JPH0780446B2 - Lock prevention adjustment method and lock prevention device for implementing this method - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention is directed to the front axle or rear axle load due to the significant increase in front and rear axle loads that occur at high speeds from aerodynamic configurations of road vehicles designed for high speeds. Comparative quantity Kv = Xv · Zv + Y · λv or Kh = Xh for the axle, formed as the sum of the wheel circumference deceleration Zv or Zh of each wheel of the rear axle and the weighted value of the braking slip λv or λh with respect to the reference speed When Zh + Yλh exceeds the limit value for the axle, which is compatible with the stable dynamic behavior of the vehicle at large values of wheel deceleration, the braking pressure of the wheel brakes should be reduced at the wheel that needs adjustment. Start the operation of the lock prevention adjustment device,
The weighting factors Xv, Xh and Y are standardized so that Xv (Zmaxv + ΔZo) = 1 or Xh (Zmaxh + ΔZo) = 1 and Y · λmaxv = 1 or Y · λmaxh = 1 is established, and the aerodynamic force is Zmaxv or Zmaxb. The maximum wheel circumference deceleration of the front or rear axle with the maximum possible vehicle deceleration is taken into consideration, λmaxv or λmaxh is the maximum allowable braking slip value of the front or rear axle, and ΔZo is approximately It shows a safe value with a value of 0.3, so that Zmaxv and Zmaxh satisfy the following equation, In these equations, the lock limits Zblv and Zblh are given by , Μv shows the friction coefficient of the front axle, μh shows the friction coefficient of the rear axle, χ shows the load ratio of the rear axle, χ shows the height of the center of gravity with respect to the axle distance, and φ shows the weight of the vehicle. The rear axle braking force ratio is indicated, K _vA is the positive or negative lift coefficient of the front axle, K _HA is the positive or negative lift coefficient of the rear axle, K _w is the air resistance coefficient, and G is the vehicle BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock prevention adjusting method and a lock prevention apparatus for carrying out this method.

[Conventional technology]

In such a lock prevention adjusting method, how to obtain the maximum value Zmaxv or Zmaxh of the wheel deceleration of the front axle or the rear axle and the numerical value of the lock limit Zblv or Zblh, etc.
“Berechnung und Rekonstructi” by M. Burckhardt et.al.
on des Bremsverhaltens von PKW ", (1988, ISBN3-885
50-025-6).

A locking device which operates in this way is also known from German Utility Model 6925179.2.

In this known anti-lock device, the wheel circumferential deceleration Zv or Zh of each wheel and the sum Xv, hZv, h of the values weighted by the weighting factor Xv or Xh of the braking slip λ with respect to the reference speed are used.
+ Y · λv, h = Kv, h as a comparison quantity (subscript v
Represents the front axle and h represents the rear axle) exceeds the operating limit, the braking pressure reduction phase in the wheel brake of the wheel which is prone to locking is initiated. This operating limit is standardized to 1 for practical reasons, that is to say that the adjusting device is actuated only by an excessively large braking slip and the wheel does not undergo a significant deceleration or the wheel does not undergo a significant braking slip. When decelerating to the extent equivalent to the lock limit, the product Y · λv, h
Alternatively, the weighting factors Xv, h and Y are set so that the products Xv, h · Zv, h each have a value of 1.

The weighting numbers Xv, h and Y are defined as frequency-specific constants both in the publications mentioned above and in the anti-locking device which is a further development of this device, and a dynamic stable braking behavior is obtained by matching these amounts. Which gives a typical 0 for the sum.
A safety value .DELTA.Zo with a value of 3 is added to start the adjustment at the wheel which takes too much deceleration or braking slip before the rock limit is reached.

In a production vehicle with aerodynamic behavior that reaches a maximum speed of approx. 200 km / h and is almost neutral to speed, this generation of comparative quantities leads to road conditions and tires even at the maximum vehicle speed in anti-lock adjustment operation. Well suited to obtain the maximum vehicle deceleration possible due to performance, but may have values of 350 km / h or more in competitive vehicles, with aerodynamic aids that provide a significant increase in axle load at high vehicle speeds Not suitable for racing vehicles. In this case, the axle load acts on the front and rear axles with different strengths, and the increase in speed-related aerodynamic axle load is such that in modern competition vehicles, the axle load on the rear axle is approximately twice that on the front axle. It also becomes a value.

A competition vehicle with an anti-lock device of the type first mentioned experimentally has a braking pressure distribution control that operates in relation to the axle load to enable load-appropriate front-rear-axle braking force distribution. It has been found that, even when the system is present, it has a significantly worse vehicle deceleration than a properly designed but competitive vehicle without a locking device.

[Problems to be Solved by the Invention]

The object of the present invention is therefore to improve the antilocking adjustment method of the type mentioned at the beginning, to enable a controlled braking with a large vehicle deceleration even at maximum vehicle speed and to be suitable for implementing this method. It is to provide a device.

[Means for Solving the Problems]

In order to solve this problem, according to the method of the present invention, Xmax (Xv, Xh) and Under the quadratic condition, the weighting factor is reduced according to the following equation X = Xo−b · v in relation to the vehicle speed v, and the larger value of Xv and Xh at max (Xv, Xh) , Min is the minimum value, and Xo and b are positive constants (Xo >> b) smaller than 1.

〔The invention's effect〕

In this way, a single weighting factor X represented by the formula Xo-b.v is formed for the front and rear axles, and as a result, the comparative quantity Kv to be set for the operating limit value of the anti-lock adjustment method.
And Kh, a wheel circumference deceleration weighting that decreases with increasing vehicle speed v is obtained, so that the wheel to be adjusted is at least nearly optimal under the respective wheel conditions for braking force transmission. When taking the deceleration, the adjusting device is activated, i.e. an adjustment is made which allows the maximum possible vehicle deceleration to be used depending on the situation despite the stable braking behavior of the vehicle.

The formation of the weighting factor X, which has a linear relationship with the vehicle speed v, can be carried out in a short time without any problems by an ordinary computer and is therefore very well suited for the rapid online processing of speed information data. Of the vehicle, which is particularly advantageous for the competitive driving of competitive vehicles.

[Embodiment]

A device suitable for carrying out the method according to the invention is claim 2.
4 through 4.

In the lock prevention device according to the second aspect, it is possible to supply the braking pressure to the wheel brakes in a speed-related manner in response to the changing axle load, and when the lock prevention device operates, a small rear axle is provided. The anti-lock adjustment is facilitated by a switching back to a dynamically stable braking force distribution with a load ratio.

The features of claims 3 and 4 enable a technically simple realization of the lock prevention device according to claim 2.

〔Example〕

A lock prevention device according to the present invention and its function will be described below with reference to the drawings.

The anti-lock device, which is generally designated by 10 in FIG. 1, is considered for road vehicles, especially competition vehicles, which enable extremely large braking. In FIG. 1, this vehicle is a braking pressure generator.
11, rear wheel brakes 12 and 13, braking pressure adjusting valves 14 to 17 electrically attached to the rear wheel brakes and electrically actuable, a return pump 18 that can be electrically driven, and a lock prevention device 10. Represented by an electronic controller, generally indicated at 19, the potential controller produces the signals necessary to control the electrically actuatable elements in the proper sequence and combination for adjustment.

It is assumed that the vehicle braking system is configured as a hydraulic two-circuit braking system with braking circuits on the front and rear axles.

FIG. 1 shows a wheel brake, a braking pressure regulating valve, and an electronic control unit belonging to the front axle braking circuit I, which is represented only by a pressure outlet 21 provided for the front axle braking circuit I of the braking pressure generator 11. The functional parts of 19 are not shown for simplicity of illustration.

In the embodiment chosen for further explanation, the anti-lock device operates according to the so-called return principle, and during the braking pressure reduction phase of the anti-lock adjustment, the braking liquid discharged from the wheel brakes 12 and 13 is By means of the return pump 18 of the axle braking circuit II, it is returned to the main braking conduit 22, i.e. to the output pressure space 23 of the braking pressure generating device 11 belonging to this braking circuit II, this braking pressure generation assuming a tandem parent cylinder of known construction. Device 11
Is assumed to be operable by a brake pedal 24 via a hydraulic or pneumatic braking booster 26 as is conventional. The wheel brakes 12 and 13 of the rear axle braking circuit II are designed as four-cylinder fixed caliper brakes and have two wheel cylinder pairs 27, 28 and 29, 31 respectively. One wheel cylinder pair 27 or 28 of the wheel brake 12 for the one rear wheel, respectively, is connected to the wheel cylinder pair 29 or 31 of the wheel brake 13 for the other rear wheel by a braking conduit branch 32 or 33. To form a partial braking circuit II 'or II ".

One partial braking circuit II ′, which includes both wheel cylinder pairs 27 and 29 of both rear wheel brakes 12 and 13, is connected via a braking pressure regulating valve 14 configured as a two-port two-position switching solenoid valve to the rear The initial position 0 of this braking pressure regulating valve, which is connected to the main braking conduit 22 of the axle braking circuit II, is the conducting position and its excited position I is the shut-off position. The other partial braking circuit
II 'is likewise connected to the main braking line 22 of the rear axle braking circuit II via a braking pressure regulating valve 15 which is likewise configured as a 2-port 2-position switching solenoid valve, the initial position of which is the braking pressure regulating valve. 0 is the cutoff position, and the excited position I is the conduction position. Both of these braking pressure control valves 14 and 15
Is normally used as an inlet valve in braking operations that are not subject to anti-lock adjustment and in regulated braking operations, through which braking pressure is established in the wheel brakes 12 and 13 or anti-lock adjustment is performed. The braking pressure re-establishment phase is controlled. The partial braking circuits II 'and II "are connected to the inlet side of the return pump 18 or to its inlet check valve 34 via another two braking pressure regulating valves 16 and 17, respectively. The pressure control valves 16 and 17 are also 2
It is configured as a port 2 position switching solenoid valve, whose initial position 0 is the shut-off position and their excited position I is the conduction position. Their function in the anti-lock adjustment operation is the control of the braking pressure reduction stage in the rear wheel brakes 12 and 13.

In the embodiment shown, both braking pressure regulating valves 16 and 17 as outlet valves are always controlled together. In the hydraulic system shown by reference numeral 36, the circuit device and the hydraulic device shown only for the rear axle, the lock prevention device 10 operating with the same phase adjustment in the rear wheel brakes 12 and 13, that is, the braking pressure reduction in both the rear wheel brakes. For the lock prevention device in which the steps of holding the braking pressure and reestablishing the braking pressure are performed in the same direction at the same time, the front wheel brake (not shown) is subjected to the individual wheel adjustment which can also operate in the opposite phase, that is, It is assumed that the front wheel brakes reduce the braking pressure and the other front wheel brakes establish the braking pressure. The construction of the part of the hydraulic device 36 belonging to the front axle braking circuit I is known in this respect and is therefore not described here. A processing circuit 37 provided in the range of the electronic control unit 19 is also known, and from the processing of the output signal of the rotation speed sensor attached to the wheel, a signal characterizing the vehicle speed, the vehicle acceleration, the vehicle deceleration and the braking slip is generated, From the subsequent processing and logical combination of these signals, the control signals necessary for the control suitable for the regulation of the braking pressure regulating valves 14 to 17 and the return pump 18 are obtained.

The electronic control unit 19 comprises a computer, indicated generally at 38, which is continuously generated by the processing circuit 37 to determine the wheel circumferential velocity v, the braking slip λh relating to the reference speed generated by the processing circuit 37 according to known standards and algorithms. , And a comparison containing information about the wheel circumference deceleration Zh and the wheel circumference acceleration of the wheels to be controlled individually or together is provided as an input to the calculator 38. From this online processing of v, λ and Z inputs,
The calculator 38 forms the comparison quantity Kh according to the following equation.

Kh = Xh · Zh + Y · λh (1) where the coefficient Xh is given by the equation Xh · (Zmaxh + ΔZo) = 1 (2), where Zmaxh is the maximum braking obtained for the vehicle weight G on a dry and non-slip road. Shows,
Zo is a safe value with a value of about 0.3, and the coefficient Y is determined by the formula Y · λmaxh = 1 (3), where λmaxh allows a still stable dynamic behavior of the vehicle and has a typical value of about 0.2. Represents the maximum braking slip of the rear axle having a specific value, Zh represents the wheel circumferential deceleration of the rear wheel, and λh represents the braking slip.

Therefore, the comparison amount Kh is a weighted sum of the wheel circumferential deceleration including the safety value and the braking slip and the braking slip. When the comparison quantity Kh reaches or exceeds a reference value 1, which can be referred to as the standardized operating limit value of the anti-lock adjustment, the first comparator 39 of the electronic control unit 19 produces a (high level) output. The signal controls the outlet valves 16 and 17 of the hydraulic device 36 to the conductive position I.

The control of the braking pressure reduction phase mentioned above of the anti-lock adjustment is the control of a known anti-lock device, the comparison quantity being compared with the operating limit value is likewise formed as a weighted sum of the wheel deceleration and the braking slip. To be done.

Unlike the known anti-lock device having a constant weighting coefficient, the weighting factor Xh in the anti-lock device 10 is formed in relation to speed by the following equation.

Xh = Xoh−b · v (4) Here, Xoh and b are positive constants, which are about 0.6 and
Has a typical value of 0.005.

In order to clarify this function of the calculator 38, a circuit 41 for generating a weighting coefficient Xh from the speed input v by the equation (4),
The calculator 38 is provided with an output circuit 42 that forms a comparison amount Kh from the information of slippage and deceleration in consideration of the weighting coefficient Xh that is variable according to the speed, using the equation (1).

Furthermore, the electronic control unit 19 includes a second comparator 43, which controls the vehicle speed.
When v _F becomes larger due to the speed limit value v _S of, for example, 100 km / h, the comparator 43 compares the output signal of the processing circuit 37 representing the vehicle speed v _F with the reference signal corresponding to the speed limit value v _S. , (High level) to generate the output signal.

The output signal of the speed comparator 43 is supplied to the non-inverting input terminal 44 of the two-input AND element 46, and the second inverting input terminal of the AND element is connected to the output terminal of the first comparator 39. This AND element 4
A (high level) output signal of 6 switches the braking pressure regulating valve 15 which, as an inlet valve, belongs to the partial braking circuit II "and shuts off at the initial position 0 to the energized conduction position I.

As a result, at the speed limit value v _S or more, the second partial braking circuit II ″ of the rear axle braking circuit II continues to operate.
It is connected to II 'and thus provides a braking force distribution which increases the proportion of the rear axle part. This change in the braking force distribution rate is not accompanied by a reduction in the dynamic stability of the vehicle. This is because at high vehicle speeds, aerodynamic forces acting on the vehicle increase the stronger axle load on the rear axle than on the front axle.

When the locking device 10 acts on the rear axle to reduce the braking pressure, that is, when the output signal of the first comparator 39 goes to a high signal level, the output signal of the AND element 46 disappears, which causes partial braking. Due to the return of the inlet valve 15 belonging to the circuit II ″ to the initial position 0, the connectable partial braking circuit II ′
From the main braking conduit 22 of the rear axle braking circuit II,
Of the braking conduit branch supplying pressure to the partial braking circuit II "of the.

The anti-lock device 10 described thus far works at high running speeds in combination with fixedly matched different values of the braking force distribution or with braking devices which can be continuously set to different values of the braking force distribution. In order to obtain as large a vehicle deceleration as possible in consideration of the aerodynamic force
Unlike the conventional anti-lock device, the anti-lock device 10 is configured such that the pressure reduction operation limit value of the anti-lock adjustment is obtained only when the vehicle speed is large and the wheel circumferential deceleration is large.

In the illustrated embodiment, this is done by reducing the speed-related weighting factor Xh according to equation (4) for the rear wheel brakes 12 and 13, which causes the wheel circumference deceleration Zh to be compared by the comparison quantity Xh. This comparative amount is compared with a reference amount which is standardized to a value of 1 in the examples.

The same applies to the front wheel brake, and the following equation similar to equations (1) to (4) holds.

Kv = Xv · Zv + Y · λv (1 ′) Xv = 1 / (Zmaxv + ΔZo) (2 ′) Y = 1 / λmaxv (3 ′) Xv = Xov−b · v (4 ′) Calculator 38 and comparator 39
The parts of the electronic control unit 19 required in Figure 3 are not shown for simplicity.

The constants Xoh and Xov and b, which are important for the formation of the weighting factors Xh and Xv according to equations (4) and (4 ′), are determined, for example, by experiments with a roller test bench in the wind tunnel,
Alternatively, the maximum braking Zmaxh and Zmaxv obtained by the following equations (5) and (5 ') in consideration of the aerodynamic force can be calculated by using the maximum braking Zmaxh and Zmaxv in the equations (3) and (3'). it can.

For the rear axle Against the front axle In formula (5), Zblh indicates the lock limit of the rear wheel given by the following formula, In equation (5 '), Zblv represents the front wheel lock limit given by the following equation.

The quantities shown in equations (5), (5 '), (6) and (6') are defined as follows.

μh is the friction coefficient of the rear axle, μv is the friction coefficient of the front axle, G is the vehicle weight represented by N, ψ is the rear axle load ratio with respect to the vehicle weight G, χ is the height of the center of gravity with respect to the center distance, and φ is the vehicle weight G Rear axle braking force ratio, K _vA is the front axle lift coefficient, K _HA is the rear axle lift coefficient, Kw is the air resistance coefficient expressed by Ns ⁻² m ⁻² , and v is the speed expressed by ms ⁻¹ .

How these formulas are derived is explained in "Berech
nungund Rekonstruktion des Bremsverhaltens von PK
Since it is described in detail in W ", the description thereof is omitted.

Φ = 0.4, K _vA = -1 χ = 0.14, K _HA = -2 ψ = 0.6, Kw = 0.6 G = 10000N Friction coefficient μv and μh for front and rear axles for a competition vehicle with the following data Is 1.5
It has the same value of the calculated safety value Zo is the weighting coefficient Xh and Xv assuming to have a value of 0.3 (5) and (5 '), with respect to 0 to the speed range of 70 ms ^-1 The values summarized in Table I are obtained.

As can be seen from the graph in this table shown in FIG. 2, both the broken line Xh curve 48 and the dashed line Xv curve 49 are shown in equations (4) and (4) for a typical competition vehicle with the above data. As shown in general form by (4 '), it is very well followed and fully approximated by a straight line 51 satisfying the following equation.

X = 0.6−0.005v (7) The quadratic condition for this approximation, represented by equation (7), must always be greater than the larger of the values Xv or Xh, ie Xmax ( Xv, Xh) holds, and both intersect in the area between the curve given by the above equation and the straight line given by equation (7) or equation (4) or (4 '), that is, v = 20. Curve 48
And 49, the area sandwiched between the upper curved portion and the straight line 51 must be the minimum, that is, Is established.

The inertia of the wheel is also taken into account for the calculation of the weighting factors Xv and Xh, in which case the following equations hold instead of equations (4) and (4 ').

The same can be said of the case.

From the calculation of these equations (8) and (8 '), the values of Xv and Xh, which are shown in Table 2 in relation to the velocity, are obtained.
Is only slightly different from the value of.

The curves corresponding to the values in Table 2 are not shown in FIG. 2 for the sake of clarity.

[Brief description of drawings]

FIG. 1 is a block diagram of a preferred embodiment of the lock prevention device according to the present invention, and FIG. 2 is a diagram for explaining the operation of the lock prevention device according to FIG. 10 …… Lock prevention device, 12,13 …… Rear wheel brake, 19 ……
Electronic control unit, 39, 43 ... Comparator.

Claims (4)

[Claims] 1. Wheel peripheral speeds Zv or Zh of the respective wheels of the front or rear axle due to the significant increase in front and rear axle loads that occur at high speeds due to the aerodynamic configuration of road vehicles designed for high speeds. And a comparison quantity Kv = Xv · Zv + Y · λv or Kh = Xh · Zh + Yλh formed as the sum of the weighted values of the braking slip λv or λh with respect to the reference speed, the vehicle stability at large values of wheel deceleration. When the limit value related to the axle, which is compatible with various dynamic behaviors, is exceeded, the operation of the anti-lock adjustment device is started so as to reduce the braking pressure of the wheel brake in the wheel that requires adjustment,
The weighting factors Xv, Xh and Y are standardized so that Xv (Zmaxv + ΔZo) = 1 or Xh (Zmaxh + ΔZo) = 1 and Y · λmaxv = 1 or Y · λmaxh = 1 holds, and the aerodynamic force is Zmaxv or Zmaxh. The maximum wheel circumference deceleration of the front or rear axle with the maximum possible vehicle deceleration is taken into consideration, λmaxv or λmaxh is the maximum allowable braking slip value of the front or rear axle, and ΔZo is approximately It shows a safe value with a value of 0.3, so that Zmaxv and Zmaxh satisfy the following equation, In these equations, the lock limits Zblv and Zblh are given by , Μv is the friction coefficient of the front axle, μh is the friction coefficient of the rear axle, ψ is the load ratio of the rear axle, χ is the height of the center of gravity with respect to the axle distance, and φ is the weight of the vehicle. The rear axle braking force ratio is indicated, K _vA is the positive or negative lift coefficient of the front axle, K _HA is the positive or negative lift coefficient of the rear axle, K _w is the air resistance coefficient, and G is the vehicle In the lock prevention adjustment method showing weight, Xmax (Xv, Xh) and Under the quadratic condition, the weighting factor is reduced according to the following equation X = Xo−b · v in relation to the vehicle speed v, and the larger value of Xv and Xh at max (Xv, Xh) And a minimum value is indicated by min, and a positive constant (Xo >> b) smaller than 1 is indicated by Xo and b. 2. A braking system of a vehicle in which the braking circuit is divided into a front axle braking circuit and a rear axle braking circuit is switchable between at least two braking force distribution values corresponding to different fixed alignments. In this case, the electronic control unit (19) of the lock prevention device (10) generates a speed comparator (43) that outputs an output signal for switching to a braking force distribution having a large rear axle braking force ratio when the speed limit value is exceeded. And a comparator (39) for comparing the comparison amount Kh with an operation limit value. When the comparison amount Kh reaches the reference amount and the adjusting device operates so as to perform the pressure reduction step, the comparator (39) An anti-lock device for carrying out the method according to claim 1, characterized in that the braking device is returned to a braking force distribution with a rear axle braking force ratio which is small. 3. The rear wheel brake (12, 13) is configured as a four-cylinder brake, and the cylinder pair (27, 28) of one rear wheel brake (12) is the other rear wheel brake (13). Cylinder pair (29,
31) together with the rear axle braking circuit (II) partial braking circuit (I
I ', II ″), one of these partial braking circuits is cut off by the valve (17) to the braking pressure generator (11) below the speed limit value v _S , and this valve (17) is compared for speed comparison. Device according to claim 2, characterized in that it is controlled to the open position by the output signal of the device (43). 4. A device according to claim 3, characterized in that a parent cylinder is provided which can switch the braking pressure distribution in order to switch the braking force distribution.