JPS6313092Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a skid brake system that controls the brakes by an integral comparison circuit that compares a current representing wheel deceleration with a reference current that changes to form an assumed wheel speed shape. Regarding a control device. In particular, the reference current initially has a value representative of the wheel deceleration occurring during the initial skid condition. The integral comparison circuit receives a reference current and a current representative of wheel deceleration and provides an output signal when the current representative of wheel deceleration exceeds the reference current by a predetermined amount of wheel speed. The reference current generation circuit increases the reference current to a significantly higher level in response to the output signal of the comparator circuit. If the current representing wheel deceleration exceeds the above-mentioned significantly high level within a predetermined period of time, the output signal from the comparator circuit will be maintained and the brakes will be released. If the current representing wheel deceleration does not exceed the above-mentioned significantly high level within a predetermined period of time, the output signal of the integral comparison circuit will terminate and the brake will not be released. Assuming the brake is released, the reference current generating circuit reduces the reference current to a very low level after a predetermined period of time. The output signal of the integral comparator circuit stops and the brake re-applying starts after a predetermined time when the current representing the wheel deceleration no longer exceeds the reference current set by the integral comparator circuit. There is. This period is set to allow the wheels to spin up and approximate the assumed wheel speed profile. At high mu surfaces, the current representing wheel deceleration typically quickly becomes much smaller than the reference current, causing the output of the integral comparator circuit to stop and reapplying the brakes while the high level reference current is occurring. For low-view surfaces,
The current representing wheel deceleration typically becomes much less than the reference current after a period of time, causing the output of the integral and comparison circuit to stop and reapplying the brakes during the low level reference current.

The skid controller of the present invention utilizes a simple circuit with fewer components to provide skid control performance that meets or exceeds the performance of the more complex conventional skid controllers. The device can be easily constructed using conventional operational amplifiers. Since these operational amplifiers are produced in large quantities for various applications and are therefore inexpensive, the skid control system of the present invention can be produced very inexpensively.

As described above, the skid control system of the present invention has the ability to detect conditions representing an emergency or possible emergency skid condition and pre-treat the skid condition. Furthermore, it is an inexpensive and highly reliable skid control device with a configuration that is less susceptible to the effects of noise within the circuit.

FIG. 1 shows a skid control system 10 according to the present invention. The skid controller 10 receives a signal having a frequency representing the speed of the left wheel (front or rear) of the car in line 12 and a signal having a frequency representing the speed of the right wheel (front or rear) of the car in line 14. and received. The signals on lines 12 and 14 are
The frequency of the analog converters 16 and 18 converts the signal into a DC signal with a magnitude representing the wheel speed, respectively. Signals from analog converters 16 and 18 are sent to low wheel/high wheel selection circuit 20 on line 2.
A signal representing the low wheel speed of line 2 and the high wheel speed of line 24 is generated. The signal on line 22, representing low wheel speed, is sent to a wheel speed differential/integral comparison circuit 26, which is shown in detail in FIG. The wheel speed differential/integral comparison circuit 26 is the reference current generation circuit 3
0 to accept the reference current on line 28.

The reference current generation circuit 30 has a first current source 32, which has a current rate of, for example, 30.5 to 182.9 cm/sec ² (1
~6ft/sec ² ), preferably 152.4cm/sec ² (5ft/
It generates a current representing a very low wheel deceleration of sec ² ). The reference current generation circuit 30 also includes a second
a current source 34, which together with a first current source;
Generate ^a current representative of ^{the wheel} deceleration occurring during or just before the initial skid condition ^, e.g. . Reference current generation circuit 3
0 further includes a third current source 36, which is ^e.g.
sec ² ), preferably 3657.6cm/sec ² (120ft/sec ² )
produces a current representing a very high wheel deceleration, which is significantly greater than the maximum non-skidded wheel deceleration. An inverter 38 is connected to receive the output signal on line 40 of the wheel speed differential/integral comparison circuit, and the signal from this inverter 38 causes the second
A current source 34 is output. A one shot multivibrator 42 is also connected to receive the output signal of the line 40 of the wheel speed differential/integral comparison circuit, and the signal from this multivibrator causes the third current source 36 to output and then output controlled to stop. The period of the output pulse of this single-shot multivibrator 42 is 60 to 90 milliseconds, preferably 60 milliseconds. For the reasons described below, between the single-shot multivibrator 42 and the third current source 36,
An OR gate 44 is interposed.

The solenoid drive device 46 is an output OR gate 48
receives the output signal from the wheel speed differential/integral comparison circuit in line 40 via the circuit. A solenoid drive 46 is connected to the modulating valve to control the pressure to the vehicle's brakes. Preferred modulating valves have a "knee" of the brake pressure rise curve. For example, one example of such a modulating valve is U.S. Pat. No. 3,560,056 owned by Stelza, issued February 2, 1971.
Disclosed in the issue. Instead of a modulating valve having an "elbow" in the brake pressure rise curve, a wheel acceleration detector is used in conjunction with an acceleration control pulse modulator to detect the wheel spin-up rate and pulse the modulating valve during wheel spin-up; Braking may then be applied earlier for higher wheel spin-up speeds.

The skid control device 10 incorporates a wheel speed differential overdrive circuit 50, which outputs
In cooperation with the OR gate 48, the speed difference between the fastest rotating wheel and the slowest rotating wheel is reduced per second.
Release the brake when exceeding 457.2 cm (15 feet). This wheel speed difference overdrive circuit 5
0 receives a current source 52 representing a reference wheel speed signal of 15 feet per second and a reference wheel speed signal and a high wheel speed signal to determine a speed 15 feet per second less than the high wheel speed. and a differential operational amplifier 54 that generates an output signal representing the output signal. Comparator circuit 56 receives the output signal of differential operational amplifier 54 and the low wheel speed signal from line 22 and determines that the low wheel speed is greater than the high wheel speed per second.
Whenever it falls below 15 feet, it sends an output signal to output OR gate 48 which in turn sends a signal to solenoid drive 46 to release the brake.

Reset timing circuit 58 accepts the output of solenoid drive 46 and sends a signal to OR gate 44 whenever the duration of the output signal from solenoid drive 46 exceeds 1.5 seconds. As a result, the output signal to the modulating valve is
Whenever 1.5 seconds are exceeded, the third current source generates a current representing high wheel deceleration.

FIG. 2 shows a typical circuit diagram of a wheel speed differential/integral comparison circuit 26 used in the apparatus of the present invention. This wheel speed differential/integral comparison circuit 26
has a differential capacitor 60 which receives a current in line 22 representing the speed of the wheel and sends to node 62 a current representing the deceleration of the wheel.
Since the reference current in line 28 is also routed to node 62, this node 62 serves as a current summing node. A resistor 64 connects the net current at node 62 to the base of transistor 66. The collector of transistor 66 is connected to output line 40 and to power supply B+ via resistor 68, while the emitter of transistor 66 is grounded. As a result, transistor 66 is normally held conductive by the reference current in line 28, so that line 40
The output signal of is usually low.

Since transistor 66 is normally held conductive by a reference current flowing through resistor 64 to the base of transistor 66, a voltage drop appears across resistor 64 to maintain node 62 above ground potential. Before transistor 66 is opened to produce an output signal on output line 40, the potential at node 62 must be reduced to substantially ground potential.
Transistor 66 is therefore opened and line 40
The wheel speed signal then decreases at a sufficient speed and to a sufficient extent before an output signal is produced at connection point 62, and the current representing the wheel deceleration received at connection point 62 flows through line 28.
It is necessary not only to balance the reference current of , but also to overcome the voltage drop across resistor 64 . This operation was started in 1973.
It is further described in detail and graphically illustrated in U.S. Pat. No. 3,966,266 to Rah Atkins, filed September 2007 and assigned to the same assignee as the present application, the disclosure of which is incorporated herein by reference.

From an operational standpoint, the voltage drop across resistor 64 requires that the wheel speed signal drop by a predetermined amount after the wheel deceleration reaches a level that is commensurate with the wheel deceleration represented by the reference current. . This requirement is met by a predetermined amount of wheel speed reduction as opposed to an increase in deceleration, so this requirement can be met by a large excess of wheel deceleration for a short period of time, or by a slight excess of wheel deceleration over a long period of time. Satisfied by excess deceleration. In other words, the integral of deceleration over time must reach a value representing a constant wheel speed reduction to overcome the voltage drop across resistor 64. This requirement is referred to herein as a "relationship predetermined by the comparison circuit configuration." For this reason, circuit 26 is referred to herein as an integral comparator circuit.

In FIG. 3, possible wheel speed operating conditions are illustrated by wheel speed diagrams. Also the third
The diagram shows an integral diagram of the reference current and the output signal of the differential-integral comparison circuit 26 appearing on line 40. Although reference current integration does not actually exist in the circuit, it is shown in FIG. 3 to illustrate the principles of the invention. In this regard, the integral of the reference current represents a hypothetical velocity shape that corresponds to the magnitude of the reference current and the sequence in which it changes. This hypothetical speed profile is indirectly compared to the wheel speed by means of a device that compares a reference current with a current representative of wheel deceleration.

In FIG. 3, when the wheel starts to decelerate, at time t1, the wheel is moving at (sum of current from the first current source 32 and second current source 34) 670.6 cm/sec ² (22 ft/
sec ² ), the voltage drop across resistor 64 causes the speed to decrease by a predetermined amount, producing an output signal on line 40 from wheel speed differential/integral comparison circuit 26. The signal on line 40 is sent to a single-shot multivibrator 42 and an inverter 38, and a second current source 3
4 is opened and the third current source 36 is closed (sum of currents from the first current source 32 and third current source 36) 3810
Create a new reference current representing a wheel deceleration of cm/sec ² (125 ft/sec ² ). In the example shown in Figure 3, the wheels have a deceleration of 3810 cm/sec ² set by the reference current.
(125ft/ ^sec2 ) or more, the output signal on line 40 from the wheel speed differential/integral comparison circuit terminates at time t2. Within the very short time that the output signal on line 40 was sent, the modulating valve was not activated and the brake was not released due to its inherent inertia. The wheel speed is 670.6 cm/sec ² during the operating period of the single multivibrator 42, that is, between times t1 and t3.
The wheel speed differential/integral comparator circuit 26 does not close ^again because the third current source 36 continues to send its high level current.
From the above, it can be seen that although there are conditions that represent possible emergency skid conditions, skid conditions do not actually occur. Nevertheless, the skid controller 10 is responsive to possible emergency skid conditions so that
The reaction time will be shorter in the case of actual squid conditions.

In FIG. 4, a possible wheel action pattern in the low-view plane is shown. At time t4, the wheel decelerates 670.6 cm/sec ² (22 ft/
sec ² ) and the wheel speed is then reduced as necessary to provide an output signal on line 40. Since the wheels are in the low-view plane, wheel deceleration continues at a high rate, thereby increasing the wheel speed difference in vehicle speed as shown. Third current source 3
6 is output for the operating period of the single-shot multivibrator 42, for example 60 milliseconds, while the second current source 34
is opened as described above. After a period of activation of the single-shot multivibrator 42, at time t5, the third current source 36 is turned off, resulting in a low level reference current available only from the first current source 32 at time t5. Because of the large deviation of the wheel speed from the vehicle speed, the potential at node 62 has been dropped far below ground potential. As a result, the transistor 66 is not closed until the wheel has been accelerated for a considerable time, and the potential at the connection point 62 is raised to a level exceeding ground potential, and at time t6, the transistor 66 is closed.
6 is closed. Accordingly, the condition shown in FIG. 4 is approached which causes the wheel speed to return to the hypothetical ramp represented by each current source. As a result, the wheels are allowed to recover from the skid condition before the output signal on line 40 goes low again and the brakes are not reapplied.

In FIG. 5, a possible wheel speed effect diagram for a high-view surface is shown. At time t7, the wheel decelerates at a rate exceeding 670.6 cm/sec ² (22 ft/sec ² ) set by the first and second current sources 32, 34, and the speed decreases by a predetermined amount over time. An output signal appeared on line 40 at t7. As a result, at time t7, single-shot multivibrator 4
2 activates the third current source 36 and the output signal on line 40 opens the second current source 34 to generate a reference current representing a hypothetical fast ramp as shown. Since the wheels are in the high-view plane, the wheel speed recovers quickly so that at time t8 the hypothetical ramp is reached and there is no output signal from the wheel speed differential/integral comparison circuit 26 on line 40. in fact,
The deceleration of the wheels caused the potential at connection point 62 to fall below ground potential. After the wheel begins to accelerate, the potential at node 62 is increased sufficiently by increasing the wheel speed to raise the potential at node 62 above ground potential again to close transistor 66 at time t8. It can be seen in the wheel speed diagram of FIG. 5 that the above process repeats between times t9 and t10 and between times t11 and t12.

In FIG. 6, a possible wheel speed profile is shown in a high vehicle plane with very little normal force on the wheels during braking conditions. In this regard, under certain high torque braking conditions, a very small load or vertical force is applied to both rear wheels of a short wheel-based truck with an empty cargo hold, so that the rear wheels are The time starts to slow down at
At t14, a sudden lock-up state occurs. It can be seen that the wheel speed begins at time t15 and slowly recovers to the vehicle speed. Since the vehicle is on a high-level plane, the vehicle slows down enough that the vehicle speed actually drops below the assumed ramp so that the wheels that are slowly spinning up never reach the assumed ramp. Therefore, the brake remains released. To avoid such continuous brake release conditions occurring even after the wheels have reached actual vehicle speed, a reset timer 58 is provided to measure the duration of the output signal from the solenoid drive 46. When the duration of the solenoid drive output signal reaches 1.5 seconds at time t16, the reset timer pulses OR gate 44 which issues an output signal causing third current source 36 to output. The third current source 36 sends a relatively high level current to the wheel speed differential/integral comparison circuit 26, thereby raising the potential at the connection point 62 and closing the transistor 66 at time t17, thereby transmitting an output signal to the modulation valve and braking. React. In reality, the output of this third current source 36 causes the hypothetical ramp to move rapidly downward to reach vehicle speed at time t17 and reapply the brakes. After reapplying the brakes, the brakes repeat the process in accordance with the wheel speed effects of the high-view surface, as illustrated in FIG. 5 and also shown in the right-hand portion of the wheel speed diagram in FIG.

In the embodiment disclosed herein, the wheel speed differential
Although the integral comparison circuit 26 is illustrated as accepting the lowest wheel speed of a pair of wheels, the device may also be used with the average wheel speed of a pair of wheels or the maximum wheel speed of a pair of wheels. You can also do that.
When using average wheel speed, the brakes are released when the "averaged" wheels skid.
This means that both wheels become skidded or
This means that one of the wheels will enter a severe skid state and the other will not start to skid. If high wheel speeds are utilized, the brakes will not be released until both wheels are skidded.

In explaining the operation of the skid controller 10, an important feature of the skid controller is the ability to detect conditions indicative of an emergency or possible emergency skid condition and to pre-handle a skid condition. To achieve this capability, the brake signal must be activated in response to relatively small wheel decelerations that indicate that the wheels are skidded, but only as the wheels approach the skidded condition and indicate the occurrence of a brake release condition. Just send it to the modulating valve. In the device of the present invention, an inhibiting device is provided to eliminate the signal before the brake modulation valve actually issues a brake release command, and this device allows the signal sent to the brake modulation valve to actually act effectively to release the brake. It is set not to be released. Therefore, the response time of the system to actual skid conditions is reduced.

From the above description of the skid controller 10 of the present invention, it can be seen that it utilizes a very simple control logic, especially in light of the complexity of skid controllers currently in use.

As described above, the skid control system of the present invention has the ability to detect conditions representing an emergency or possible emergency skid condition and pre-treat the skid condition. Furthermore, it is an inexpensive and highly reliable skid control device with a configuration that is less susceptible to the effects of noise within the circuit. The skid control device of the present invention has been described as a typical example. A notable feature of the skid control system is that it can be constructed using conventional operational amplifiers that are produced in large quantities for a variety of applications and are therefore inexpensive. Therefore, the skid control device of the present invention can be produced at a very low cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the skid control device according to the present invention, FIG. 2 is a block diagram showing a typical example of an integral comparison circuit used in the skid control device of the present invention, and FIG. 3 is a block diagram of the skid control device shown in FIG. 1. A first example showing the operation of the control device, FIG. 4 a second example showing the operation of the skid control device shown in FIG. 1, and FIG. 5 a third example showing the operation of the skid control device shown in FIG.
EXAMPLE FIG. 6 is a fourth example illustrating the operation of the skid control device shown in FIG. 10 is a skid control device, 16 and 18 are analog converters, 20 is a low wheel/high wheel selection circuit, 26
30 is a reference current generation circuit; 32 is a first current source; 34 is a second current source; 36 is a third current source; 38 is an inverter;
46 is a single-shot multi-vibrator, 46 is a solenoid drive device, 54 is a differential operational amplifier, 58 is a reset timing circuit, and 66 is a transistor.

Claims (1)

[Claim for Utility Model Registration] A skid control device for a vehicle having multiple wheels and brakes for the wheels, comprising a wheel speed detection device, a high wheel/low wheel selection circuit 20 for the output of the device, and a brake for the low wheel. a wheel speed difference overdrive circuit 50 that detects a speed difference of more than a predetermined value between the high wheel and the high wheel; a reference current generation circuit 30 that generates a reference current; and a low wheel speed signal from the low wheel/high wheel selection circuit 20. a wheel speed differential/integral comparison circuit 26 which receives and compares the reference current from the reference current generation circuit 30 and generates a signal when the deceleration of the low wheel speed falls below a reference value based on the reference current; , a brake modulator that modulates the brake based on the signal, and a duration of the output signal from the solenoid drive device 46 of the brake modulator.
If it exceeds 1.5 seconds, the reference current generating circuit 30's OR
a reset timing circuit 58 that sends a signal to the gate 44;
2, and a second current source 34 for generating a current representative of the wheel deceleration during or just before the initial skid condition.
and a third current source 36 that generates a current representing a significantly higher wheel deceleration than in the non-squeezed condition.
a single-shot multivibrator 42 that receives the output signal of the wheel speed differential/integral comparison circuit 26 and outputs a third current source 36; and a second current source that receives the output signal of the wheel speed differential/integral comparison circuit 26. 3
In response to the initial output signal of the wheel speed differential/integral comparison circuit 26, the reference current generation circuit 30 generates a current from the sum of the first current source 32 and the second current source 34. First current source 3
2 and the third current source 36, and decrease the reference current to only the current of the first current source 32 with a time delay determined by the single-shot multivibrator 42, and the reset timing circuit 58 A skid control device characterized in that the third current source 36 is output by a signal from the skid control device.