JPH03153455A - Lock prevention and adjustment and device for preventing lock - Google Patents

Abstract

PURPOSE: To attain braking regulated by large vehicle deceleration even at the maximum vehicle speed by performing weighting processing of wheel circumferential deceleration reduced with the increase of vehicle speed in an anti-lock device ideal for a racing vehicle. CONSTITUTION: This device supplies braking force generated by a braking force generating device 11, to rear wheel brakes 12, 13 through braking pressure regulating valves 14-17 and draws out braking pressure in the rear wheel brakes 12, 13 by a return pump 13, and the respective regulating valves 14-17 are controlled by an electronic control unit 19. In this case, the electronic control unit 19 is provided with a computer 38 inputting the compared result including information continuously generated by a processing circuit 37 on a brake slip caused by wheel circumferential speed or the like, and wheel circumferential acceleration/deceleration. The comparative quantity to be the weighted sum of wheel circumferential deceleration and brake slip is computed, and a weighting coefficient is obtained in relation to vehicle speed. A control signal is outputted according to the compared result of the comparative quantity and a critical value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] This invention relates to the significant increase in front and rear axle loads that result at high speeds from the aerodynamic configuration of road vehicles, especially competition vehicles, designed for high speeds. The comparison quantity Xv==Xv・Zv−y・personv or Kh ;Xh-Zh
- If Yλh exceeds the limit value for the axle, which is compatible with stable dynamic behavior of the vehicle at large values of wheel deceleration, the braking pressure of the vehicle brake system is reduced at the wheel that requires adjustment. The anti-lock adjustment device starts operating as follows, and the weighting coefficient XV! By unifying Xh and Y with m, we get Xv (Zmaxv+ΔZo);l or Xh (Zm
axh±ΔZo)=1 and Y-person maxv==1 or Y
−λmaxh=1, and Zmaxv or Ztraxh indicates the maximum value of the wheel circumferential deceleration with the maximum possible vehicle deceleration considering aerodynamic forces, and λmaxv or λ
maxh indicates the maximum allowable brake slip value, and ΔzO
The present invention relates to an anti-lock adjustment method which exhibits a safety value with a value of approximately 0.3, and to an anti-lock device for implementing this method.

[Conventional technology]

An anti-locking device operating in this way is the subject of German Utility Model No. 6925179.2.

In this known lock prevention device, the wheel circumferential deceleration Zv or Zh of each wheel and the braking slip λ with respect to the reference speed are
The sum of values X weighted by the weighting coefficient Xv or xh
If v+h-Zv,b+Y-Av.h exceeds the operating limit value, a brake pressure reduction phase is initiated in the wheel brake of the wheel with a tendency to lock. This operating limit value has been standardized to 1 for practical reasons, i.e. the regulating device is activated only with excessive brake slip and the wheels do not undergo significant deceleration, or the wheels lock without significant brake slip. When decelerating to an extent equivalent to , the weighting coefficients Xv, h and Y are set so that the product Y-λv-h or the product Xv, h·Zv, h each has a value of l.

The weighting coefficients Xv, h, and Y are defined as constant quantities proportional to frequency in both the above-mentioned publication and the anti-lock device developed from this device, and the matching of these quantities results in dynamically stable braking behavior. is obtained, and to said sum a safety value ΔZo with a typical value of 0.3 is added to initiate adjustment at wheels that experience excessive deceleration or brake slip before the locking limit is reached. .

Such an occurrence in Comparison C1 can be explained by the fact that in a mass-produced vehicle that reaches a maximum speed of about 200 km/h and has an aerodynamic behavior that is almost neutral with respect to speed, even at the maximum vehicle speed in anti-lock adjustment operation, road conditions and Aerodynamic aids that are well suited to obtain the maximum possible vehicle deceleration due to tire performance, but that carry out a significant increase in axle loading at high vehicle speeds, which can take on values of 350+/h or more in competition vehicles. Not suitable for competitive vehicles with means. In this case the axle loads act with different strengths on the front and rear axles, and the increase in speed-related aerodynamic axle loads is approximately twice as much on the rear axle as on the front axle in modern competition vehicles. It is also the value of

Competition vehicles experimentally equipped with anti-lock devices of the first type listed have brake pressure distribution controls that operate in relation to the axle load to allow load-appropriate front-axle-rear axle brake force distribution. Even when the device is present, it has been found that the vehicle decelerates significantly worse than a properly designed competitive vehicle without the anti-lock device.

[Problem to be solved by the invention]

It is therefore an object of the present invention to improve an anti-lock adjustment method of the first type to enable coordinated braking with large vehicle decelerations even at maximum vehicle speeds and to provide an apparatus suitable for carrying out this method. The goal is to provide the following.

[Means to solve the problem]

According to the method of the present invention to solve this problem, X>wax (Xv+Xh) and max 5 (X-wax (Xv+
11 under the quadratic condition of Formed by the formula, pv indicates the M friction coefficient of the front axle, μh indicates the friction coefficient of the rear small axle, φ indicates the load ratio of the rear axle, χ indicates the height of the center of gravity regarding the lead plate between the axles, φ indicates the rear axle braking force ratio with respect to vehicle weight, and KvA
indicates the positive or negative lift coefficient of the front axle, KHA"C indicates the positive or negative lift coefficient of the rear axle, Kv indicates the drag coefficient, and G indicates the vehicle weight.

As an apparatus for implementing this method, a braking force distribution value of a vehicle whose braking circuit is divided into a front axle braking circuit and a rear axle braking circuit and a rear axle braking circuit is provided. The electronic control unit of the anti-lock device can switch between a speed comparator and a speed comparator corresponding to different fixed alignments to switch over to a brake force distribution with a higher rear axle force ratio when the speed limit value is exceeded. , a comparator for comparing the comparison flKh with the operating limit value, which comparator determines the small rear axle braking force side when the comparison ff1Kh reaches a reference quantity and the regulating device operates to carry out a pressure reduction step. Return the braking system to the corresponding braking force distribution.

〔Effect of the invention〕

In this way a uniform weighting factor X is formed for the front axle and the rear axle, and when forming the comparisons JlKv and Kh to be set for the operating limits of the anti-lock regulating device, the wheel circumference decreases with increasing vehicle speed. By resulting in a speed weighting, it is possible to ensure that the wheels undergoing adjustment have at least approximately the optimal deceleration under the respective wheel conditions for braking force transmission, i.e. despite a stable braking behavior of the vehicle. It allows the use of the maximum possible deceleration depending on the situation, which is considered a major advantage.

The formation of the weighting factor X, which corresponds to a linear relationship of speed, is very well suited to the rapid online processing of speed information data and allows a fast reaction of the anti-lock device, which is particularly important for competitive driving.

〔Example〕

The anti-locking device according to the invention and its function will be explained below with reference to the drawings.

The anti-locking device, generally designated 10 in FIG. 1, is intended for road vehicles, especially competition vehicles, which permit extremely high braking, and in FIG. The entirety of the rear wheel brakes 12 and 13, the electrically energizable brake pressure regulating valves 14 to 17 attached to these rear wheel brakes, the electrically drivable return pump 18, and the lock prevention bag Hto. It is represented by an electronic control unit indicated at 19, which generates the signals necessary to control the electrically actuatable elements in the sequence and combination suitable for adjustment.

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

FIG. 1 shows the wheel brakes, brake pressure regulating valves, and electronic control equipment belonging to the front axle brake circuit I, which are represented only by the pressure outlet 21 provided for the front axle brake circuit 1 of the brake pressure generating device 11. The functional parts of @19 are not shown for simplicity of illustration.

In the embodiment chosen for further illustration, the anti-lock device operates according to the so-called return principle, so that during the braking pressure reduction phase of the anti-lock adjustment, the brake fluid discharged from the wheel brakes 12 and 13 is transferred to the rear axle brake. Return pump 1 of circuit I
8 to the main brake conduit 22, i.e. to the output pressure air rIJJ23 of the brake pressure generator 11 local to this brake circuit 1, this brake pressure generator II, assuming a known tandem parent cylinder of 81 TB, It is assumed that the brake pedal 24 can be operated via a hydraulic or pneumatic brake booster 26 as shown in FIG. The wheel brakes 12 and 13 of the rear axle brake circuit I are configured as four-cylinder fixed caliper brakes, each with two wheel cylinder pairs 2
It has 7.28 and 29.31. One pair of wheel cylinders 27 in each case of the wheel brake 12 of one, i.e. the left rear wheel.
or 28 is connected by a brake conduit branch 32 or 33 to the wheel cylinder pair 29 or 31 of the wheel brake 13 of the other, ie the right rear wheel, to form a partial brake circuit ■' or 111.

One partial braking circuit ■', which includes both axle cylinder pairs 27 and 29 of both rear wheel brakes 8! 12 and 13, is operated via a braking pressure regulating valve 14 configured as a 2-port 2-position switching @ solenoid valve. , is connected to the main brake conduit 22 of the rear axle brake circuit 1, and the initial auxiliary position O of this brake pressure regulating valve is the conduction position, and its energized position ff1I is the cutoff position.

The other partial braking circuit 1' is likewise connected to the main m conduit 22 of the rear axle braking circuit I via a braking pressure regulating valve 15, which is likewise constructed as a two-boat two-position switching solenoid valve, and is connected to the main m-conduit 22 of the rear axle braking circuit I. The initial position @0 of the pressure regulating valve is the cutoff position,
The excited position 11fflI is the conducting position. These two brake pressure regulating valves 14 and I5 are used as inlet valves in normal braking operation, i.e. without anti-lock regulation and in HIM braking operation, and via these valves the brake pressure at the wheel brakes 12 and 13 is Establishment is performed or the brake pressure re-establishment phase of the anti-lock adjustment is controlled. The partial brake circuits 1' and 1'' are connected via one of two further brake pressure regulating valves 16 and 17 respectively to the inlet side of the return pump 18 or to its inlet check valve 34. The dynamic pressure regulating valves 16 and 17 are similarly constructed as two-boat two-position switching solenoid valves, and their initial positions O are respectively cutoff positions, and their energized positions I are conductive positions.Lock prevention adjustment operation Their function in is the control of the braking pressure reduction phase in the rear brakes 12 and 13.

In the illustrated embodiment, the two brake pressure regulating valves 16 and 17 as outlet valves are always controlled together. In the planting, the circuit device il, and the hydraulic system shown as 36 as a whole, which have been explained only with respect to the rear axle, the rear brakes 12 and 13 are in the same phase! l! In contrast to the anti-lock device lO1, which operates at the same time, that is, the anti-lock device in which the steps of reducing the braking pressure, maintaining the braking pressure, and re-establishing the braking pressure in both rear brakes are carried out simultaneously in the same direction, the front brake a (not shown) assumes that an individual wheel adjustment is provided which can also operate in opposite phases, ie the braking pressure is reduced on one front brake and the braking pressure is established on the other front brake.

The configuration in this regard of the parts of the hydraulic system 36 belonging to the front axle braking circuit I is known and will therefore not be described here.

A processing circuit 37 provided in the area of the electronic control unit 19 is also known, which generates signals characterizing the vehicle speed, vehicle acceleration, vehicle deceleration and braking slip from the processing of the output signals of rotational speed sensors associated with the wheels. The subsequent processing and logical combination of these signals results in the necessary control signals for suitable regulation of the brake pressure regulating valves 14 to 17 and the return pump 18.

The electronic control unit 119 includes a computer indicated generally by 38,
Continuously generated by the processing circuit 37, the wheel peripheral speed v1
A comparison containing information about the brake slip Xh1 and the circumferential wheel deceleration Zh and the circumferential acceleration of the wheels to be adjusted individually or together, generated by the processing circuit 37 according to known standards and algorithms, is provided as input. It is supplied to the computer 38. From this online processing of the inputs of V, λ, and 2, the calculator 38 calculates a comparison 11'l using the following formula.
Forms Kh.

Kh = Xh-Zb +Y-λh (1
) where the coefficient xh is given by the formula % (2) where Zmax indicates the maximum braking obtainable for the vehicle type Hc on a dry and non-slip road and Zo is the safety coefficient with a value of approximately 0.3. and the coefficient Y is determined by the formula % (3) where λmaxh is the maximum of the rear axle that allows a still stable dynamic behavior of the vehicle and has a typical value of about 0.2 Zh indicates the wheel circumferential acceleration of the rear wheel, and Xh indicates the brake slippage.

The comparison rdKh is therefore a weighted sum of the wheel circumferential deceleration and the brake slip, including the safety value and the brake slip. If the comparison quantity Kh reaches or exceeds the 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 generates a (high level) output The signal causes the outlet valves 16 and 1 of the hydraulic device 36 to
7 is controlled to the conducting position ■.

The control of the brake pressure reduction phase described so far in the anti-lock adjustment is the basis of known anti-lock devices, and the comparison variable that is compared with the operating limit value is likewise formed as a weighted sum of wheel deceleration and brake slip. be done.

Unlike known anti-lock devices in which the weighting factor has a constant value, an anti-lock device! Weighting coefficient xh at 0
is formed in relation to the speed by the following equation:

Xh = Xoh-try (4)
Here, Xoh and b are positive constants, each approximately 0.
6 and 0.005.

To demonstrate this functionality of the calculator 38, the speed input V
A circuit 4 that generates a weighting coefficient xh from equation (4)
1, and an output circuit 42 that forms a comparison amount Kh from the slip and deceleration information using equation (1) in consideration of a weighting coefficient xh that is variable depending on the speed.

Furthermore, the t-child control device ra19 includes a second comparator 43 which, when the vehicle speed Vp increases by a speed limit value vs of, for example, 1100 k/h, outputs the output signal of the processing circuit vI37 representing the vehicle speed vF. A (high level) output signal is generated from the comparison of VS and a reference signal corresponding to the speed limit value vs.

The output signal of the speed comparator 43 is fed to a non-inverting input 44 of a two-input AND element 46, the second inverting input of which is connected to the output of the first comparator 39.

Due to the (high level) output signal of this AND i terminal 46,
The ItlIJwJ pressure regulating valve 15, which belongs to the partial braking circuit 1'' as an inlet valve and shuts off in its initial position O, is switched into the energized conducting position Ml.

As a result, above the speed limit value V3, the second partial braking circuit i'/ of the rear axle braking circuit I is connected to the continuously active partial braking circuit I', thus resulting in a braking force distribution increasing the proportion of the rear axle part. It is done. This change in the ratio of fJJ power distribution 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 axle load, which is stronger on the rear axle than on the front axle.

When the anti-lock device 10 acts to reduce the braking pressure on the rear axle, i.e. when the output signal of the first comparator 39 rises to a high signal level, the output signal of the AND element 46 disappears, thereby causing partial braking. Large mouth valve 1 belonging to circuit 1'/
5 to its initial position 0, the connectable partial braking circuit 1' causes the brake m which exits the main brake conduit 22 of the rear axle braking circuit I and supplies pressure to its second partial braking circuit 1// Blocked against ductal branches.

With the anti-locking device ffR+, 0 described so far, high driving speeds can be achieved in combination with a braking device that is fixedly matched to different values of the braking force distribution or that can be set continuously to different values of the braking force distribution. Considering the aerodynamic forces acting at
In order to be able to obtain as large a vehicle deceleration as possible, unlike conventional anti-lock devices, at high values of vehicle speed the pressure reduction operating limit value of the anti-lock adjustment only occurs at high values of wheel circumferential deceleration. The anti-locking device 10 is configured to obtain.

In the example shown, this is done by reducing the speed-related weighting factor xh according to equation (4) for the rear taxis 12 and 13, which weighting factor causes the wheel circumferential deceleration Zh to contribute to the comparison ff1xh. , this comparison quantity is compared with a base quantity, which in the example is normalized to the value of l.

The same is true for the front width brake, and the equation (1
) or 4) holds true.

Kv = Xv-Zv + Y-λv
(1')) [v = 1/ (Zmaxv +
ΔZo) (2')Y:
1/λmaxv
(3')Xv==Xov-b-v
(4') The parts of the electronic control unit 19 which are required in this connection in the calculator 38 and the comparator 39 for the front wheels of the vehicle are not shown for reasons of simplicity.

Penetration coefficients xb and Xv are determined by equations (4) and (4')
The constants Xoh and Xov and b, which are important for the formation of
For example, it can be determined by experiment using a roller test stand in a wind cylinder, or by taking into account aerodynamic forces, the following equations (5) and (5
') Maximum braking Zmaxh and Zmaxv obtained by
can be calculated by using in equations (3) and (3').

For the rear axle and for the front axle, in equation (5) Zblh indicates the locking limit of the rear wheel given by the following equation, and in equation (5') Zblv indicates the locking limit of the front wheel given by the following equation. There is.

The weights shown in equations (5) (5') (6) and (6') are determined 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 in N, φ is the rear axle load ratio with respect to the vehicle weight C, X is the height of the center of gravity with respect to mountain pressure, φ is the vehicle type LIG where hA is the front axle lift coefficient, KHA is the rear axle lift coefficient, Kw is the air resistance coefficient expressed in N5-2m-2, and V is the ms.
” is the speed expressed as “.

For a competition vehicle with the following data: φ = 0-4 KvA = 1 χ = 0.14 KHA = 2φ 0.6
Kv +0.6 G: 100OON Friction coefficient μV and μh at the front axle and rear axle are 1.
Equations (5) and (5) of the weighting coefficients xh and
5') gives the values summarized in Table I for a speed range of 0 to 70 as-'.

Table 1 0 10203040506070 Xv O,5440,5310,4960,4470,
3920, 3390, 2910 + 249 h O, 56
30,5460,5010,4400,3760,31
? 0.2660.223 As can be seen from the graph in this table shown in Fig. 2, both the xh curve R48 shown by the broken line and the XvaW& shown by the chain line, for a typical competition vehicle with the above data, the formula As shown in the general form by (4) and (4'), it is very well and therefore sufficiently approximated by a solid straight line 51 that satisfies the following equation.

X = 0.6-0.005・v (
7) The quadratic condition for this approximation, expressed by equation (7), is that X must always be greater than the larger of the values Xv or xh, i.e. X'2max (XV
+ xh ) holds, and the area between the curve given by the above equation and the straight line given by equation (7) or equation (4) or (4') must be minimum, that is, holds It is to be.

For the calculation of market coefficients Xv and xh the inertia of the wheels is also taken into account, in this case equations (4) and (4') Table 2 V O10203040506070Xy O,
5440, 5290, 4880, 4320, 3720,
3160,2670,225Xh O,5630,5
430,490 (L421 0.352 0.291
0.240 0+199 In order to make the diagram easier to read, the curves corresponding to the values in Table 2 are not shown in Figure 2.

[Brief explanation of the drawing]

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 action of the lock prevention device according to the first factor. 10...Lock prevention device, 12.13...Rear wheel brake, +9...Electronic wound device, 39.43...Comparator. The same thing can be said when xv=C−C(l−uv·χ−φ). From the calculation of these equations (8) and (8'), the values of Xv and xh, which are related to the speed and are kept in Table 2, are obtained,
There is only a slight difference from the values in Table 1. ~・2 Xvh 0 0 3θ 4θ 5θ 0 0 V/ms Zuno

Claims (1)

[Claims] 1. Due to the significant increase in front axle load and rear axle load that occurs at high speeds due to the aerodynamic configuration of road vehicles designed for high speeds, the circumferential wheel deceleration Zv or Zh of each wheel and the reference speed Comparison quantity Kv=Xv・Zv−Y・λv or Kh=Xh・Zh−V for the axle, formed as the sum of weighted values of the brake slip λv or λh for
If λh exceeds a limit value for the axle, which is compatible with stable dynamic behavior of the vehicle at high values of wheel deceleration,
At the wheel that requires adjustment, the anti-lock adjustment device starts operating so as to reduce the braking pressure of the wheel brake, and the weighting coefficients Xv, Xh and Y are standardized, and Xv
(Zmaxv+ΔZo)=1 or Xh(Zmaxh+ΔZo)
Zo)=1 and Y・λmaxv=1 or Y・λmaxh
= 1, Zmaxv or Zmaxh indicates the maximum value of the wheel circumferential deceleration with the maximum possible vehicle deceleration considering aerodynamic forces, and λmaxv or λmaxh indicates the maximum allowable value of the brake slip value. , and in the anti-lock adjustment method which shows a safety value with a value of about 0.3 in ΔZo, X≧max (Xv, Xh) and ∫^V^m^a^ )d
Decrease the weighting coefficient according to the following equation X=xo-b·v in relation to the vehicle speed v under the quadratic condition that v=min, so that Zmaxv and Zmaxh satisfy the following equation, Zmaxv=Zblv-[μv・K_v_A・v^2
]/[(1-μv・x-φ)・C]+Kv・v^2/G
Zmaxh=Zblh-[μh・K_H_A・v^2]
/(μh・x+φ)C+Kw・v^2/CZblv and Zblh using the following formula Zblv=[μv・(1−φ)]/[1−μv・x−φ
] and Zblh=μh・φ/μh・χ+φ where μv indicates the friction coefficient of the front axle, μh indicates the friction coefficient of the rear axle, φ indicates the load ratio of the rear axle, and χ indicates the distance between the axles. φ represents the rear axle braking force ratio with respect to vehicle weight, K_V
_A indicates the positive or negative lift coefficient of the front axle, K_H_A
An anti-lock adjustment method, characterized in that: indicates the positive or negative lift coefficient of the rear axle, K_w indicates the air resistance coefficient, and C indicates the vehicle weight. 2. If the brake system of a vehicle whose brake circuit is divided into a front axle brake circuit and a rear axle brake circuit is switchable between at least two brake force distribution values corresponding to different fixed alignments, the locking The electronic control unit (19) of the prevention device (10) includes a speed comparator (43) that generates an output signal for switching to a braking force distribution with a larger rear axle braking force proportion when the speed limit value is exceeded, and a comparison variable. a comparator (39) for comparing Kh with the operating limit value, which comparator (39) compares the small rear axle when the comparison quantity Kh reaches the reference quantity and the regulating device is operated to carry out a pressure reduction step. 2. 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 braking force proportion. 3 The rear wheel brakes (12, 13) are configured as 4-cylinder brakes, and the cylinder pair (
27, 28) are combined together with the cylinder pair (29, 31) of the other rear wheel brake machine (13) into partial braking circuits (II', II'') of the rear axle braking circuit (II), and these partial braking circuits One is cut off from the braking pressure generator (11) by the valve (17) below the speed limit value v_s;
) is controlled into the open position by the output signal of the speed comparator (43). 4. In order to switch the braking force distribution, a parent cylinder that can switch the braking pressure distribution is provided,
4. The device according to claim 3.