JP2010012878A - Wheel load ratio detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve installability of an apparatus on a vehicle by restraining an increase in the cost necessary for detecting a wheel load. <P>SOLUTION: The wheel load ratio detector 10a includes: respective wheel speed sensor 45 for detecting a wheel speed of a vehicle; respective brake torque sensors 46 for detecting a break torque of respective wheels of the vehicle; and a ground point μ computation part 51 which takes a ratio of a brake torque T of the respective wheels detected by the respective brake torque sensors 46 as a ratio of a wheel load of the respective wheels when a deviation between a front wheel speed and a rear wheel speed corresponding to the wheel speed detected by the respective wheel speed sensors 45 satisfies a predetermined value VWO or less. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wheel load ratio detection device for a vehicle.

Conventionally, for example, a wheel load detection device including a load sensor that detects a load acting on each wheel of a vehicle is known (see, for example, Patent Document 1).
JP 2006-64650 A

By the way, according to the wheel load detection device according to the above-described prior art, the load sensor detects the load of the wheel by detecting the stress change of the magnetostrictive material according to the axial force acting on the wheel bearing device. The magnetostrictive material and the detection unit are provided. However, such a wheel load detection device is expensive, and it is necessary to secure a dedicated mounting space only for detecting the wheel load, and it is difficult to reduce costs and improve vehicle mounting properties. Occurs.
The present invention has been made in view of the above circumstances, and provides a wheel load ratio detection device capable of suppressing an increase in the cost required to detect a wheel load and improving the vehicle mountability of the device. It is an object.

  In order to solve the above-described problems and achieve the object, the wheel load ratio detection device according to the first aspect of the present invention detects a vehicle speed state quantity (for example, a wheel speed or a vehicle speed in the embodiment). Speed state quantity detecting means (for example, each wheel speed sensor 45 or speed sensor in the embodiment) and braking for detecting the braking torque of each wheel of the vehicle (for example, each brake torque T in the embodiment) Torque detection means (for example, each brake torque sensor 46 in the embodiment, or each hydraulic pressure sensor 61 and the ground point μ calculation unit 51) and the speed state quantity detected by the speed state quantity detection means are predetermined conditions. Each vehicle detected by the braking torque detecting means when the deviation between the front wheel speed and the rear wheel speed in the embodiment satisfies a predetermined value VW0 or less or the vehicle speed is a predetermined vehicle speed or less. The ratio of the braking torque, said and a ratio calculating means for the ratio of the wheel load of each wheel (e.g., ground point μ calculating section 51 in the embodiment).

  According to the wheel load ratio detection device according to the first aspect of the present invention, the wheel load ratio (wheel load ratio) of each wheel based on the outputs of the speed state quantity detection means and the braking torque detection means previously mounted on the vehicle. Can be detected, and the load (wheel load) of each wheel of the vehicle can be easily calculated from the wheel load ratio. This prevents the vehicle from having to have a space for mounting a dedicated device for detecting the wheel load ratio and wheel load, and increases the cost required to detect the wheel load ratio and wheel load. Can be suppressed.

Hereinafter, a wheel load ratio detection device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
The wheel load ratio detection device 10a according to the present embodiment is provided in, for example, a vehicle antilock control device 10, and this antilock control device 10 controls, for example, a vehicle brake device 10b shown in FIG.

  The brake device 10b includes a master cylinder 2 as a brake fluid pressure generator that generates brake fluid pressure by operating the brake pedal 1 by a driver. The master cylinder 2 includes, for example, each of the left front wheel FL and the right rear wheel RR. An output port 4 connected to the wheel cylinders 3a and 3b and an output port 5 connected to the wheel cylinders 3c and 3d of the right front wheel FR and the left rear wheel RL are provided.

The output port 4 of the master cylinder 2 and the wheel cylinders 3a and 3b of the left front wheel FL and the right rear wheel RR are connected by a connection path 11, and each wheel cylinder 3a and 3b is connected to the connection path 11 in parallel. The normally open solenoid valves 12 and 12 are inserted in the front.
Each wheel cylinder 3a, 3b and a reservoir 13 for releasing the brake fluid pressure in each wheel cylinder 3a, 3b are connected by a release path 14, and the release path 14 is parallel to each wheel cylinder 3a, 3b. Normally closed solenoid valves 15 and 15 are inserted.

  Brake fluid sent from the wheel cylinders 3a and 3b is stored in the reservoir 13, and this brake fluid is a return path in which a damper chamber 17 for absorbing pump pulsation provided upstream of the pump 16 and the pump 16 is inserted. 18 is returned to the master cylinder 2 side.

  Further, a check valve 19 that allows the brake fluid to flow from the wheel cylinders 3a, 3b to the master cylinder 2 side is provided in parallel with the normally open solenoid valve 12, and from the wheel cylinders 3a, 3b to the master cylinder 2 side. Check valves 20 and 21 that allow the brake fluid to flow are provided in series on the upstream side and the downstream side of the pump 16.

The output port 5 of the master cylinder 2 and the wheel cylinders 3c, 3d of the right front wheel FR and the left rear wheel RL are connected by a connection path 31, and the wheel cylinders 3c, 3d are parallel to the connection path 31. Normally-open type solenoid valves 32 and 32 are inserted in the front.
Each wheel cylinder 3c, 3d and a reservoir 33 for releasing the brake fluid pressure in each wheel cylinder 3c, 3d are connected by a release path 34, and the release path 34 is connected in parallel to each wheel cylinder 3c, 3d. Normally closed solenoid valves 35 and 35 are inserted.

  Brake fluid sent from the wheel cylinders 3c and 3d is stored in the reservoir 33, and this brake fluid is a return path in which a damper chamber 37 for absorbing pump pulsation provided upstream of the pump 36 and the pump 36 is inserted. 38 is returned to the master cylinder 2 side.

  In addition, a check valve 39 that allows the brake fluid to flow from the wheel cylinders 3c, 3d to the master cylinder 2 side is provided in parallel with the normally open solenoid valve 32, and from the wheel cylinders 3c, 3d to the master cylinder 2 side. Check valves 40 and 41 that allow the brake fluid to flow are provided in series on the upstream side and the downstream side of the pump 36.

The normally open solenoid valves 12 and 32 are in communication with each other by the elastic force of the return springs 12b and 32b when the solenoids 12a and 32a are not energized, and the brake fluid pressure of the master cylinder 2 increases the wheel cylinder pressure.
Further, when the solenoids 12a and 32a are energized, they are cut off against the elastic force of the return springs 12b and 32b, and the wheel cylinder pressure is maintained.

  The normally closed solenoid valves 15 and 35 are cut off by the elastic force of the return springs 15b and 35b when the solenoids 15a and 35a are not energized. When the solenoids 15a and 35a are energized, the solenoids 15a and 35b are in communication with each other against the elastic force of the return springs 15b and 35b. The pressure is reduced.

The normally open solenoid valves 12 and 32 are normally opened at a normal position where no current is applied, and are moved to a closed state at a switching position by energization. The normally closed solenoid valves 15 and 35 are normally closed at a normal position where no current is supplied. The reason for shifting to the open state at the switching position by energization is because of the so-called fail-safe relationship in the case of abnormal operation compensation.
In the normally open solenoid valves 12 and 32, when the brake fluid pressure works from the master cylinder 2 side via the connection paths 11 and 31, the brake fluid pressure is in the same direction as the urging direction of the return springs 12b and 32b. That is, it acts in the direction leading to the open state.

The normally open solenoid valves 12 and 32, the normally closed solenoid valves 15 and 35, and the motors (not shown) for driving the pumps 16 and 36 are controlled by the antilock control device 10.
The antilock control device 10 is output from each wheel speed sensor 45 that detects each speed (each wheel speed VW (j); j = 1,..., 4) of the left and right front wheels FL, FR and rear wheels RL, RR. Based on the detected signal, it is detected whether or not each wheel FL, FR, RL, RR has a locking tendency, and the brake fluid pressure of each wheel cylinder 3a, 3b, 3c, 3d is determined according to the detection result. The decompression mode in which the normally open solenoid valves 12 and 32 are closed and the normally closed solenoid valves 15 and 35 are opened, and the normally open solenoid valves 12 and 32 are closed and the normally closed types are closed. Either a holding mode in which the solenoid valves 15 and 35 are closed, or a pressure increasing mode in which the normally open solenoid valves 12 and 32 are opened and the normally closed solenoid valves 15 and 35 are closed ( (ABS control mode).

For example, as shown in FIG. 2, the antilock control device 10 includes a ground contact point μ calculation unit 51, a vehicle body deceleration calculation unit 52, a vehicle body speed calculation unit 53, a peak μ determination unit 54, and a target wheel speed calculation unit. 55, a wheel speed deviation calculation unit 56, a target torque calculation unit 57, a torque deviation calculation unit 58, and a valve control unit 59.
The wheel load ratio detection device 10a includes, for example, a ground contact point μ calculation unit 51, wheel speed sensors 45, and brake torque sensors 46.

The ground point μ calculation unit 51 outputs from each wheel speed sensor 45 that detects each speed (each wheel speed VW (j); j = 1,..., 4) of the left and right front wheels FL, FR and rear wheels RL, RR. Output from each brake torque sensor 46 that detects the detected torque and brake torque T (T (j); j = 1,..., 4) acting on the left and right front wheels FL, FR and rear wheels RL, RR. Based on the detection signal, for example, each physical quantity shown in FIG. 3 (that is, the brake torque T, the wheel inertia moment I, the wheel radius RW, the time differential (dω / dt) of the wheel rotational speed ω, and the wheel load From the following formula (1) according to W), the contact point μ of each wheel (the friction coefficient at the contact point of each wheel) is calculated.
Note that the brake torque sensor 46 includes, for example, a strain gauge that detects distortion generated when the brake torque is applied to the brake caliper.

  In the above formula (1), each wheel load W is calculated by multiplying the vehicle weight M by each wheel load ratio.

By the way, as shown in FIG. 4, for example, a slip rate region where the anti-lock control (ABS control) is not activated, for example, the wheel speed of the driving wheel (for example, the average value of the wheel speeds of the left and right front wheels FL, FR). : Front wheel speed) and the wheel speed of the driven wheel (for example, the average value of the wheel speeds of the left and right rear wheels RL, RR: rear wheel speed) in a region where the deviation is less than or equal to a predetermined value VW0, The longitudinal force (corresponding to the frictional force when the lateral force can be ignored) is a constant correspondence relationship regardless of the magnitude of the wheel load (eg, 3000N, 4500N, and 6000N in FIG. 4). .
Accordingly, based on the following general formula (2), the brake torque of the drive wheel (for example, the sum of the brake torques of the left and right front wheels FL and FR: front brake torque TF) and the wheel load of the drive wheel (for example, Sum of wheel loads of left and right front wheels FL, FR: front wheel load WF), brake torque of driven wheels (for example, sum of brake torques of left and right rear wheels RL, RR: rear brake torque TR), subordinate The following formula (3) is established for the wheel load of the moving wheel (for example, the sum of the wheel loads of the left and right rear wheels RL and RR: the rear wheel load WR).

  The above formula (3) is described as shown in the following formula (4), and the ratio between the front brake torque TF and the rear brake torque TR is equal to the ratio between the front wheel load WF and the rear wheel load WR, For example, as shown in FIG. 5, the time series change slope φ2 of the front brake torque TF and the rear brake torque TR in the wheel load calculation region where the deviation between the front wheel speed and the rear wheel speed is a predetermined value VW0 or less. It becomes equal to the ratio with the gradient φ1 of the series change.

  That is, the time series of the front brake torque TF and the rear brake torque TR based on the detection signal output from each brake torque sensor 46 in the wheel load calculation region where the deviation between the front wheel speed and the rear wheel speed is equal to or less than the predetermined value VW0. In the change, the ratio between the time series change slope φ2 of the front brake torque TF and the time series change slope φ1 of the rear brake torque TR is calculated at a plurality of different timings, and the calculation result data is accumulated, for example, accumulated. By calculating the average value of the data and the like, the calculation accuracy of the ratio between the front wheel load WF and the rear wheel load WR can be improved.

Further, after calculating the ratio between the front wheel load WF and the rear wheel load WR, the left and right front wheels FL, FR and rear wheels RL, which are output from the brake torque sensors 46 on the front wheel side and the rear wheel side, respectively. A wheel load ratio for each wheel can be calculated based on each brake torque T (T (j); j = 1,..., 4) acting on RR.
That is, in the same manner as the above formula (4), for example, as shown in the following formula (5), on the front wheel side, the brake torques T (j) of the left and right front wheels FL and FR; (j = 1, 2) The ratio is equivalent to the ratio of the left and right wheel loads WFL, WFR, and when the brake torques T (j) of the left and right front wheels FL, FR in the wheel load calculation region (j = 1, 2) It becomes equal to the ratio of the slope of the series change. On the rear wheel side, the ratio of the brake torques T (j); (j = 3, 4) of the left and right rear wheels RL, RR is equal to the ratio of the left and right wheel loads WRL, WRR. The time series of the brake torques T (j) of the left and right rear wheels RL and RR in the wheel load calculation region where the deviation between the front wheel speed and the rear wheel speed is equal to or less than a predetermined value VW0; (j = 3, 4) It becomes equal to the ratio of the slope of change.
In this case, the wheel load calculation area is an area in which, for example, the deviation between the front wheel speed and the rear wheel speed is equal to or less than a predetermined value VW0 and is substantially zero.

  For example, in FIG. 5, the left and right front wheels FL and FR that are drive wheels after time ta when the wheel load calculation area is released when the deviation between the front wheel speed and the rear wheel speed becomes larger than a predetermined value VW0. When the time tb at which the deviation between the front wheel speed and the rear wheel speed increases to a predetermined value or more is reached due to the increase in the slip of the wheel and the relative decrease in the front wheel speed, the ABS control region is set. Then, the anti-lock control operation is started. Accordingly, the front brake torque TF changes according to the antilock control after the time tb.

Further, the vehicle weight M is determined by, for example, as shown in FIG. 6, the brake torque (four-wheel brake torque) of the left and right front wheels FL and FR and the rear wheels RL and RR set in advance and the wheel speeds VW (j). ; Estimated based on a predetermined correspondence between the average value (wheel speed) of (j = 1,..., 4) and the vehicle weight M (for example, M1>M2> M3).
That is, in braking at a reduced speed that does not activate the antilock control, the four-wheel brake torque is calculated based on the detection signal output from each brake torque sensor 46, and each wheel speed VW (j); (j = 1, .., 4) is calculated based on the detection signal output from each wheel speed sensor 45. And, as the four-wheel brake torque increases between the four-wheel brake torque and the average value of each wheel speed VW (j); (j = 1,..., 4), each wheel speed VW (j ); (J = 1,..., 4) in which the average value changes in a decreasing trend. Further, as the vehicle weight M is smaller (M1>M2> M3), each of the four-wheel brake torque increases. The reduction degree of the average value of the wheel speed VW (j); (j = 1,..., 4) is increased.

  The vehicle body deceleration calculation unit 52 is described based on the ground contact point μ of each wheel output from the contact point μ calculation unit 51 and the predetermined constant GR0FS, for example, as shown in the following equation (6). (That is, each vehicle body deceleration GRDAT (j); j = 1,..., 4) calculated based on the respective ground contact points μ for the left and right front wheels FL, FR and rear wheels RL, RR.

  For example, the vehicle body speed calculation unit 53 includes a deceleration ΔV described as shown in the following formula (7), that is, each vehicle body deceleration GRDAT (j) (j = 1,..., Output from the vehicle body deceleration calculation unit 52. By adding the minimum value of 4) to the vehicle speed VR0 (k−1) calculated in the previous calculation process, for example, as shown in the following formula (8), the vehicle speed in the current calculation process Calculate VR0 (k). The following mathematical formula (8) is described by an arbitrary natural number k.

  The peak μ determination unit 54 is output from each wheel speed sensor 45 that detects each speed (each wheel speed VW (j); j = 1,..., 4) of the left and right front wheels FL, FR and rear wheels RL, RR. The maximum value of the contact point μ of each wheel (the friction coefficient at the contact point of each wheel) is detected based on the detected signal, and this maximum value is output as the peak μ.

  The target wheel speed calculation unit 55 outputs the vehicle body speed VR0 output from the vehicle body speed calculation unit 53 (that is, the vehicle body speed VR0 (k) in the current calculation process) and the peak μ output from the peak μ determination unit 54. Based on the predetermined constant a, a target wheel speed VWt described as shown in the following formula (9) is calculated.

  The wheel speed deviation calculating unit 56 outputs each wheel speed VW output from each wheel speed sensor 45 (that is, each wheel speed VW (j) of the left and right front wheels FL, FR and rear wheels RL, RR; j = 1,..., The deviation (VWt−VW) between the detection signal of 4) and the target wheel speed VWt output from the target wheel speed calculation unit 55 is calculated.

  The target torque calculation unit 57 includes a deviation (VWt−VW) of each wheel output from the wheel speed deviation calculation unit 56, a detection signal of the brake torque T of each wheel output from each brake torque sensor 46, and a predetermined signal. Based on the conversion coefficient α and a predetermined wheel inertia moment I, a target brake torque Tt of each wheel described as shown in the following formula (10) is calculated.

  The torque deviation calculation unit 58 is configured to generate a brake torque deviation (Tt) between the target brake torque Tt of each wheel output from the target torque calculation unit 57 and the detection signal of the brake torque T of each wheel output from each brake torque sensor 46. -T) is calculated.

When the anti-lock control device 10 selects execution of any one of the pressure reducing mode, the holding mode, and the pressure increasing mode, the valve control unit 59 selects the electromagnetic valves 12 and 15 corresponding to the selected mode. , 32 and 35 are controlled.
Further, the valve control unit 59 sets the brake torque deviation (Tt−T) to zero based on the brake torque deviation (Tt−T) of each wheel output from the torque deviation calculation unit 58, for example. The brake fluid pressure of each wheel cylinder 3a, 3b, 3c, 3d is controlled by opening and closing the valves 12, 15, 32, 35.

In particular, the valve control unit 59 opens the first increase mode and the first increase mode as the pressure increase mode for opening the normally open solenoid valves 12 and 32 and closing the normally closed solenoid valves 15 and 35. And a second increase mode in which a smaller brake torque T is applied, and when the brake torque deviation (Tt-T) is equal to or greater than a predetermined value, the responsiveness to wheel speed fluctuations is emphasized and is relatively large. When the first pressure increasing mode for applying the brake torque T is selected and the brake torque deviation (Tt-T) is less than the predetermined value, it is important to reduce the longitudinal vibration of the vehicle body through detailed control of the wheel speed fluctuation. Thus, by selecting the second pressure increasing mode that applies a relatively small brake torque T, an appropriate brake torque T is applied to each wheel.
Here, the first increase mode is a mode instructing, for example, opening of the normally open solenoid valves 12 and 32 and closing of the normally closed solenoid valves 15 and 35, and the second increase mode is, for example, In addition to instructing the normally closed solenoid valves 15 and 35 to close, the duty increase is performed by controlling the duty ratio of the normally open solenoid valves 12 and 32 by PWM (Pulse Width Modulation) control.

  The antilock control device 10 according to the present embodiment has the above-described configuration. Next, the operation of the antilock control device 10 will be described.

First, for example, in step S01 shown in FIG. 7, on the basis of the detection signals output from the wheel speed sensors 45, the speeds of the left and right front wheels FL, FR and rear wheels RL, RR (each wheel speed VW (j); j = 1,..., 4) are acquired.
Next, in step S02, the slip ratio of each wheel is calculated.
Next, in step S03, it is detected whether or not each wheel FL, FR, RL, RR has a locking tendency, and each normally open type electromagnetic valve 12, 32 is closed according to the detection result. Depressurization mode for opening each normally closed solenoid valve 15, 35, holding mode for closing each normally open solenoid valve 12, 32 and closing each normally closed solenoid valve 15, 35, One mode (ABS control mode) is selected from the pressure increasing mode in which the open solenoid valves 12 and 32 are opened and the normally closed solenoid valves 15 and 35 are closed.

  Next, in step S04, based on the detection signals output from each wheel speed sensor 45 and each brake torque sensor 46, each wheel FL, FR, RL, RR according to the above formulas (1) to (10). Target brake torque Tt is calculated.

  In this step S04, particularly when calculating the wheel load ratio of each wheel multiplied by the vehicle weight M when calculating each wheel load W, first, the anti-lock control (ABS control) is not activated. In a low slip ratio region, for example, a wheel load calculation region in which the deviation between the front wheel speed and the rear wheel speed is equal to or less than a predetermined value VW0, the front brake torque TF and the rear brake based on the detection signals output from the respective brake torque sensors 46 In the time series change of the torque TR, the ratio of the slope φ2 of the time series change of the front brake torque TF and the slope φ1 of the time series change of the rear brake torque TR is calculated at a plurality of different timings. For example, an average value of the accumulated data is calculated. This calculation result is a ratio of the front wheel load WF and the rear wheel load WR.

Next, in the wheel load calculation region with a slip ratio that is low enough that the anti-lock control (ABS control) does not operate, the left and right front wheels FL, FR and rear wheels RL, RR that are output from each brake torque sensor 46 are applied. In the time series change of the brake torque T (T (j); j = 1,..., 4), the brake torque T (j) of the left and right front wheels FL, FR at a plurality of different timings; ) And the ratio of the slopes of the time series changes of the left and right rear wheels RL, RR and the brake torques T (j); (j = 3, 4) of the left and right rear wheels. Calculation result data is accumulated, and for each front wheel side and rear wheel side, for example, an average value of the accumulated data is calculated. These calculation results are the wheel load ratio of the left and right front wheels FL and FR and the wheel load ratio of the left and right rear wheels RL and RR, respectively.
Thus, the vehicle weight M is obtained by appropriately combining the ratio of the front wheel load WF and the rear wheel load WR, the wheel load ratio of the left and right front wheels FL and FR, and the wheel load ratio of the left and right rear wheels RL and RR. Each wheel load W is calculated by acting on.

Next, in step S05, the actual brake torque T of each wheel FL, FR, RL, RR is acquired.
Next, in step S06, the brake torque deviation (Tt-T) of each wheel FL, FR, RL, RR is calculated.

Next, in step S07, it is determined whether or not the selected ABS control mode is the pressure increasing mode.
If this determination is “NO”, the flow proceeds to step S 11 described later.
On the other hand, if the determination is “YES”, the flow proceeds to step S08.

In step S08, it is determined whether or not the brake torque deviation (Tt-T) of each wheel FL, FR, RL, RR is greater than or equal to a predetermined value.
If the determination result is “YES”, the process proceeds to step S09. In step S09, the first pressure increasing mode is set as the pressure increasing mode, and the process proceeds to step S11.
On the other hand, if this determination result is "YES", the process proceeds to step S10, and in this step S10, the second pressure increasing mode is set as the pressure increasing mode, and the process proceeds to step S11.
In step S11, for each wheel FL, FR, RL, RR, each solenoid valve 12, 15, 32, 35 is opened and closed according to the selected ABS control mode and brake torque deviation (Tt-T). The brake fluid pressure of each wheel cylinder 3a, 3b, 3c, 3d is controlled, and the process proceeds to return.

  As described above, according to the wheel load ratio detection device 10a according to the present embodiment, the ratio of wheel loads of the wheels (based on the outputs of the wheel speed sensors 45 and the brake torque sensors 46 mounted in advance in the vehicle) Wheel load ratio) can be detected, and the load (wheel load) of each wheel of the vehicle can be easily calculated from the wheel load ratio. As a result, it is possible to prevent the vehicle from having to secure a space for mounting a dedicated device for detecting each wheel load ratio and each wheel load, and to detect each wheel load ratio and each wheel load. Increase in cost can be suppressed.

In the above-described embodiment, the ratio of the front wheel load WF and the rear wheel load WR, the wheel load ratio of the left and right front wheels FL and FR, and the wheel load ratio of the left and right rear wheels RL and RR are calculated. However, the present invention is not limited to this. For example, the wheel load ratio of all wheels, that is, the wheel load ratio of (right) front wheel FR, (left) front wheel FL, (right) rear wheel RR, and (left) rear wheel RL. May be calculated in the form of a so-called connection ratio based on the time series change of each brake torque T (T (j); j = 1,..., 4).
In this case, the wheel load calculation region having a slip ratio that is low enough to prevent the anti-lock control (ABS control) from operating is, for example, the slower wheel speed of each of the left and right front wheels FL and FR that are drive wheels. In this region, the difference between the wheel speeds of the left and right rear wheels RL, RR, which are driven wheels, whichever is faster, is equal to or less than a predetermined value VW0 and is substantially zero. As a result, an appropriate wheel load calculation region can be set by performing low selection on the drive wheel side where slippage is likely to occur during braking and high selection on the driven wheel side where slippage is unlikely to occur.

  In the above-described embodiment, the wheel load calculation area is an area where the deviation between the front wheel speed and the rear wheel speed is equal to or less than the predetermined value VW0 and is substantially zero, but is not limited thereto. A region having a slip ratio that is low enough to prevent the anti-lock control (ABS control) from being activated may be used. It may be.

In the above-described embodiment, the anti-lock control device 10 performs the control process based on the detection signal output from each brake torque sensor 46. However, the present invention is not limited to this. For example, the anti-lock control device 10 described above with reference to FIG. As in the antilock control device 10 according to the first modification of the embodiment, for example, each brake torque sensor 46 is omitted, and each hydraulic pressure for detecting the brake hydraulic pressure of each wheel cylinder 3a, 3b, 3c, 3d is detected. Control processing may be performed based on the detection signal output from the sensor 61.
In the first modification, the ground point μ calculation unit 51 outputs, for example, from each hydraulic pressure sensor 61 in addition to the execution of the calculation processing according to the equations (1) to (5) in the above-described embodiment. The detection signal of the brake fluid pressure Pf of each wheel cylinder 3a, 3b, 3c, 3d, the brake cylinder diameter Ra of each wheel cylinder 3a, 3b, 3c, 3d, each brake pad friction coefficient Pμ, and the effective disk diameter Rb Based on the above, the brake torque T of each wheel described as shown in the following formula (11) is calculated.

In the above-described embodiment, the ground point μ computing unit 51 that calculates the ground point μ of each wheel (the friction coefficient at the ground point of each wheel) based on the detection signal output from each brake torque sensor 46 is provided. At the same time, the target torque calculation unit 57 calculates the target brake torque Tt of each wheel based on the detection signal of the brake torque T of each wheel output from each brake torque sensor 46. Each brake torque sensor 46 may be omitted as in the second modification of the above-described embodiment shown in FIG.
The antilock control device 10 according to the second modification includes, for example, a vehicle body deceleration calculation unit 62, a vehicle body speed calculation unit 63, an ideal slip ratio determination unit 64, a target wheel speed calculation unit 65, and a wheel speed deviation calculation. A unit 66, a target torque calculation unit 67, a torque deviation calculation unit 68, and a valve control unit 69 are provided.
And the detection signal output from each hydraulic pressure sensor 61 which detects the brake hydraulic pressure of each wheel cylinder 3a, 3b, 3c, 3d is input into the anti-lock control apparatus 10. FIG.

  The vehicle deceleration calculation unit 62 outputs from each wheel speed sensor 45 that detects each speed (each wheel speed VW (j); j = 1,..., 4) of the left and right front wheels FL, FR and rear wheels RL, RR. Based on the detected signal and a predetermined constant GR0FS, for example, the vehicle body deceleration GRDAT described in the following equation (12) (that is, the vehicle body deceleration for each of the left and right front wheels FL and FR and the rear wheels RL and RR). Speed GRDAT (j); j = 1,..., 4) is calculated.

For example, as shown in FIG. 10, in the above formula (12), the maximum speed GRV0 is the left and right at the time when the wheel acceleration ACL becomes zero in the pressure increasing mode (for example, time t0 shown in FIG. 10). Calculated from the speeds of the front wheels FL, FR and rear wheels RL, RR (each wheel speed VW (j); j = 1,..., 4) and each wheel speed VW (j) (j = 1,..., 4) Vehicle body speeds (respective vehicle body speeds VR0 (j); j = 1,..., 4).
The minimum speed GRV1 is the difference between the wheel speed VW and the vehicle body speed VR0 when the wheel acceleration ACL becomes zero (for example, time t1 shown in FIG. 10) after the maximum speed GRV0 is set in the pressure increasing mode. It is the minimum of them.
The time width ΔT is a time between times when the wheel acceleration ACL becomes zero in the pressure increasing mode (for example, between time t0 and time t1 shown in FIG. 10), and the wheel acceleration ACL is equal to or less than zero and ABS. This is the time between times when the flag value of the GR flag (F_GRFLAG) indicating that the pressure increasing mode is being executed as the control mode is switched from “0” to “1”.

The vehicle body speed calculation unit 63 calculates the vehicle body speed VR0 (k) based on, for example, the above formula (7) and the above formula (8).
For example, as shown in FIG. 11, the ideal slip ratio determination unit 64 detects the speeds of the left and right front wheels FL and FR and the rear wheels RL and RR (each wheel speed VW (j); j = 1,..., 4). For example, the slip ratio increases from a predetermined correspondence relationship set in advance with respect to the slip ratio calculated based on the detection signal output from each wheel speed sensor 45 and the friction coefficient at the contact point of each wheel. A coefficient of friction within a predetermined range (for example, within a range of 5 to 10%) is output as a peak μ.

  The target wheel speed calculator 65 outputs the vehicle speed VR0 output from the vehicle speed calculator 63 (that is, the vehicle speed VR0 (k) in the current calculation process) and the peak μ output from the ideal slip ratio determiner 64. Then, based on the predetermined constant a, the target wheel speed VWt described as shown in the formula (9) is calculated.

  The wheel speed deviation calculation unit 66 outputs each wheel speed VW output from each wheel speed sensor 45 (that is, each wheel speed VW (j) of the left and right front wheels FL, FR and rear wheels RL, RR; j = 1,..., A deviation (VWt−VW) between the detection signal of 4) and the target wheel speed VWt output from the target wheel speed calculation unit 65 is calculated.

  The target torque calculator 67 is based on the above formula (10) based on the deviation (VWt−VW) of each wheel output from the wheel speed deviation calculator 66, a predetermined conversion coefficient α, and a predetermined wheel inertia moment I. The target brake torque Tt of each wheel described as follows is calculated.

  The torque deviation calculator 68 detects the brake fluid pressure Pf of each wheel cylinder 3a, 3b, 3c, 3d output from each fluid pressure sensor 61, and the brake cylinder diameter of each wheel cylinder 3a, 3b, 3c, 3d. Based on Ra, each brake pad friction coefficient Pμ, and the disk effective diameter Rb, the brake torque T of each wheel described as shown in the above formula (11) is calculated. Then, a brake torque deviation (Tt−T) between the target brake torque Tt and the brake torque T of each wheel output from the target torque calculator 67 is calculated.

The valve control unit 69 controls the opening and closing of the electromagnetic valves 12, 15, 32, and 35 corresponding to the mode selected by the antilock control device 10.
Further, the valve control unit 69 sets the brake torque deviation (Tt−T) to zero based on the brake torque deviation (Tt−T) of each wheel output from the torque deviation calculation unit 68, for example. The brake fluid pressure of each wheel cylinder 3a, 3b, 3c, 3d is controlled by opening and closing the valves 12, 15, 32, 35.

  In particular, the valve control unit 69 selects the first pressure increase mode when the brake torque deviation (Tt-T) is equal to or greater than a predetermined value in the pressure increase mode, and the brake torque deviation (Tt-T) is less than the predetermined value. In this case, the second pressure increasing mode is selected.

It is a block diagram of the brake device which concerns on the anti-lock control apparatus which concerns on embodiment of this invention. It is a block diagram of the anti-lock control apparatus and wheel load ratio detection apparatus by this Embodiment. It is a figure which shows each physical quantity which concerns on the anti-lock control apparatus by this Embodiment. It is a figure which shows an example of the correspondence of the slip ratio and the longitudinal force which concern on the wheel load ratio detection apparatus by this Embodiment. It is a figure which shows an example of the time series change of the wheel speed which concerns on the wheel load ratio detection apparatus by this Embodiment, a wheel acceleration, and a brake torque. It is a figure which shows an example of the correspondence of the four-wheel brake torque which concerns on the wheel load ratio detection apparatus by this Embodiment, a wheel speed, and vehicle weight. It is a flowchart which shows operation | movement of the anti-lock control apparatus by this Embodiment. It is a block diagram of the anti-lock control apparatus and wheel load ratio detection apparatus which concern on the 1st modification of this Embodiment. It is a block diagram of the anti-lock control apparatus which concerns on the 2nd modification of this Embodiment. It is a graph which shows an example of each time change of each speed, wheel acceleration, ABS control mode, and GR flag in the anti-lock control device concerning the 2nd modification of this embodiment. It is a graph which shows an example of the correspondence of the slip ratio and friction coefficient in the anti-lock control apparatus which concerns on the 2nd modification of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anti-lock control apparatus 10a Wheel load ratio detection apparatus 10b Brake apparatus 45 Wheel speed sensor (speed state quantity detection means)
46 Brake torque sensor (braking torque detection means)
51 Grounding point μ calculation section (ratio calculation means, braking torque detection means)
61 Fluid pressure sensor (braking torque detection means)

Claims (1)

Speed state quantity detection means for detecting the speed state quantity of the vehicle;
Braking torque detection means for detecting the braking torque of each wheel of the vehicle;
A ratio of the braking torque of each wheel detected by the braking torque detecting means when the speed state quantity detected by the speed state quantity detecting means satisfies a predetermined condition is set as a wheel load ratio of the wheels. A wheel load ratio detection device comprising: a ratio calculation means.

Images