US3820857A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automotive wheel brake anti lock system
Assignee: Robert Bosch GmbH
•
Filing: 1973-01-22
•
Granted: 1974-06-28
•
Expires: 1993-01-22
Abstract
Abstract To prevent skidding, particularly of the driven wheels, an acceleration signal of the driven wheels is provided which is applied to at least two, preferably three or four threshold switches which have different responses to levels of wheel acceleration or deceleration; a first threshold switch, when responding to wheel deceleration, controls interruption of supply of pressurized brake fluid to the wheel brakes and bleeding of pressurized brake fluid to lower braking effort; a second threshold switch responds to wheel acceleration to prevent unduly long draining of pressurized brake fluid and thus loss of braking effort; preferably a third threshold switch is provided responsive to only a low level of wheel deceleration to prevent draining of pressurized brake fluid and hold braking effort at a level below skidding. Preferably, a pulse source is provided to permit pulsed application of pressurized brake fluid to the wheel brakes and thus gradually increase wheel braking pressure to further increase braking effort until the first deceleration switch again responds.
Inventors
- 👤 E Schnaibel
- 👤 W Gotz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:40
CPC Classifications
B; B60; B60T; B60T8/00; B60T8/17; B60T8/173; B60T8/176; B60T8/1761; B60T8/17613
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
368 words
Wheel anti-lock system for fluid operated brakes (14, 15) having rate-of-change wheel speed sensing means (31; 27, 28, 30, 130); a source of brake fluid under pressure (10, 18) and a pressure fluid sump (17); controllable pressure valve means (13, 20) selectively connecting the source of pressurized brake fluid to the wheel brakes (14, 15); controllable drain valve means (16, 21) selectively connecting the wheel brakes (14, 15) to the sump (17); and a control system to selectively control said pressure valve means and said drain valve means comprising at least two threshold switches (41, 42) a first switch (41) being responsive to a deceleration signal and a second switch (43) responding to an acceleration signal, said switches being connected to and controlled by the sensing means; the first tHreshold switch (41) including a threshold control input (V'') connected to change the threshold level setting of said first threshold switch to a value of deceleration much lower than the deceleration value when the control input (V'') is energized; timing means (36) connected to and controlled by the output of said second threshold switch (42), and having its output connected to the threshold control input (V'') of the first threshold switch (41) to change the threshold response level of the first threshold switch (41) after response of the second threshold switch for a limited time period, to prevent spurious response of the first threshold switch due to disturbing pulse peaks arising in the system, independently of braking action of the wheel with respect to the road surface; a first signal storage means (45) having set (S) and reset (R) inputs, the set and reset inputs being connected to and controlled by the first (41) and second (42) threshold switches, respectively; the drain valve means (16, 21) being controlled by the output from the first storage means (45) upon sensing of deceleration exceeding the threshold level (b1) of the first threshold switch; means (49) disjunctively controlling the pressure valve means to close and interrupt application of further pressurized fluid to the wheel brakes upon application to said disjunctive means of an output signal of a. the first storage means (45) or b. the output of the second threshold switch (42).
Claim 2
Dependent Claim
368 words
Wheel anti-lock system for fluid operated brakes (14, 15) having rate-of-change wheel speed sensing means (31; 27, 28, 30, 130); a source of brake fluid under pressure (10, 18) and a pressure fluid sump (17); controllable pressure valve means (13, 20) selectively connecting the source of pressurized brake fluid to the wheel brakes (14, 15); controllable drain valve means (16, 21) selectively connecting the wheel brakes (14, 15) to the sump (17); and a control system to selectively control said pressure valve means and said drain valve means comprising at least two threshold switches (41, 42) a first switch (41) being responsive to a deceleration signal and a second switch (43) responding to an acceleration signal, said switches being connected to and controlled by the sensing means; the first tHreshold switch (41) including a threshold control input (V'') connected to change the threshold level setting of said first threshold switch to a value of deceleration much lower than the deceleration value when the control input (V'') is energized; timing means (36) connected to and controlled by the output of said second threshold switch (42), and having its output connected to the threshold control input (V'') of the first threshold switch (41) to change the threshold response level of the first threshold switch (41) after response of the second threshold switch for a limited time period, to prevent spurious response of the first threshold switch due to disturbing pulse peaks arising in the system, independently of braking action of the wheel with respect to the road surface; a first signal storage means (45) having set (S) and reset (R) inputs, the set and reset inputs being connected to and controlled by the first (41) and second (42) threshold switches, respectively; the drain valve means (16, 21) being controlled by the output from the first storage means (45) upon sensing of deceleration exceeding the threshold level (b1) of the first threshold switch; means (49) disjunctively controlling the pressure valve means to close and interrupt application of further pressurized fluid to the wheel brakes upon application to said disjunctive means of an output signal of a. the first storage means (45) or b. the output of the second threshold switch (42).
Claim 3
Dependent Claim
122 words
System according to claim 1, further comprising a third threshold switch (43) connected to and controlled by the sensing means (31), said third threshold switch having an inverted output and responding to a deceleration signal less than that of the first threshold switch; an AND-gate (46); the input to the AND-gate (46) being connected to and controlled by the output of the first storage means (45) and the negative of the output of the third threshold switch (43), the output of said AND-gate (46) being connected to and controlling said drain valve means (16) to provide for control of the drain valve by the conjunction of signals from the first threshold switch (41) and the inverse of the third threshold switch (43).
Claim 4
Dependent Claim
120 words
System according to claim 2, wherein the third threshold switch (43) includes a threshold control input (V) connected to change the threshold setting of said third threshold switch from a low value of deceleration to a small value of acceleration, and timed delay means (35) are provided, connecting the output of the first threshold switch (41) to the threshold control (V) of the third threshold switch (43) to change the threshold response level of the third threshold switch after response of the first threshold switch (41) and permit prolonged opening of the drain valve (16, 21) unless the wheel is accelerating rapidly, rapid acceleration being indicative of low frictional contact between wheel and road surface, and hence slippery road conditions.
Claim 5
Dependent Claim
115 words
System according to claim 2, wherein at least one of the threshold switches (41, 42, 43) includes a threshold control input connected to change the threshold setting of the respective threshold switch; the threshold switch including an operational amplifier (410), a voltage divider (415, 416, 417) connected to the input of the operational amplifier to determine the threshold level setting of the respective operational amplifier; a transistor (419) having its emitter-collector path in parallel to a portion of the voltage divider; the base connection to the transistor forming the threshold control input, conduction or non-conduction of the transistor changing the voltage divider ratio, and hence the voltage applied to the input of the operational amplifier.
Claim 6
Dependent Claim
54 words
System according to claim 2, comprising a low pass filter (34) having the rate of velocity change signal applied to its input, the output of the low pass filter being connected to the first (41) and second (42) thresHold switches; the third threshold switch being connected directly to the output of the sensing means.
Claim 7
Dependent Claim
40 words
System according to claim 1, comprising a low pass filter (34) having the rate of velocity change signal applied to its input, the output of the low pass filter being connected to the first (41) and second (42) threshold switches.
Claim 8
Dependent Claim
20 words
System according to claim 6, wherein the frequency cut off of the low pass filter (34) is approximately 18 Hz.
Claim 9
Dependent Claim
40 words
System according to claim 7, comprising a low pass filter (34) having the rate of velocity change signal applied to its input, the output of the low pass filter being connected to the first (41) and second (42) threshold switches.
Claim 10
Dependent Claim
20 words
System according to claim 8, wherein the frequency cut off of the low pass filter (34) is approximately 18 Hz.
Claim 11
Dependent Claim
112 words
System according to claim 1, further comprising a fourth threshold switch (144) connected to and controlled by said sensing means (31); a timing circuit (151) connected to the output of the fourth threshold switch (144) and delaying the output signals from said fourth threshold switch for a predetermined interval, after response of said fourth threshold switch, said fourth threshold switch being connected to control said first signal storage means said fourth threshold switch responding to a deceleration signal at a level less than said first threshold switch, to set said storage means upon sensing of a low deceleration level for a period of time exceeding the timing period of said timing circuit.
Claim 12
Dependent Claim
61 words
System according to claim 10, wherein said timing circuit comprises a monostable multivibrator (151) and a NAND-gate (152), having its other input connected to the output of said fourth threshold switch (144) to provide an output if and only if: a. said fourth threshold switch (144) has responded and b. the unstable time period of said monostable circuit (151) has elapsed.
Claim 13
Dependent Claim
39 words
System according to claim 10, further comprising an OR-gate (153) connecting, disjunctively, the output of said first threshold circuit (141), or said fourth threshold circuit (144), over said timing means (151) to said first signal storage means (45, 145).
Claim 14
Dependent Claim
72 words
System according to claim 1, wherein the change of wheel speed sensing means comprises means (128, 129) to provide separate output signals representative of speeds of individual wheels; an averaging circuit (154) connected to have the separate output signals of said output signal generating means applied thereto; and a differentiator (130) having the output from said averaging circuit connected thereto to provide an averaged differentiated rate of change of wheel speed signal.
Claim 15
Dependent Claim
70 words
System according to claim 13, further comprising an extreme value circuit (155) connected to have the separate output signals of said output signal generating means applied thereto; a comparator circuit (156), the comparator circuit being connected to said extreme value circuit (155) and to said averaging circuit (154) and providing an output when the difference between the average wheel speed signal, and an extreme wheel speed exceeds a predetermined limit.
Claim 16
Dependent Claim
86 words
System according to claim 14, further comprising disjunctive coupling means (153) connected to the output of said comparator circuit and to the output of said first threshold circuit, and being connected to and controlling said first signal storage means, so that said first signal storage means will be set upon either a. the deceleration threshold level of said first threshold switch (41) being passed, or b. the difference between average wheel speed and the extreme speed of any one of the wheels exceeding a predetermined value.
Claim 17
Dependent Claim
63 words
System according to claim 14, wherein the extreme value circuit (155) comprises a diode (551, 552), each, connected to the output of a respective output signal generating means (128, 129), and a common output resistor (553) connected to the other terminals of all the diodes, together, to provide an output signal representative of the maximum signal supplied to any one of the diodes.
Claim 18
Dependent Claim
39 words
System according to claim 14, wherein the comparator comprises an operational amplifier (560) having one input connected to the output of the extreme value circuit (155) and the other input connected to the output of the averaging circuit (154).
Claim 19
Dependent Claim
61 words
System according to claim 17, further comprising a transistor (563) connected to the output of the operational amplifier (560) of the comparator (156), the output of the comparator (156) being taken from the emitter-collector circuit of the transistor; and a feedback resistor (565) connected to the output of the transistor (563) and one of the inputs of the operational amplifier (560).
Claim 20
Dependent Claim
36 words
System according to claim 13, wherein the averaging circuit (154) comprises an operational amplifier (540) and adder resistors (541, 542) coupling the output from said output signal generating means to the input of the operational amplifier.
Claim 21
Dependent Claim
20 words
System according to claim 19, further comprising an inverter amplifier (547) connected to the output of the operational amplifier (540).
Claim 22
Dependent Claim
100 words
System according to claim 1, further comprising an additional threshold circuit (144) including a fourth threshold switch (144, 151) responding to a level of acceleration less than first threshold switch and timed delay means inhibiting delivery of an output signal from said additional threshold circuit for a predetermined time interval; and means (153) connecting the output from said additional threshold circuit to said controlled drain valve switching means (45, 145) to enable said drain valve a. after said predetermined time delay and b. upon response of said fourth threshold switch or c. upon response of said first threshold switch (41).
Claim 23
Dependent Claim
24 words
System according to claim 1, including timing means (35, 36) controlling change of threshold response levels, and connected to respective threshold switches (41, 43).
Claim 24
Dependent Claim
19 words
System according to claim 22, wherein the timing period of the timing means (35, 36) is about 50 milliseconds.
Claim 25
Dependent Claim
311 words
In an automotive brake anti-lock and skid system, to prevent skidding of wheels on road surfaces upon operation of a brake controller (23a), particularly for the rear wheels, in which the wheels have brake fluid cylinders (14, 15), means (31) determining acceleration or deceleration of at least one of the wheels; means (18, 19) providing a source of brake fluid under pressure and means (17) providing a drain for unpressurized brake fluid; pressure valve means (13, 20) and drain valve means (16, 21) connecting the respective wheel brake cylinders to, respectively, the pressure source or the drain; means (23a) disabling the system unless the brake controller is operated; a first threshold switch (41) having a controllable threshold level and normally responding to a level of wheel deceleration resulting in wheel skidding; a controlled drain valve switching means (45) enabled by said first threshold switch and connected to effect draining of pressurized brake fluid from the respective wheel brake cylinder; second controlled switching means (50) connected to inhibit supply of pressurized brake fluid to the wheel cylinder when the drain valve is controlled to be open; a second threshold switch (42) responding to a level of wheel acceleration without skidding connected to control the threshold level of said first threshold swtich (41) to lower the response of the threshold level, for a predetermined time period after response of said second threshold switch (42) to prevent spurious response of the system, said second threshold switch further being connected to control the drain valve switching means (45) to interrupt draining of pressurized brake fluid from the wheel cylinder upon sensing of wheel acceleration to hold the wheel brake fluid pressure at a constant level upon interruption of supply of pressurized brake fluid to the respective wheel Brake cylinder by the second switching means (50) and interruption of draining of fluid from the wheel cylinder.
Claim 26
Dependent Claim
311 words
In an automotive brake anti-lock and skid system, to prevent skidding of wheels on road surfaces upon operation of a brake controller (23a), particularly for the rear wheels, in which the wheels have brake fluid cylinders (14, 15), means (31) determining acceleration or deceleration of at least one of the wheels; means (18, 19) providing a source of brake fluid under pressure and means (17) providing a drain for unpressurized brake fluid; pressure valve means (13, 20) and drain valve means (16, 21) connecting the respective wheel brake cylinders to, respectively, the pressure source or the drain; means (23a) disabling the system unless the brake controller is operated; a first threshold switch (41) having a controllable threshold level and normally responding to a level of wheel deceleration resulting in wheel skidding; a controlled drain valve switching means (45) enabled by said first threshold switch and connected to effect draining of pressurized brake fluid from the respective wheel brake cylinder; second controlled switching means (50) connected to inhibit supply of pressurized brake fluid to the wheel cylinder when the drain valve is controlled to be open; a second threshold switch (42) responding to a level of wheel acceleration without skidding connected to control the threshold level of said first threshold swtich (41) to lower the response of the threshold level, for a predetermined time period after response of said second threshold switch (42) to prevent spurious response of the system, said second threshold switch further being connected to control the drain valve switching means (45) to interrupt draining of pressurized brake fluid from the wheel cylinder upon sensing of wheel acceleration to hold the wheel brake fluid pressure at a constant level upon interruption of supply of pressurized brake fluid to the respective wheel Brake cylinder by the second switching means (50) and interruption of draining of fluid from the wheel cylinder.
Claim 27
Dependent Claim
70 words
System according to claim 24, further comprising a third threshold switch (43) responding to a level of wheel deceleration of a lesser level than the first threshold switch and providing an enabling signal (46) for the drain valve means (16) conjointly with output from the first threshold switch (41) to permit extended draining by said drain valve means if the threshold level of said first threshold switch is not passed.
Claim 28
Dependent Claim
82 words
System according to claim 25, wherein the third threshold switch (43) has a controllable threshold level, said first threshold switch (41) being connected to control the threshold level of said third threshold switch (43) to increase the response level from negative acceleration to positive acceleration, for a predetermined time period (35) after response of the first threshold switch (41) and enable operation of the drain control valve upon subsequent or further response of the first threshold switch after it has first responded.
Claim 29
Dependent Claim
80 words
System according to claim 25, wherein said first threshold switch (41) has a threshold level of about -3g; said second threshold switch (42) has a threshold response level of about +1g, with hysteresis to reset at about 0g; and the third threshold switch (43) has a threshold level of about 1g; and the change in the threshold response levels of the first and third threshold switches is in a direction to greater deceleration, before response of the respective threshold switch.
Claim 30
Dependent Claim
55 words
System according to claim 25, comprising a low pass filter (34) having the rate of velocity change signal applied to its input, the output of the low pass filter being connected to the first (41) and second (42) threshold switches; the third threshold switch (43) being connected directly to the output of the sensing means.
Claim 31
Dependent Claim
72 words
System according to claim 24, wherein the controlled drain valve switching means (45) includes a reset timing feature to change state automatically after a predetermined interval to inhibit operation of the drain valve a. after said predetermined interval has been exceeded and b. in the absence of a signal from the second threshold switch (42) to prevent excessive drainage of brake fluid from the brake cylinder in case of any equipment malfunction.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |