JP2008285042A - Vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle controller having a configuration for separating a steering wheel from a steering gear mechanically to stabilize its behavior when it is in a rack end position. <P>SOLUTION: A second controller 7 in this vehicle controller drives a current maintaining and reducing signal generating circuit 95 when the signal indicating the operation of an electromagnetic brake on a steering wheel side is inputted from an electromagnetic brake signal receiving means 102 at the time when a tire 4 reaches a rack end and supplies a maintaining current in such an extent that holds a state in which a rack gear of a steering rod 62 comes into contact with the rack end position into a steering motor 61 from a driving signal generating means 87. Even if an external force acts on the tire 4 by the supply of a maintaining current, a steering angle of the tire 4 is maintained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle control device.

  In a steer-by-wire vehicle control device in which a steering wheel and a steering gear that steers a steering wheel are mechanically separated, a sensor that detects rotation of the steering wheel is provided, and the steering angle of the steering wheel is detected by the sensor. The steering angle corresponding to this is calculated by the control device. Further, the steering gear is driven so that the steering wheel angle matches the steering angle.

Here, when the steering angle of the steering wheel is detected by a digital sensor such as a rotary encoder, the output of the sensor is reset when the ignition is turned on or off while the steering wheel is rotated by a predetermined angle. There is. Therefore, there is a conventional vehicle control device in which an analog sensor such as a potentiometer is further provided on the steering wheel to back up the steering angle information (see, for example, Patent Document 1). By monitoring the potentiometer output signal, the neutral position of the steering wheel can be detected, so if the digital sensor data is reset at the neutral position of the steering wheel, the steering angle of the steering wheel can be reliably detected. .
JP 2005-53334 A

However, when the difference between the steering angle and the steering angle is small, the current supplied to the steering motor is zero or a small value close to zero. When an external force is applied to the tire in this state, the steering angle may change due to the external force. In particular, when the steering motor current value is set to zero and power consumption is reduced when the rack end is reached, steering is performed when external force is applied while the steering angle is held at the rack end position. The angle was easy to change.
The present invention has been made in view of such circumstances, and has as its main object to stabilize the behavior when in the rack end position.

The invention according to claim 1 of the present invention that solves the above-described problems includes a steering shaft that is rotatably supported by a vehicle body of a vehicle, a steering wheel that is attached to the steering shaft and rotates together with the steering shaft, and a vehicle body. A steering wheel provided to be steerable, a steering motor that drives a rack and pinion mechanism of a steering rod that supports the steering wheel, an encoder that detects rotation of the steering motor, and the steering motor A current sensor for detecting a current supplied to the rack, and a rotation angle of the steering motor at a steering angle corresponding to a rack end, and the current supplied to the steering motor exceeds a predetermined value Rack end determination means for detecting the arrival at the rack end, and steering based on the determination result of the rack end determination means An electromagnetic brake means for applying a braking force to the wheel, and a signal indicating that the rack end determination means has reached the rack end while the brake means is operating the braking force, The vehicle control device is characterized by including a current maintaining circuit that makes a current supplied to the steering motor a sustaining current that can maintain a state in which the rack gear of the steering rod is in contact with the rack end position.
In this vehicle control device, a braking force is applied to the steering shaft at the rack end position, giving the driver a rack end feeling. At the same time, the steering motor is supplied with a current that does not easily change the steering angle of the steering wheel by an external force, so that the steering wheel does not shift from the rack end position. .

According to a second aspect of the present invention, in the vehicle control device according to the first aspect, the current maintaining circuit maximizes a current required for the steering wheel to be maintained as a maintaining current, and from this to 50% It is characterized by setting a current within the range.
In this vehicle control device, the current necessary and sufficient to maintain the steering angle of the steering wheel is maintained.

  According to the present invention, the current supplied to the steering motor at the rack end position can be suppressed, and the power consumption can be reduced. At the rack end position, current is supplied to the drive motor to such an extent that the steering angle of the steering wheel does not easily change with external force, so the steering angle of the steering wheel can be stably held at this position. Driving stability is further improved.

The best mode for carrying out the invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the vehicle control apparatus 1 operates a steering shaft 3 to which a steering wheel 2 as input means operated by a driver is attached, and a steered wheel (hereinafter referred to as a tire) 4. The steering gear 5 to be directed is not mechanically connected, and is electrically connected via the first control device 6 on the steering shaft 3 side and the second control device 7 of the steering gear 5.

The steering shaft 3 is rotatably supported by a housing 11 fixed to the vehicle body. The housing 11 accommodates a drive motor 12 and an electromagnetic brake means 15 in which a reduction mechanism is attached to an electric motor. The drive motor 12 and the electromagnetic brake means 15 are connected to the steering shaft 3 so as to be able to transmit power. Furthermore, a first encoder 13 that outputs a pulse signal according to the rotation of the steering wheel 2 and a second encoder 14 that detects a neutral point of the steering angle of the steering wheel 2 are attached to the housing 11. . The drive motor 12 is connected to the first control device 6 via the drive circuit 16. The electromagnetic brake means 15 generates a braking force that energizes the electromagnet to stop the rotation of the rotor, and is connected to the first controller 6 via the drive circuit 17. Each drive circuit 16, 17 has a switching element and the like, and is configured to supply current from a power source (not shown) to the drive motor 12 and the electromagnetic brake means 15.
Further, a torque sensor 18 is attached to the steering shaft 3. The torque sensor 18 is attached between the steering wheel 2 and the drive motor 12, and outputs a signal corresponding to the torque to the first control device 6.

  The first encoder 13 is an optical rotary encoder. The rotary encoder has a disk (not shown) that rotates together with the steering wheel 2, and two rows of patterns are formed on the disk. Each pattern is composed of, for example, slits having substantially the same width formed at equal intervals in the circumferential direction, and the arrangement of the slits in the other pattern is set to 1/4 of the slit width in the circumferential direction with respect to the arrangement of the slits in one pattern. It is arranged just shifted. Therefore, if the light emitting element and the light receiving element are arranged with the disc interposed therebetween, a signal in which the pulse generation timing is shifted by a quarter period corresponding to each pattern is obtained. An example of such a pulse signal is shown in FIG. Hereinafter, a first pulse signal generated by one pattern is referred to as an A-phase rotation detection signal Aw, and a second pulse train signal generated by the other pattern is referred to as a B-phase rotation detection signal Bw.

  The second encoder 14 is used as a center position detection sensor that detects a position at which the steering angle is reset. For example, a sensor is used that provides a marker on a disc that has been decelerated to rotate once when the steering wheel 2 is rotated within a steerable range, and that outputs a pulse signal when this marker is detected. The marker is provided corresponding to the rotational position of the steering wheel 2 when the tire 4 faces in the straight traveling direction. Since the vehicle is configured such that the tire 4 can be steered by the same amount on the right side and the left side with respect to the straight traveling direction, the rotational position of the steering wheel 2 at this time corresponds to a neutral point in the steerable region. To do. Accordingly, when the driver rotates the steering wheel 2, one neutral point position signal Cw (see FIG. 3) is output as the initial position signal each time the neutral point is reached. The neutral point position signal Cw is a pulse signal having a time width longer than ½ of each cycle of the rotation detection signals Aw and Bw and shorter than each cycle of the rotation detection signals Aw and Bw.

The first control device 6 includes, as first counting means, an up / down determination circuit 21 to which the rotation detection signals Aw and Bw are input, an edge detection circuit 22A to which the rotation detection signal Aw is input, and rotation detection. An edge detection circuit 22B to which the signal Bw is input and an up / down counter 24 as a first counter are included.
The up / down counter 24 is connected to the outputs of the edge detection circuits 22A and 22B via the OR circuit 25, and to the output of the up / down determination circuit 21 and the output of the reset signal shaping means 23. The reset signal shaping unit 23 generates a reset signal that resets the first count signal of the up / down counter 24 when the neutral point position signal Cw is input, and inputs the reset signal to the reset terminal.

The first count signal output from the up / down counter 24 is input to the steering angle calculation means 26. The steering angle calculation means 26 searches the steering angle map 27 and calculates the steering angle. The steering angle map 27 has a configuration in which the count value of the up / down counter 24 is associated with the steering angle. The steering angle calculation means 26 outputs a signal of an actual operation angle (actual steering angle) as a steering angle signal. The output is a steering angle signal output circuit 28, an angle difference signal calculation means 29, and a steering reaction force. The calculation means 30, the angle signal comparison means 31, and the rack end correspondence data storage means 32 are connected.
In addition to the actual steering angle, the angle difference signal calculating unit 29 receives a steering angle signal of the second control device 7 via the steering angle signal receiving unit 37. The calculation result of the angle difference of the actual steering angle with respect to the steering angle is input to the steering reaction force calculation unit 30 as an output of the angle difference signal calculation unit 29.
The steering reaction force calculation means 30 searches the steering reaction force map 38 and calculates the steering reaction force generated by the drive motor 12. The steering reaction force map 38 has a configuration in which an angle difference and a steering reaction force are associated with each other. The magnitude and direction of the steering reaction force are selected so that the steering angle matches the steering angle. The output of the steering reaction force calculation means 30 is connected to the drive signal generation means 39. The drive signal generation means 39 receives the steering reaction force signal calculated by the steering reaction force calculation means 30 and outputs a drive signal to the drive circuit 16.

The angle signal comparison means 31 compares the steering angle corresponding to the rack end position stored in the rack end correspondence data storage means 32 and the actual steering angle, and generates an electromagnetic brake signal when the angle difference between the two is equal to or less than a predetermined value. A signal is output to the means 44.
When the rack end corresponding data storage means 32 receives the rack end signal received by the rack end signal receiving means 40, it stores the actual steering angle at that time. The rack end signal is a signal generated by the second control device 7 and is generated when it is considered that the rack end position has been reached.
The electromagnetic brake signal generating means 44 is connected to the angle signal comparing means 31 and the rack end signal receiving means 40. The current value supplied to the electromagnetic brake means 15 by searching the map 45 with the angle difference signal by the input of the rack end signal. To decide. The output of the electromagnetic brake signal generating means 44 is connected to the drive circuit 17, the cutoff signal generating means 46 and the electromagnetic brake signal output circuit 48.
The cutoff signal generation means 46 outputs a cutoff signal to the drive signal generation means 39 in response to a signal input from the electromagnetic brake signal generation means 44. When the shut-off signal is output, the drive signal generation unit 39 stops generating the drive signal. When the release signal from the release signal generator 35 is input, the cutoff signal generator 46 stops the generation of the cutoff signal.

The release signal generation means 35 outputs a release signal to the electromagnetic brake signal generation means 44 and the cutoff signal generation means 46 in response to signal input from the reverse detection means 33 and the torque comparison means 47.
The reverse detection means 33 stores the determination result of the previous up / down determination circuit 21 in the memory 34, compares the previous determination result with the newly input determination result, and determines the reverse of the steering direction. After the determination, the newly input determination result is overwritten in the memory 34.

  The torque comparison means 47 receives the output of the torque sensor 18 via the torque detection means 49. When the torque value stored in advance in the memory 50 falls below, a signal is output to the release signal generating means 35 and the torque signal output circuit 51. The torque stored in advance in the memory 50 is the output of the torque sensor 18 a predetermined time ago.

  As shown in FIG. 2, the steering gear 5 includes a steering motor 61 in which a reduction mechanism is attached to an electric motor as driving means, and a rack and pinion mechanism that converts rotation of the steering motor 61 into linear motion of the steering rod 62. I have. The tire 4 is connected to both ends of the steering rod 62 via a tie rod 63 and a knuckle arm 64. The steering motor 61 is connected to the second control device 7 via the drive circuit 65. The drive circuit 65 includes a switching element and the like, and is configured to supply a current from a power source (not shown) to the steering motor 61.

The steering motor 61 is provided with a third encoder 66 that detects the steering angle from the rotation of the steering motor 61. The third encoder 66 uses an optical rotary encoder as described above. From the third encoder 66, an A-phase rotation detection signal Ag, which is a fourth pulse train signal, and a B-phase rotation detection signal Bg, which is a fifth pulse train signal whose pulse generation timing is shifted by ¼ cycle, Is output.
A fourth encoder 67 for detecting the neutral point of the steering angle is attached to the steering gear 5 as a center position detection sensor for detecting the position for resetting the steering angle. The fourth encoder 67 detects the neutral point of the steering angle by detecting the intermediate point between the rack end where the tie rod 63 moves to the right and the rack end where it moves to the left. A marking (not shown) that moves together with 63 is detected, and one neutral point position signal Cg (see FIG. 3) is output as an initial position signal. The neutral point position signal Cg is a pulse signal having a duration that is longer than ½ of each cycle of the rotation detection signals Ag and Bg and shorter than each cycle of the rotation detection signals Ag and Bg.

The second control device 7 includes, as second counting means, an up / down determination circuit 71 to which the rotation detection signals Ag and Bg are input, an edge detection means 72A to which the rotation detection signal Ag is input, and rotation detection. An edge detecting means 72B to which the signal Bg is inputted and an up / down counter 74 as a second counter are provided.
The up / down counter 74 is connected to the outputs of the edge detection means 72A and 72B via the OR circuit 75, and to the output of the up / down determination circuit 71 and the output of the reset signal shaping means 76. The reset signal shaping means 76 generates a reset signal for resetting the second count signal of the up / down counter 74 when the neutral point position signal Cg is inputted, and inputs the reset signal to the reset terminal. The output of the up / down counter 74 is connected to the steering angle calculation means 79.

The steering angle calculation means 79 searches the steering angle map 80 and calculates the steering angle. The steering angle map 80 has a configuration in which the count value of the up / down counter 74 is associated with the steering angle. The steering angle signal is transmitted to the first control device 6 through the steering angle signal output circuit 81 and output to the angle difference signal calculation means 82, the steering angle determination means 83, and the angle comparison means 84. Is done. The angle comparison unit 84 is configured to be able to refer to data registered in the memory 99. The memory 99 stores a steering angle before a predetermined time. The data in the memory 99 is rewritten as needed by the angle comparison means 84.
Further, the output of the steering angle calculation means 79 and the output of the OR circuit 75 are also connected to the rack end determination means 73.
The rack end determination unit 73 sends a signal to the rack end signal generation unit 97 when the count value of the timer 96 reaches a predetermined value. The rack end signal generating unit 97 generates a rack end signal and transmits the rack end signal from the operation state signal output circuit 98 to the first controller 6.

  A steering angle signal transmitted from the steering angle signal output circuit 28 of the first control device 6 is input to the angle difference signal calculation means 82 via the steering angle signal reception means 85. The output of the angle difference signal calculation means 82 is connected to the steering angle determination means 83. The steering angle determination means 83 searches the target steering angle map 86 and calculates the target steering angle. The target steering angle map 86 is set so that the output increases when the angle difference with respect to the actual steering angle is large. The target steering angle signal is converted into a drive signal by the drive signal generation means 87 and output to the drive circuit 65.

The current supplied from the drive circuit 65 to the steering motor 61 is monitored by the current sensor 91. The output of the current sensor 91 is input to the current comparison means 93 via the current detection circuit 92. The current comparison means 93 compares the current value detected by the current sensor 91 with the threshold value registered in the memory 94. When the current value exceeds the threshold value, a signal is output to the rack end determination means 73 and the current maintenance / reduction signal generation circuit 95. Further, an operation state signal is output from the operation state signal output circuit 98.
In addition to the current comparison means 93, the current maintenance / reduction signal generation circuit 95 is also connected to the output of the rack end signal generation means 97, the output of the angle comparison means 84, and the output of the stop signal generation means 100. Is output to the drive signal generation means 87 to reduce the current command value.
The stop signal generating means 100 is connected to a torque signal receiving means 101 and an electromagnetic brake signal receiving means 102. The torque signal receiving means 101 receives the torque comparison result transmitted from the first control device 6. The electromagnetic brake signal receiving unit 102 receives an operation signal of the electromagnetic brake unit 15 transmitted from the first control device 6.

Next, the operation of this embodiment will be described.
When the driver rotates the steering wheel 2, two pulse train signals (rotation detection signals Aw, Bw) are output to the first control device 6 according to the rotation angle from the first encoder 13. The up / down determination circuit 21 determines the rotation direction of the steering wheel 2 from the order in which the signal levels of the pulse train signals of the rotation detection signal Aw and the rotation detection signal Bw change. In the direction indicated by the arrow AA1 in FIG. 3, the rotation detection signal Bw becomes high level after the rotation detection signal Aw becomes high level. In this case, for example, it is assumed that the steering wheel 2 is steered rightward, and the up / down counter 24 is instructed to count up. When the steering wheel 2 is rotated in the reverse direction, each pulse is output in the direction opposite to the arrow AA1, that is, in the direction indicated by the arrow AA2. In this case, since the rotation detection signal Aw becomes high level after the rotation detection signal Bw becomes high level, the up / down determination circuit 21 instructs the up / down counter 24 to count down.

The edge detection circuit 22 </ b> A detects the rising edge and the falling edge of the rotation detection signal Aw pulse, and outputs them to the OR circuit 25. Similarly, the edge detection circuit 22B detects the rising edge and the falling edge of the rotation detection signal Bw pulse, and outputs them to the OR circuit 25. The OR circuit 25 calculates the logical sum of the signals from both edge detection circuits 22A and 22B, and creates a signal that causes a pulse to rise when one of the edge detection circuits 22A and 22B detects an edge. As a result, the resolution of the pulse signal output from the first encoder 13 is quadrupled.
The up / down counter 24 counts pulse signals output from the OR circuit 25 with reference to a neutral point position corresponding to straight traveling. When the up / down determination circuit 21 instructs to count up, the input pulse is added to the count value of the number of pulses up to the previous time. When the up / down determination circuit 21 instructs to count down, the input pulse is subtracted from the count value of the number of pulses up to the previous time.

  The steering angle calculation means 26 searches the steering angle map 27 with the first count signal output as the count value of the up / down counter 24, and acquires the actual steering angle corresponding to the first count signal. The actual steering angle signal (steering angle signal) is transmitted from the steering angle signal output circuit 28 to the second control device 7.

In the second control device 7, the steering angle signal is received by the steering angle signal receiving means 85. The angle difference signal calculation means 82 calculates a steering angle corresponding to the actual steering angle (hereinafter referred to as a target steering angle). Further, the difference between the current steering angle of the tire 4 calculated by the steering angle calculation means 79 (hereinafter referred to as the actual steering angle) and the target steering angle is calculated.
The steering angle determination means 83 searches the target steering angle map 86 with the angle difference to determine the target steering angle. The target steering angle is a steering angle at which the angle difference becomes zero. The drive signal generation means 87 creates a drive signal corresponding to the target steering angle and outputs it to the drive circuit 65, rotates the steering motor 61, and moves the steering rod 62. As a result, the angle of the tire 4 connected by the tie rod 63 or the like changes.

When the steering motor 61 rotates, two types of rotation detection signals Ag and Bg are output from the third encoder 66. The second control device 7 determines the rotation direction from the change in the signal level of each pulse train signal of each rotation detection signal Ag, Bg by the up / down determination circuit 71. The determination algorithm is the same as that of the up / down determination circuit 21 of the first control device 6. Further, the edge detection means 72A, 72B and the OR circuit 75 generate a pulse signal having a resolution four times that of the rotation detection signals Ag, Bg.
The up / down counter 74 counts up or down the pulse signal output from the OR circuit 75 in accordance with a command from the up / down determination circuit 71. The steering angle calculation means 79 searches the steering angle map 80 using the second count signal output as the count value of the up / down counter 74, and the steering angle calculation means 79 searches the steering angle map 80 using the count value. And determine the actual steering angle. The actual steering angle signal (steering angle signal) is input to the angle difference signal calculating means 82 and the steering angle determining means 83 and used for controlling the steering motor 61. Further, it is sent from the steering angle signal output circuit 81 to the first controller 6.

  In the first control device 6, the steering angle signal is received by the steering angle signal receiving unit 37, and the steering angle corresponding to the actual steering angle (hereinafter referred to as the target steering angle) is calculated by the angle difference signal calculating unit 29. To do. Further, the actual steering angle calculated by the steering angle calculation means 26 is acquired as a steering angle signal, and the angle difference between the target steering angle and the actual steering angle is calculated. The steering reaction force calculation means 30 searches the steering reaction force map 38 based on the angle difference signal obtained at this time, and the steering reaction force is determined. The drive signal generating means 39 generates a drive signal for the drive motor 12 according to the steering reaction force, and energizes the drive motor 12 from the drive circuit 16. A force is generated by the rotation of the drive motor 12 on the steering shaft 3 that is a rotating shaft connected to the drive motor 12. This force acts as a load for the driver who operates the steering wheel 2. As a result, the steering angle of the steering wheel 2 and the actual steering angle of the tire 4 quickly coincide with each other. In addition, information such as road surface conditions is transmitted to the driver, improving operability.

When the steering gear 5 moves to the rack end, the tire 4 cannot be steered any further. In this case, since the third encoder 66 attached to the steering motor 61 does not output a pulse signal, no pulse signal is output from the OR circuit 75 to the rack end determination means 73. At this time, if the driver further rotates the steering wheel 2 without noticing that it has reached the rack end, the steering angle of the tire 4 cannot be increased, so that the difference between the steering angle and the steering angle increases, and the steering motor The current supplied to 61 increases. When the detected value of the current sensor 91 exceeds the data registered in the memory 94, the current comparison means 93 outputs a signal to each of the rack end determination means 73 and the current maintenance / reduction signal generation circuit 95.
When the current maintaining / reducing signal generating circuit 95 receives a signal from the angle comparing means 84 in addition to the signal from the current comparing means 93, it outputs a current reducing signal to the drive signal generating means 87. The angle comparison means 84 outputs a signal when there is no difference between the steering angle registered in the memory 99 before a predetermined time and the current steering angle newly input. For this reason, the current maintaining / reducing signal generating circuit 95 determines that the steering operation is to be performed beyond the rack end when the current input to the steering motor 61 is large and the angle of the tire 4 does not change. Output a current reduction signal. Receiving this, the drive signal generation means 87 causes the drive circuit 65 to output a drive signal with a reduced current target value, and reduces the current input to the steering motor 61.

  The rack end determination unit 73 monitors the steering angle input from the steering angle calculation unit 79 and the outputs of the OR circuit 75 and the current comparison unit 93. When the steering angle is an angle corresponding to the rack end, and the pulse signal from the OR circuit 75 is not input and the signal from the current comparison means 93 is input, the timer 96 is started and a predetermined standby is performed. Wait until time has passed. When the standby time has elapsed, a signal is output to the rack end signal generating means 97, and a rack end signal notifying that the rack end has been reached is output from the rack end signal generating means 97. The rack end signal is transmitted from the operation state signal output circuit 98 to the first control device 6 and input to the operation state signal receiving means 41. Similarly, a current value signal is also transmitted from the operation state signal output circuit 98 of the second control device 7 to the first control device 6 and input to the rack end signal receiving means 40.

In the first control device 6, the rack end signal is input to the electromagnetic brake signal generating means 44 through the rack end signal receiving means 40. When the release signal is not generated, the electromagnetic brake signal generating means 44 creates a drive signal for the electromagnetic brake means 15 and controls the drive circuit 17 to operate the electromagnetic brake means 15. The braking force at this time is retrieved from the map 45 based on the result of the angle signal comparison means 31 calculating the difference between the actual steering angle and the steering angle corresponding to the rack end stored in the rack end correspondence data storage means 32. To be determined.
As a result, the electromagnetic brake means 15 generates a braking force on the steering shaft 3 to give the driver a rack end feeling. Further, the electromagnetic brake signal is also input to the cutoff signal generating means 46 of the electromagnetic brake means 15. The shut-off signal generator 46 outputs a shut-off signal to the drive signal generator 39. In response to this, the drive signal generating means 39 stops the output of the drive signal and stops the drive motor 12. As a result, instead of the steering reaction force of the drive motor 12, the braking force by the electromagnetic brake means 15 is applied to the steering shaft 3 to generate a rack end feeling.

  Accordingly, when the force applied to the steering wheel 2 by the driver is reduced, the output of the torque sensor 18 changes. The torque comparison means 47 compares the torque value with the data stored in the memory 50, and outputs a signal to the release signal generation means 35 if it falls below this value. A release signal is input to the electromagnetic brake signal generating means 44, and the braking by the electromagnetic brake means 15 is stopped. When the driver feels a rack end feeling, it is determined that the intention to stop further steering is performed with a decrease in torque, and this is reflected in the control of the electromagnetic brake means 15. Further, a release signal is input to the cutoff signal generating means 46. When the release signal is input, the cutoff signal generator 46 stops outputting the cutoff signal. The drive signal generating means 39 restarts the output of the drive signal and generates a steering reaction force by the drive motor 12. As a result, the steering reaction force of the drive motor 12 is applied to the steering shaft 3 instead of the braking force of the electromagnetic brake means 15.

  Further, when the steering wheel 2 is steered in the reverse direction, such an operation can be detected by the reverse detection means 33. The inversion detection means 33 compares the immediately preceding data stored in the memory 34 with the newly input data, and if both data are data indicating that the rotation direction is different, the inversion detection means 33 sends the data to the release signal generation means 35. Output a signal. A release signal is input to the electromagnetic brake signal generating means 44, and the braking by the electromagnetic brake means 15 is stopped. It is judged from the output of the first encoder 13 that the driver actually feels the end of the steering wheel 2 by feeling a rack end feeling, and control is performed to reflect this in the control of the electromagnetic brake means 15.

  While the electromagnetic brake signal generating means 44 operates the electromagnetic brake means 15, an electromagnetic brake signal indicating that the electromagnetic brake is applied is transmitted from the electromagnetic brake signal output circuit 48 to the second control device 7. Further, the torque comparison means 47 transmits the output of the torque sensor 18 to the second control device 7 through the torque signal output circuit 51 as a torque signal. These signals are used to control the steering motor 61 in a state where it hits the rack end.

The stop signal generating means 100 is used when the electromagnetic brake means 15 is operating, that is, when an electromagnetic brake signal is input from the electromagnetic brake signal receiving means 102, or while torque is being generated on the steering shaft 3, that is, when receiving the torque signal. While the signal is input from the means 101, the current maintenance / reduction signal generation circuit 95 outputs a maintenance signal, and the drive signal generation means 87 supplies a predetermined maintenance current. The maintenance current is a constant value that can maintain the state in which the rack gear of the steering rod 62 is in contact with the rack end position. The current value at this time is, for example, the maximum current required for the tire 4 to be stationary and within the range of 50% thereafter. That is, as shown in FIG. 4, a predetermined current value is supplied even at the rack end position. In addition, the line shown with a dotted line has shown the conventional electric current value. Conventionally, as the rack end position is approached, the current value decreases linearly and becomes zero at the rack end position.
When the signal from the torque sensor 18 input from the torque signal receiving means 101 is zero or inverted, the stop signal generating means 100 stops the current maintaining / reducing signal generating circuit 95. As a result, the drive signal generating means 87 zeroes or reverses the current supplied to the steering motor 61, and the tire 4 can be steered.

In this embodiment, when it is determined that the rack end has been reached on the steering gear 5 side, the driver can be given a rack end feeling using the electromagnetic brake means 15. During this time, since the drive motor 12 is stopped, current consumption can be reduced. By giving the driver a rack end feeling, the steering wheel 2 can be prevented from being rotated more than necessary, and the steering motor 61 can be prevented from being locked and flowing a large current.
The determination of the rack end arrival is made by monitoring the current input to the steering motor 61 and the steering angle, so that the current only increases during the steering, When the angle does not change, it is not determined that the rack end has been reached, and the accuracy of the determination process is improved. The rack end determination means 73 uses the timer 96 to generate a rack end signal when a predetermined time elapses in which it can be considered that the rack end has been reached, so that malfunction is prevented.

When it is determined that the rack end has been reached, the current supplied to the steering motor 61 is reduced by the current maintenance / reduction signal generation circuit 95, so that the steering motor 61 is locked and a large current flows. Can be prevented. Since the current reduction signal is output when the current value increases while the steering angle does not change, the actual steering angle with respect to the target steering angle or when the tire 4 is not being steered. Malfunctions can be prevented when the difference is only large.
Further, when the tire 4 is at the rack end position, the predetermined maintenance current is continuously supplied, so that the tire 4 becomes difficult to be steered by the drag from the road surface, and the stability is improved. For example, if the current required for the stationary operation of the tire 4 is maximized and within the range of 50% from this, the angle of the tire 4 does not fluctuate even when an external force is applied, and the rack end position can be maintained.

  Note that the present invention can be widely applied without being limited to the above-described embodiment.

It is a block diagram which shows the structure by the side of the steering wheel of the control apparatus for vehicles which concerns on embodiment of this invention. It is a block diagram which shows the structure by the side of the steering gear of the control apparatus for vehicles. It is a figure explaining the signal input into an up / down counter. It is a figure which shows typically the relationship between the electric current supplied to a drive motor, and a steering angle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus for vehicles 2 Steering wheel 3 Steering shaft 4 Tire (steering wheel)
DESCRIPTION OF SYMBOLS 5 Steering gear 15 Electromagnetic brake means 44 Electromagnetic brake signal generation means 61 Steering motor 62 Steering rod 66 Third encoder 91 Current sensor 95 Current maintenance / reduction signal generation circuit

Claims (2)

A steering shaft rotatably supported on the vehicle body;
A steering wheel attached to the steering shaft and rotating together with the steering shaft;
A steering wheel provided on the vehicle body to be steerable;
A steering motor that drives a rack and pinion mechanism of a steering rod that supports the steering wheel;
An encoder for detecting rotation of the steering motor;
A current sensor for detecting a current supplied to the steering motor;
Rack end determination that detects that the steering end has been reached when the steering motor rotation is not detected at the steering angle corresponding to the rack end and the current supplied to the steering motor exceeds a predetermined value. Means,
Electromagnetic brake means for applying a braking force to the steering wheel in response to the determination result of the rack end determination means;
While the brake means is applying a braking force and while the rack end determination means is outputting a signal indicating that the rack end has been reached, the current supplied to the steering motor is supplied to the steering rod. A vehicle control device comprising: a current maintaining circuit configured to maintain a current sufficient to maintain a state in which the rack gear is in contact with the rack end position.   2. The vehicular vehicle according to claim 1, wherein the current maintaining circuit maximizes a current required for turning off the steering wheel as a maintaining current, and sets a current within a range of 50% thereafter. Control device.

Images