JP2006347399A - Camber angle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a camber angle control device which can appropriately use a canvas last applied to a wheel provided with a camber angle as a cornering force and achieve both improvement in stability during turning and good steering feeling. .
A vehicle body 2 is suspended and supported via an upper arm 3 and a lower arm 4, and an actuator 6 for increasing or decreasing a camber angle of a steering wheel 1 connected to a steering mechanism via a tie rod 16 is provided. It is set as the structure operated according to the operation command from the camber angle control part 7. The camber angle control unit 7 is configured to predict and calculate a cornering force and a canvas last applied to the wheel 1 during turning, and to control the actuator 6 so as to obtain a camber angle that maximizes the sum thereof.
[Selection] Figure 1

Description

  The present invention relates to a camber angle control device that operates to increase / decrease a camber angle of a steering wheel during turning of a vehicle.

  When a wheel that supports the body of an automobile on the road surface is viewed from the front, the angle formed with respect to the vertical line of the road surface is referred to as a camber angle, and when this camber angle occurs, the lateral force in the direction inclined to the wheel (Canvas last) is added, and there is a problem in that it affects stability during straight traveling and turning. The straight running stability can be improved by attaching the wheel to the vehicle body so that the camber angle becomes zero, but when turning, the camber angle changes according to the roll of the vehicle body due to centrifugal force. Therefore, in many vehicles, the left and right wheels are attached with a slight outward inclination (positive camber), so as to achieve both stability during straight traveling and turning.

  However, there is a limit to the optimization of the camber angle by attaching the wheel as described above, and in some vehicles, the steering wheel that suspends the vehicle body by a pair of upper and lower upper arms and a plurality of lower arms is targeted. The camber angle of the wheel is increased / decreased during turning, thereby improving the turning performance (for example, see Patent Document 1).

In this device, a tie rod that pushes and pulls a steering wheel for steering is connected to a pivot portion on the vehicle body side of an upper arm that suspends and supports the upper portion of the wheel, and the camber angle of the wheel is adjusted according to the movement of the tie rod. Mechanically increasing / decreasing, a negative camber is given to the wheel outside the turning circle, and a positive camber is given to the wheel inside the turning circle.
JP-A-8-282231

  However, in the apparatus disclosed in Patent Document 1, the amount of increase / decrease in camber angle is simply proportional to the steering angle of the wheel, while the camber angle during turning of the vehicle is such that the vehicle speed is high and the load is small or large. Since this also changes depending on other factors such as the above, there is a problem in that stable turning cannot be performed.

  Further, in the device disclosed in Patent Document 1, since the position of the pivot portion on the vehicle body side of the upper arm changes, it is difficult to increase the rigidity of the pivot portion, the suspension rigidity of the vehicle body is insufficient, the ride comfort is deteriorated, There are problems such as poor steering.

  In addition, there is a camber angle control device that includes an actuator that can change the camber angle, and that controls the camber angle to increase or decrease by operating this actuator during turning, but this type of camber angle control device Regardless of whether the camber angle is maintained near zero, the stability during turning can be improved, but the cornering force required for turning is not sufficient and the steering feel is deteriorated. There is a problem of being invited.

  The present invention has been made in view of such circumstances, and appropriately uses a canvas last applied to a wheel provided with a camber angle as a cornering force to improve stability during turning and provide a good steering feeling. It aims at providing the camber angle control apparatus which can be made to make compatible.

  A camber angle control device according to a first aspect of the present invention suspends and supports a vehicle body via an upper arm and a lower arm, and controls a steering wheel connected to a steering mechanism via a tie rod, and increases or decreases the camber angle of the wheel. In a vehicle camber angle control device comprising: an actuator; and a control unit that operates the actuator during turning of the vehicle and controls increase / decrease of the camber angle of the wheel so as to obtain a desired turning performance. A camber angle calculating means for calculating a camber angle of the wheel based on a detection result of a roll angle of the vehicle and an operation amount of the actuator, and a slip for calculating a slip angle of the wheel based on a detection result of the turning state of the vehicle Based on angle calculation means, calculation results of the camber angle calculation means and slip angle calculation means, and the load applied to the wheel A calculation means for predicting and calculating a cornering force and a canvas last acting on the wheel, and the actuator is operated to maximize the sum of the predicted values of the cornering force and the canvas last calculated by the calculation means. It is characterized by being.

  In the camber angle control device according to the second invention of the present invention, the actuator according to the first invention is interposed between the connecting portion of the upper arm to the wheel and the tie rod, and the connecting portion is arranged in the longitudinal direction of the upper arm. It is characterized by comprising a cylinder that expands and contracts to push and pull in the direction.

  In the camber angle control device according to the first aspect of the present invention, the cornering force and the canvas last applied to the steering wheel during the turning of the vehicle are predicted and calculated, and the sum of these is calculated, and the wheel is directed toward the inside of the turning circle. In order to maximize the total cornering force applied, the actuator is operated and the camber angle is controlled to increase / decrease, so that both stability during turning and good steering feel can be achieved, and the turning performance of the vehicle is improved. It becomes possible.

  In the camber angle control device according to the second aspect of the invention, the actuator for increasing or decreasing the camber angle is interposed between the connecting portion of the steering wheel to the upper arm and the tie rod that connects the steering wheel to the steering mechanism. Therefore, the movement of the tie rod for steering can be used to increase / decrease the camber angle, the operation amount of the actuator for increasing / decreasing the camber angle can be suppressed, and the responsiveness of the camber angle control can be improved. The present invention has an excellent effect that the pivot position of the upper arm on the vehicle body side does not change, and it is possible to prevent inconveniences such as deterioration in riding comfort and steering performance due to insufficient suspension rigidity.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic diagram showing a configuration of a camber angle control device according to the present invention. In the figure, 1 is a steering wheel, and 2 is a vehicle body suspended by a wheel 1. The wheel 1 is supported by an upper arm 3 and a lower arm 4 inside a wheel house 20 provided on a side surface of the vehicle body 2. Has been.

  The wheel 1 is rotatably supported by a knuckle 12 via an axle 11 protruding from the axis of the hub 10. The knuckle 12 is integrally provided with support arms 13 and 14 extending vertically. The upper support arm 13 is at the tip of the upper arm 3 and the lower support arm 14 is at the tip of the lower arm 4. It is connected via a ball joint. The knuckle 12 connected in this way can rotate around a kingpin axis K connecting the connecting portions with both arms 3 and 4 while changing the tilting posture with respect to the upper arm 3 and the lower arm 4.

  The base ends of the upper arm 3 and the lower arm 4 extending inward of the wheel house 20 are pivotally supported by the pivots 30 and 40 that are spaced apart from each other so as to freely swing in the vertical direction. Further, the middle part of the lower arm 4 pivotally supported at the lower position is connected to a part of the vehicle body 2 above the wheel house 20 via a known suspension unit 5 coaxially provided with a coil spring and a damper. The swinging of the upper arm 3 is configured to occur against the spring force of the coil spring and accompanying expansion / contraction of the suspension unit 5 under the damping by the damper.

  The above suspension system is, for example, a system known as a double wishbone system using one V-shaped upper arm 3 and one lower arm 4 each having a bifurcated pivot portion for pivots 30 and 40 on the vehicle body 2 side. However, one or both of the upper arm 3 and the lower arm 4 may be configured using a plurality of I-shaped arms.

  Further, the knuckle 12 includes a knuckle arm 15 that extends obliquely forward or obliquely rearward from the inner surface, either integrally or separately. The knuckle arm 15 is connected to a steering mechanism (not shown) via a tie rod 16, and is configured to be pushed and pulled via the tie rod 16 by the operation of the steering mechanism. By this pushing and pulling, the knuckle 12 rotates about the kingpin axis K, and the wheel 1 supported by the knuckle 12 by this rotation is steered according to the operation of the steering mechanism.

  Further, a slider 31 that is movable in the longitudinal direction of the upper arm 3 is interposed at the connecting portion of the knuckle 12 to the tip of the upper arm 3, and the slider 31 is pivotally supported in the middle of the tie rod 16. It is connected to the output end of the camber angle adjusting actuator 6. The actuator 6 can be, for example, a hydraulic cylinder that expands and contracts according to the supply and discharge of hydraulic pressure. The actuator 6 moves the slider 31 toward the distal end side of the upper arm 3 when extended, and the proximal end side of the upper arm 3 when contracted. The slider 31 is configured to move toward the.

  As shown in the figure, the wheel 1 supported as described above has its lower peripheral surface grounded to the road surface R, suspends the vehicle body 2, and rolls on the road surface R by rotation about the axle 11. To run. Further, as described above, the wheel 1 is steered by turning about the kingpin axis K together with the knuckle 12 in accordance with the pushing and pulling of the knuckle arm 15 by the tie rod 16, and the vehicle turns in this steering direction.

  During this travel, the wheel 1 and the vehicle body 2 are displaced relative to each other in the vertical direction by the action of an external force such as a reaction force applied to the wheel 1 from the road surface R and a centrifugal force applied to the vehicle body 2. Absorbed by swinging of the upper arm 3 and the lower arm 4 accompanying expansion and contraction of the suspension unit 5 as a damping element, the vehicle body 2 can maintain a stable suspension posture.

  During this travel, the camber angle adjusting actuator 6 arranged as described above is expanded and contracted to increase or decrease the inclination angle of the wheel 1 with respect to the vertical line of the road surface R, that is, the camber angle. FIG. 2 is an explanatory diagram of the operation of the actuator 6.

  FIG. 2A shows a state where the actuator 6 is shortened. In this case, the slider 31 connected to the output end of the actuator 6 moves to the base end side of the upper arm 3 as shown in the figure, and the connecting portion of the knuckle 12 to the upper arm 3 is inside the connecting portion to the lower arm 4. The wheel 1 supported by the knuckle 12 is given a camber angle (negative camber) that is inclined with the upper portion facing inward.

  FIG. 2B shows a state where the actuator 6 is extended. In this case, the slider 31 connected to the output end of the actuator 6 moves to the distal end side of the upper arm 3 as shown in the figure, and the connecting portion of the knuckle 12 to the upper arm 3 is outside the connecting portion to the lower arm 4. The wheel 1 supported by the knuckle 12 is given a camber angle (positive camber) that inclines with the upper part facing outward.

Thus, the camber angle of the wheel 1 is increased / decreased according to the expansion / contraction operation of the actuator 6, and the wheel 1 to which the camber angle is given in this way is inclined as shown by an arrow in FIG. 2. Lateral force (canvas last) _FT is added. In the present invention, the camber thrust F _T applied to this, in order to use as a force for assisting the turning of the vehicle with cornering force as a deformation restoring force of the wheel 1 due to friction with the road surface R, as follows camber Angle control is performed.

  Since the actuator 6 is supported in the middle of the tie rod 16 that pushes and pulls the wheel 1 for steering as described above, the camber angle of the wheel 1 is determined by the movement of the support portion of the actuator 6 by the forward / backward movement of the tie rod 16. The positive camber is given on the advance side of the tie rod 16 and the negative camber is also given on the retreat side. Here, in the present invention, the steering of the wheel 1 by the forward / backward movement of the tie rod 16 is configured such that the front is generated outward when the vehicle is advanced and the front is generated inward when the vehicle is retracted. Thus, the change in camber angle due to the forward / backward movement of the tie rod 16 for steering is configured such that a negative camber is given to the wheel 1 outside the turning circle and a positive camber is given to the wheel 1 inside the turning circle.

  As shown in FIG. 1, the actuator 6 is expanded and contracted according to an operation command given from the camber angle control unit 7. The camber angle control unit 7 is configured as an electronic control unit including a CPU as a calculation processing unit, a ROM storing a control program, and a RAM storing constant values, maps, and the like used for calculation, The camber angle control unit 7 is given a detection result of the expansion / contraction position of the actuator 6 from a stroke sensor 60 attached to the actuator 6, and from a roll angle sensor 70 provided at an appropriate part of the vehicle body 2, The detection result of the roll angle of the vehicle body 2 is given.

  Here, the roll angle is an inclination angle generated in the vehicle body 2 with the outside of the turning circle down due to the action of centrifugal force during the turning of the vehicle, and the roll angle sensor 70 outputs directly corresponding to the roll angle. Can be configured with a free gyro, and the configuration can also be such that the roll angular velocity given as the output of the rate gyro is detected as a result of integration.

  Further, the camber angle control unit 7 is provided with the detection result of the traveling speed of the vehicle from the vehicle speed sensor 71, and the detection result of the steering angle of the wheel 1 is provided from the steering angle sensor 72. The load sensor 73 gives the detection result of the load applied to the.

  FIG. 3 is a flowchart showing the operation content of the camber angle control unit 7. The operation of the camber angle control unit 7 according to this flowchart is an operation that is repeatedly performed every predetermined control period during high-speed traveling when the vehicle speed detected by the vehicle speed sensor 70 exceeds the preset lower limit vehicle speed. 7. First, the detection value of each sensor given to the input side is fetched (step 1), and then the camber angle of the wheel 1 is calculated (step 2).

  As described above, the camber angle of the wheel 1 changes according to the expansion / contraction operation of the actuator 6 and the advance / retreat operation of the tie rod 16 for steering the wheel 1, and is applied to the vehicle body 2 due to the centrifugal force during turning. It changes also with the roll which arises, The positive camber equivalent to a roll angle is given to the wheel 1 outside a turning circle, and the negative camber equivalent to a roll angle is given to the wheel 1 inside a turning circle.

  In the calculation of the camber angle in the step 2, first, the advance / retreat position of the tie rod 16 is obtained from the steering angle taken in as the detection value of the steering angle sensor 72, and this result and the actuator 6 taken in as the detection value of the stroke sensor 60 are obtained. The camber angle of the wheel 1 with respect to the vehicle body 2 is obtained using the expansion / contraction position of the vehicle, and based on the roll angle taken as a detection value of the roll angle sensor 70 on the result, the wheel 1 outside the turning circle is moved to the positive side. For the wheels 1 inside the turning circle, the correction is made to the negative side.

Then camber angle control unit 7, the camber angle calculated in step 2, the camber thrust F _T and prediction calculation applied to the wheel 1 with the additional load to the wheel 1 taken as the detection value of the load sensor 73 (Step 3) Further, the cornering force F _C applied to the wheel 1 is predicted by using the vehicle speed and the steering angle taken as the detection values of the vehicle speed sensor 71 and the steering angle sensor 72, and the camber angle and the additional load, respectively. (Step 4).

FIG. 4 is a diagram illustrating the generation behavior of the canvas last. As shown in the figure, the canvas last exhibits a characteristic that increases in proportion to the increase in camber angle, and the magnitude of the increase rate corresponds to the magnitude of the applied load to the wheel 1. Prediction calculation of camber thrust F _T in step 3, for example, in FIG. 4 which had been stored in the map into state RAM, made by applying the detection values of the camber angle and the additional load.

FIG. 5 is a diagram illustrating the generation behavior of the cornering force. As shown in the figure, the cornering force increases in proportion to the increase of the slip angle of the wheel 1 and exhibits a characteristic that balances when the upper limit slip angle is reached. Corresponds to the magnitude of the additional load to 1. The slip angle can be calculated by using the vehicle speed and the steering angle. For example, the calculation of the cornering force F _C in Step 4 is mapped and stored in the RAM as shown in FIG. A standard value is obtained by applying the detected value of the additional load, and this value is reduced by a procedure for reducing the amount according to the camber angle generated on the positive side and the negative side.

The generation behavior of the canvas last shown in FIG. 4 and the generation behavior of the cornering force shown in FIG. 5 are affected by the state of the tire, such as the type of tire used as the wheel 1, the air pressure of the tire, etc. to map the occurrence behavior of each for each state of the tire, to predict calculating the camber thrust F _T and cornering force F _C by selectively using the corresponding map is desirable.

Then camber angle control unit 7 calculates the total cornering force _{F (= F T + F C} ) which acts on the wheel 1 toward the inside of the predicted computed camber thrust by adding F _T and cornering force F _C, the turning circle (Step 5). At this time, always treated as cornering force F _C is positive that occurs towards the inside of the turning circle, camber thrust F _T generated in the direction of inclination of the wheel 1, for the wheel 1 inside of the turning circle, positive The thing by camber is made into a positive value, and the thing by negative camber is handled as a positive value about the wheel 1 outside the turning circle.

Next, the camber angle control unit 7 temporarily increases or decreases the camber angle for each predetermined unit width (step 6), and determines whether the camber angle is within a range that can be changed by the operation of the actuator 6 ( Step 7), if it is within the changeable range (Step 7: YES), return to Step 3 and perform the operation for obtaining the canvas last F _T , cornering force F _C and total cornering force F using the respective camber angles. repeat.

  On the other hand, when the increase / decrease of the camber angle within the changeable range is completed (step 7: NO), the calculated values of the total cornering force F in each are compared, and the camber angle at which this value becomes maximum is determined. The optimum camber angle is selected (step 8), an operation command is issued to the actuator 6 to realize the optimum camber angle, the actuator 6 is expanded and contracted (step 9), and the series of operations is terminated.

By the above operation, in each of the case where the entire area in the range achievable by expansion and contraction of the actuator 6 to change the camber angle for each predetermined width, camber thrust F _T and cornering force F _C is calculated, both The camber angle that maximizes the total cornering force F given as the sum is determined as the optimal camber angle, and the optimal camber angle determined in this way is realized by the expansion and contraction operation of the actuator 6.

  Since the change in the total cornering force F according to the increase / decrease in the camber angle occurs as a continuous change, the camber angle is increased or decreased in step 6 and the process returns to step 3, and the total cornering force F is calculated in step 5. Each time this value is compared with the previous calculated value, if it is smaller than the previous value, the change of the camber angle to the subsequent increase or decrease side may be omitted. As a result, the number of repetitions can be reduced.

FIG. 6 is a schematic diagram illustrating a state during turning of a vehicle including the camber angle control device according to the present invention. When turning in the direction indicated by the arrow in the figure, the vehicle body 2 rolls around the center of gravity G as indicated by the white arrow, and a negative camber is placed on the wheel 1 outside the turning circle. positive camber is provided respectively on the inside of the wheel 1, the cornering force F _C and camber thrust F _T of the same orientation, will be added to these sum (= F _C + F _T) and the maximum, the turning Due to the action of these forces toward the inside of the circle, the vehicle can be made to turn reliably and stably.

  Here, the actuator 6 that expands and contracts to give the camber angle as described above is supported in the middle of the tie rod 16 that pushes and pulls the left and right wheels 1 and 1 for steering. Is also changed by the movement of the support portion of the actuator 6 due to the forward / backward movement of the corresponding tie rod 16, and as described above, this change is caused by the negative camber on the wheel 1 outside the turning circle and the wheel 1 inside the turning circle. Each of the positive cambers is given, that is, the camber angle having the same direction as the camber angle realized by the above-described operation of the camber angle control unit 7 is given. Therefore, the optimum camber angle determined by the camber angle control unit 7 is realized by slightly extending and retracting the actuator 6. Camber angle control that quickly follows the state change during turning is possible.

It is a schematic diagram which shows the structure of the camber angle control apparatus which concerns on this invention. It is operation | movement explanatory drawing of an actuator. It is a flowchart which shows the operation | movement content of a camber angle control part. It is a figure which shows the generation | occurrence | production behavior of canvas last. It is a figure which shows the generation | occurrence | production behavior of a cornering force. It is a schematic diagram which shows the state at the time of turning driving | running | working of a vehicle provided with the camber angle control apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wheel 2 Car body 3 Upper arm 4 Lower arm 6 Actuator 7 Camber angle control part (control means)
16 Tie Rod F _C Cornering Force F _T Canvas Last

Claims (2)

The vehicle body is suspended and supported via an upper arm and a lower arm, a steering wheel connected to a steering mechanism via a tie rod, an actuator for increasing or decreasing a camber angle of the wheel, and the actuator is operated when the vehicle is turning, In a camber angle control device for a vehicle, comprising control means for increasing / decreasing the camber angle of the wheel to obtain a desired turning performance,
The control means includes
Camber angle calculating means for calculating a camber angle of the wheel based on a detection result of a roll angle of the vehicle and an operation amount of the actuator;
Slip angle calculating means for calculating a slip angle of the wheel based on a detection result of the turning state of the vehicle;
Computation means for predicting and calculating the cornering force and canvas last acting on the wheel based on the calculation result of the camber angle calculation means and the slip angle calculation means, and the load applied to the wheel,
A camber angle control device characterized in that the actuator is operated so as to maximize the sum of the predicted values of the cornering force and canvas last calculated by the calculating means.   The actuator is constituted by a cylinder which is interposed between a connecting portion of the upper arm to the wheel and the tie rod and which expands and contracts to push and pull the connecting portion in the longitudinal direction of the upper arm. The camber angle control device according to 1.

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