylinder through the orifice. The control position of the spool is controlled by the pilot pressure of the other pilot chamber, and the movement position of the spool is controlled by the pressure balance between the two pilot chambers, and the pump discharge amount to the steering valve side according to the movement position, and the tank Or the return flow rate QT to be returned to the pump and the orifice is With a variable orifice for controlling the opening in response to the exciting current of the maytansinoid, a controller for controlling the excitation current of the solenoid for the variable orifice provided, and, in the controller connects the steering angle detection mechanism, the steering angle While calculating or storing the steering angle θ and the steering angular velocity ω corresponding to the steering angle from the detection mechanism, the controller calculates the solenoid current command value I1 corresponding to the steering angle θ and the solenoid current command value I2 corresponding to the steering angular velocity ω. Is stored or calculated, and the solenoid current command values I1 and I2 are added, and the standby solenoid current command value I7 is added to the added value, and the solenoid of the variable orifice is based on the total command value. controls the exciting current, the steering angle detection mechanism rotates integrally with the steering shaft A rotating plate, a neutral position signal unit for detecting a neutral position on the rotating plate, a steering angle signal unit for detecting a steering angle, and a neutral position detecting unit for recognizing a neutral position signal detected by the neutral position signal unit; A steering angle detection unit for recognizing a steering angle signal detected by the steering angle signal unit, and a CPU for storing the neutral position signal and the steering angle signal are provided, and the rotating plate is provided in the neutral position detection unit and the steering angle detection unit. In the power steering device that moves relative to the steering angle detection mechanism, the steering angle detection mechanism stores a neutral position signal and a steering angle when the neutral position signal is input, and is the most frequent within a predetermined time. The combination of the neutral position signal and the steering angle is memorized, and this is used as one set of data. By summing up several sets of data, the absolute neutral position is determined. The controller power steering apparatus having a steering angle detection mechanism was configured not to output the solenoid current instruction value I1 to an absolute neutral position is determined. 4. The steering angle detection mechanism according to claim 3, wherein the controller is configured to make the standby solenoid current command value before the absolute neutral position is determined larger than the solenoid current command value after the absolute neutral position is determined. Power steering device with

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