Abstract: A method for controlling an automated clutch, which comprises a hydraulic clutch actuating system having a hydrostatic actuator, the pressure of which is detected. The method includes using the pressure of the hydrostatic actuator to adapt the characteristic curve of the clutch.

Abstract: A check valve having a spherical valve body received in a valve chamber, a valve seat for blocking the flow of fluid from the valve chamber toward an inflow port when having the spherical valve body seated thereon, and a plate-like resilient member arranged across the valve chamber. The resilient member has an annular fixed portion fixed on a circumferential wall of the valve chamber and a tongue piece portion radially extending from a radial one side of the annular fixed portion to extend an end thereof beyond an inner edge on a radial other side of the annular fixed portion. The tongue piece portion is formed to be deflected toward the valve seat side from the fixed portion and is resiliently contacted with the spherical valve body at a center part thereof for disengageably pressing the spherical valve body against the valve seat.

Abstract: A pressure balanced supply valve for use in a vehicular braking system. A housing defines a first chamber, a second chamber, a first fluid conduit for connection to a master cylinder, a second fluid conduit for connection to a hydraulic pump, and a third fluid conduit connected between the first and second fluid conduits. The second fluid conduit communicates with both the first chamber and the second chamber. A valve seat is defined in the third fluid conduit. A movable valve element is movable to a first position sealing against the valve seat to prevent fluid flow between the first and second conduits through the third conduit, and to a second position permitting fluid flow between the first and second conduit through the third conduit. The movable valve element is exposed to pressures in both the first and second chambers so as to be pressure balanced in operation.

Abstract: A brake system and a brake device for use with automobiles is provided in which braking energy stored in an auxiliary pressure source can be effectively used for braking, even if an electrical system fails. The vehicle brake system includes a proportional pressure control valve for generating braking liquid pressure by adjusting the braking energy stored in the auxiliary pressure source. A passage transmits the liquid pressure generated by a brake pedal stroke, a switching valve opens the passage in the powered condition and closes the passage in the off-powered condition, and an auxiliary control portion activates the proportional pressure control valve. Even in the off-powered condition, the high pressure accumulated in the auxiliary pressure source can be used to adjust the required braking liquid pressure at the proportional pressure control valve.

Abstract: A transmission member that transmits urging force of a helical spring to a valve body is disposed between the valve body and the helical spring. The transmission member changes a direction of an urging force transmitted to the valve body such that the urging force is oblique to a pressure action direction X. Accordingly, when a check valve is in an open state, the valve body is pressed against a side wall and thus vibration of the valve body is inhibited. Further, when the check valve is in a closed state, an angle &thgr; formed by the direction of the urging force transmitted to the valve body and the pressure action direction X is set to be between 8 degrees and 45 degrees. Accordingly, it is possible to simultaneously realize a fluid path opening/closing function and a valve body vibration inhibition function.

Abstract: In a check valve of the present invention, when a pressure action direction of a fluid on a valve body is assumed to be X, a spring receiving surface that abuts with a seat surface that is at one end in an axial direction of the helical compression spring is made to incline with respect to a surface perpendicular to the pressure action direction X. Accordingly, an urging force of the helical compression spring on the valve body acts obliquely with respect to the pressure action direction X. Thus the valve body is pressed to a side wall surface when the valve is opened, and vibration of the valve body is inhibited. Accordingly, it is possible to embody the invention with an extremely simple structure in which the spring receiving surface is inclined with respect to the surface perpendicular to the pressure action direction X.

Abstract: The present invention relates to an automotive vehicle brake system with wheel slip control which is provided with a non-return valve, between a secondary and a primary circuit. Initially, both circuits are evacuated for filling the brake system with pressure fluid, and evacuation of the secondary circuit is effected by way of the valve that opens. The present invention teaches providing this valve with an additional device by way of which the opening pressure of the valve is automatically increased after filling the brake system with brake fluid. The opening pressure shall be increased at least to such an extent that the valve closure member remains in the closing position at least during normal operation of the brake system. It is achieved by this provision that the secondary circuit can be sufficiently evacuated for the purpose of being filled with brake fluid, without a vacuum being generated later in the secondary circuit during a braking operation.

Abstract: A hydraulic brake system for a vehicle for braking the vehicle by brake pedal actuation and/or automatic braking. A pump is provided which has a suction connection that communicates with a supply container for a pressure fluid and a pressure connection for aspirating pressure fluid from the supply container and pumping the fluid to a connection of a master cylinder. A brake circuit of the vehicle brake system is connected with vehicle wheels associated with wheel brake cylinders and with valve assemblies for brake pressure modulation and is connected to the connection of the master cylinder. A valve pressure is also provided between a pressure chamber that communicates with the connection of the master cylinder and the supply container for pressure fluid.

Abstract: A solenoid valve for an anti-lock brake system is disclosed in which two orifices and oil passages are formed utilizing a valve seat and a piston. The solenoid valve includes a magnetic core (130) mounted in a bore (101) formed on a modulator (100), a plunger (140) movably mounted in the magnetic core (130), a valve seat (150) disposed below the magnetic core (130) in the bore (101), and a piston (200) movably mounted at the periphery of the valve seat (150). The valve seat (150) has an invariable orifice (320) formed at the inner middle portion of the valve seat, an inlet and outlet passages (300) and (310) formed below and above the invariable orifice (320), respectively. The piston (200) has a variable orifice (340) formed passing through one side of the upper portion of the piston. A lip seal (400) is provided between the outer periphery of the piston (200).

Abstract: A brake force control valve for use with an electrically controlled braking system having a housing with first and second fluid channels, a coil coupled to the housing, a ferrous core magnetically interacting with the coil, a spool coupled to the ferrous core, where the spool in conjunction with the housing forms a compression volume, a plurality of seals to fluidly seal the compression volume and where the coil is energized and deenergized to move the spool back and forth, the spool varying the volume of the compression volume to create positive pressure, thereby creating a pumping action.

Abstract: A hydraulic Control unit of a vehicular brake system includes a housing having a bore formed therein. A normally closed solenoid valve is retained in the bore of the housing. The solenoid valve includes a primary valve and a pilot valve, wherein a cross section of the primary valve is greater that a cross section of the pilot valve. A spring cooperates with the pilot valve so that the pilot valve is open when the primary valve is open.

Abstract: A barrier valve including an armature, longitudinally movable toward a pole core by excitation of an electrical winding. A prestressed compression spring in a longitudinal bore of the armature, as well as a support body, loaded by the compression spring, that is braced on a shoulder of the bore. The barrier valve furthermore has a tappet, which engages the support body and is movable relative to the armature and carries a closing body of a seat valve. When the winding is excited, the closing body is movable, overcoming the valve stroke, toward a valve seat of the seat valve. When the winding is excited, the closing body can be lifted from the valve seat by hydraulic forces acting on the closing body toward the valve seat, counter to the spring force of the compression spring in the armature. The stroke of the tappet relative to the armature engaging the pole core is limited to an amount less than the valve stroke.

Abstract: To improve the steerability and the driving stability of a vehicle during cornering, the standard control mode is replaced by a special or curve control mode in such a situation in an anti-lock system. This special control mode reduces the brake pressure on the wheel at the inner side of the curve. When, during a braking operation and with the special control mode activated, there is a transition from cornering to straight travel, the pressure deficit on the wheel at the inner side of the curve which is caused by the special control mode is compensated by a special pressure increase mode, for example, by compressing the pressure increase pulse row.

Abstract: In order to improve the control behavior of an ABS control system wherein, instead of the standard control mode, a special control mode or rather corner control mode comes into operation when a cornering situation is identified, said special control mode or corner control mode causing a reduction of the braking pressure on the front wheel and/or on the rear wheel on the inside of the corner, the gradient of the braking pressure build-up on the wheel on the inside of the corner is reduced in the partial braking range when a threshold value (th1, th2) of a wheel speed difference (SD) is exceeded, which difference is the difference between the wheel speed sums per side formed from the wheel speeds of the two wheels of one side of the vehicle, the reduction taking place in dependence on the extent by which the threshold value (th1, th2) is exceeded.

Abstract: A hydraulic brake system which incorporates several mutually independent brake circuits and does not require additional energy for conducting brake-slip control actions or stability control actions.

Abstract: A vehicular brake system having vehicle stability management includes a hydraulic master cylinder connected to wheel brakes via brake conduits. A pump generates fluid pressures and pressure control valves located between the master cylinder and the wheel brakes regulate the fluid pressures at the wheel brakes to achieve ABS and traction control. A medium pressure accumulator stores fluid pressurized by the pump which is supplied to the wheel brakes via associated control valves to achieve VSM braking control. The brake system has low power requirements because the medium pressure accumulator does not have to be filled quickly, yet the stored pressurized fluid can be released to the wheel brakes to quickly produce the braking pressures necessary for initiating most VSM applications. The pump is used to supplement the accumulator pressures to achieve full VSM control.

Abstract: A hydraulic automotive vehicle brake system with wheel slip control includes at least one non-return valve with a closure member that is lifted from its valve seat during evacuation of the brake system. An elastomeric sealing element is arranged between the closure member and the valve seat member.

Abstract: A vehicle brake system which permits both anti-lock control and different controls of independent force braking operations. In an independent force braking operation, a starting brake pressure is built up in the return circuit in the wheel brakes by way of a precharging pressure generator and the pump and is modulated in the following control phase according to the control algorithms of the selected control. Interposed between the precharging pressure generator and the return pump is a change-over valve which has three switching positions, i.e., one closed, one open, and one throttled. The change-over valve adopts its open position in the filling phase and its throttled position in the control phase. It is so configured that the switching position is achieved as a function of the initial pressure in the inlet chamber but independently of the actuating force which actuates the valve.

Abstract: A park brake release apparatus includes a service brake valve assembly operably connected to a service brake piston. A one-way valve is operably connected between the service brake piston and a park brake piston to allow fluid to flow from the service brake circuit to the park brake piston to release a park brake.

Abstract: An actuation unit for an electronically controlled hydraulic vehicle braking system, comprising a brake booster which can be actuated by a brake pedal and which comprises a master cylinder and a reservoir for hydraulic fluid, a first brake which is coupled with at least a first vehicle wheel and which is connectable with the master cylinder via an electronically controlled valve arrangement in a basic position or, in an actuation position is disconnectable from same, a brake pedal behaviour simulator which is connectable with the master cylinder and comprises a spring arrangement adapted to act against the hydraulic pressure from the master cylinder, and with which a characteristics modeling is associated.

Abstract: A slip-controlled hydraulic vehicle brake system having brake lines that extend between a dual-circuit master cylinder and a respective wheel brake cylinder. A shutoff valve in the respective brake line. A bypass line that bypasses the respective shutoff valve. A pump in the respective bypass line for pumping pressure fluid, drawn from the associated wheel brake cylinder to the master cylinder. The pump (30) is also embodied to feed pressure fluid from the master cylinder to the wheel brake cylinder. The pump is a recirculating positive-displacement vane cell pump. The pump in the bypass lines has a common drive motor whose rotational direction can be reversed. The vehicle brake system is embodied for anti-lock and traction control operation at no additional expense for equipment.

Abstract: A magnet valve with low noise upon shutoff from the pressure limiting function. The magnet valve has a two-part valve tappet, whose inner valve tappet part has the closing member of a seat valve. The closing member is circumferentially engaged in spaced-apart fashion, forming a gap space, by a tubular portion of the outer valve tappet part. From the gap space, a pressure fluid conduit leads to a control chamber, which is located between the face end, remote from the seat valve, of a magnet armature that cooperates with the valve tappet, and a valve dome. Upon shutoff of the magnet valve, the seat valve changes from its closing position to a partly open position, in which dynamic pressure in the gap space becomes operative and is transmitted through the pressure fluid conduit into the control chamber. The hydraulic force that is operative there on the magnet armature acts counter to the opening forces of the magnet valve and slows down its opening motion.

Abstract: A slaved dump valve for an anti-lock brake system having two driven rear wheels and traction control includes a check valve and restrictor. In particular the dump valve includes a 2-way/2-position solenoid valve connected to the return conduit of each rear wheel brake cylinder for reducing the pressure at both of the wheel brake cylinders simultaneously. Each return conduit of each rear wheel brake cylinder connected to the slave dump valve contains a check valve oriented to prevent pressurized fluid from flowing from one rear wheel brake cylinder to the other. A restrictor is positioned in each return conduit to allow the pressure at each of the rear wheel brake cylinders to be reduced immediately when the dump valve is opened. Fully independent pressure regulation of the rear wheel brake cylinders connected to the single dump valve can be simulated by controlling inlet valves in conjunction with the single dump valve.

Abstract: An apparatus and method for enhancing recovery of oil from producing and dormant wells. The invention is embodied in an apparatus in which brine is mixed with a small amount of oil, and then passed through an alternating current flowing between a pair of spaced apart electrodes. The invention is also embodied in a method which shutting in the second well, injecting hydrogen, hot water and steam into the formation via the first well, monitoring formation pressure at the second well until a pressure increase is detected, and recovering fluids including petroleum from said formation via the second well.

Abstract: A supply valve for use in a vehicular braking system includes a housing. A sleeve is disposed within a bore in the housing. A piston is slidably disposed within the bore. A valve element is disposed within the sleeve and includes a valve seat and check element for sealing against the valve seat to close the valve element. A lip seal is disposed on the sleeve for allowing fluid to flow from a low pressure accumulator to a pump, but not in the opposite direction. The supply valve is particularly adapted for use in an anti-lock braking system equipped with traction control.

Abstract: To improve the control behavior of an anti-lock control system or brake slip control system, more particularly, to improve the steerability of a vehicle and its drivability when braking during cornering is performed, criteria for cornering identification and for determining the direction of cornering are derived from the wheel slip of the individual wheels. When cornering is identified, the normal control mode which is intended for straight travel and is configured for an individual control of all wheels or an individual control of the front wheels in conjunction with a select-low control of the rear wheels is changed to a cornering control mode. In the cornering control mode, the average pressure level of the curve-inward front wheel is decreased by a predetermined value and the average pressure level of the curve-outward front wheel is increased by a predetermined value.

Abstract: Hydraulic pressure control apparatus wherein a pressure difference across a seating valve disposed in a fluid passage acts on a valve member for placing the seating valve in an open state, while an elastic member biases the valve member for placing the seating valve in a closed state, and a valve driving device operated with an electric current applied thereto generates a drive force acting on the valve member so as to open the seating valve. A control device for controlling the electric current includes a stepping controller for incrementing the amount of the electric current when the seating valve is operated from the closed state into the open state, such that an increment of the electric current decreases with an increase in the pressure difference. The hydraulic pressure control apparatus may be suitably used in a vehicle braking system, for controlling fluid pressure in wheel brake cylinder.

Abstract: The present invention is directed to a hydraulic pressure control system for controlling a hydraulic pressure in each wheel brake cylinder operatively mounted on each wheel of a vehicle, which includes a modulator disposed between a master cylinder and the wheel brake cylinder for introducing thereto and draining therefrom the brake fluid. First and second pump devices are provided for introducing the brake fluid and pressurizing it to discharge the pressurized brake fluid to the wheel brake cylinder through the modulator, respectively. The second pump device has a different suction phase from the suction phase of the first pump device.

Abstract: A hydraulic brake control apparatus in which a master cylinder is connected to wheel cylinders via a master cylinder cut valve, and the wheel cylinders are connected to a reservoir tank via a switching valve, includes a check valve provided between the master cylinder and the wheel cylinders in parallel with the master cylinder cut valve, the check valve provided in a bypass passage of the master cylinder cut valve, the check valve allowing a flow of a brake fluid from the master cylinder to the wheel cylinders and inhibiting a flow of the brake fluid from the wheel cylinders to the master cylinder.

Abstract: First and second directional control valves are respectively structured by directional control valves which are operable when skids occur in a wheel and are switchable to only a communication position or to an interrupting position, which enhances switching speed and anti-skid control speed. One end of a main fluid passage is coupled to a wheel cylinder by way of a second directional control valve which is switchable to a communication position or to an interrupting position, and is normally positioned at the communication position. One end of a pressure reduction fluid passage is coupled to the wheel cylinder by way of a first directional control valve which is switchable to a communication position or to an interrupting position, and is normally positioned at the interrupting position.

Abstract: The invention relates to a hydraulic unit for a vehicle brake system with ABS. Before being filled with brake fluid, the brake system must be evacuated in order to achieve complete bleeding. In order to evacuate a return line, which is separated from a brake line by pressure reduction magnet valves that are closed in their position of repose, it is known to provide a connecting line with a check valve between the brake line and the return line. The hydraulic unit connects the check valves in parallel to the magnet valves and integrates the check valves with the magnet valves. This simplifies assembly. Since no additional holes and conduits in the hydraulic unit are necessary, existing hydraulic units can be used.

Abstract: An anti-lock braking control system for use in vehicles contains a restrictive orifice associated with an attenuator in the master cylinder brake line and opposed, parallel check valves positioned parallel to and independent of the restrictive orifice, all of which is located at or upstream of the juncture of the pump outlet line, thus allowing high volume fluid flow to and from the master cylinder while providing high pressure pulse and vibration damping of the ABS/TCS pump and associated isolation valve, and isolating this from the master cylinder and from operator pedal feel. Preferably, the reduced size orifice comprises one or more grooves located in the conical seat of at least one and preferably both check valves, which are preferably of the check ball type. Alternatively, a traditional, generally circular cross-section restrictive orifice in parallel with the check valves, may be substituted for or used in conjunction with the aforementioned grooves or their equivalents.

Abstract: In a power-brake system, a hydraulic pressure generated by means of a pump may be supplied, controllably in proportion to an actuation force via brake conduits, by a power-brake valve to individual brake cylinders. Control pressure conduits are connected to the brake cylinders or the brake conduits in the vicinity of the brake cylinders and these control pressure conduits are connected to the brake valve. The brake pressure at the brake cylinders may be fed back, via the control pressure conduits, as the control pressure for acting on the control end of the brake valve so that a control of the control plungers of the brake valve is carried out corresponding to the brake pressure build-up at the brake cylinders and, particularly when low brake pressures are desired, rapid pressure build-up times in the brake conduits are ensured.

Abstract: An anti-lock hydraulic brake system comprising a master cylinder and a wheel brake, with a flow control valve being inserted into the brake line. A non-return valve is inserted into the brake line. A direct connection is established between the wheel brake and the master cylinder, with a non-return valve opening towards the master cylinder. A pump supplies fluid into the brake line between the non-return valve and the flow control valve. A high-pressure accumulator is provided on the pressure side of the pump.

Abstract: An ABS hydraulic modulator suitable for vehicular applications is provided. The design utilizes an electric motor which powers a hydraulic pump unit used to recirculate brake fluid during ABS operation. The hydraulic circuit components also include a normally closed ABS release solenoid valve, an integral spring-loaded piston accumulator, an isolation valve and check arrangement, a number of strategically placed flow control orifices and an optional hydraulic damper assembly.

Abstract: A process of assembling an electromagnetic valve in which a gap provided between a core and a plunger can be maintained properly without an increase in a number of parts or deterioration in assembly performance. The electromagnetic valve has a shaft, a valve element, which opens and closes a channel, being provided at an end portion of the shaft; a plunger fixed to another end portion of the shaft at the opposite side of the valve element; a valve seat forming body which is positioned further toward the valve element than the plunger, the valve seat forming body forming a valve seat at which the valve element is set; and a sleeve which provided at a periphery of the plunger, a core which opposes the plunger being fixed to the sleeve, and the sleeve being fixed to a housing by caulking.

Abstract: In a hydraulic brake system for a vehicle, the brake fluid in a first wheel brake and the brake fluid in a second wheel brake which are hydraulically connected to a pressure generating chamber of a master cylinder are individually caused to flow into a low back pressure reservoir with the aid of an electromagnetic change-over valve and first and second electromagnetic cut-off valves; and with a pump driven by an electric motor, the brake fluid flowing in the low back pressure reservoir in the above-described manner is caused to flow through a first check valve and a first orifice to the first wheel brake, and through a second check valve and a second orifice to the second wheel brake. With the pump operated, the first and second electromagnetic cut-off valves are individually operated, so that the first and second wheel brakes are individually decreased or reincreased in hydraulic pressure. For traction control, electromagnetic change-over valves provided in bypass passages are operated.

Abstract: A brake pressure controller for a hydraulic vehicle brake system includes a master brake cylinder (1), a wheel brake cylinder (10, 11) connected thereto through a brake conduit (5), and a branch conduit (8, 9) which is provided in the brake conduit (5) between the master brake cylinder (1) and the wheel brake cylinder (10, 11). The brake system includes control valves (12, 14) and a pump (16) returning pressure fluid from a return conduit (15) into the brake conduit (5). At least one valve (6) is provided between the master brake cylinder (1) and the branch conduit (8, 9), which valve, in a first mode of operation, connects the outlet (17) of the pump (16) to the master brake cylinder (1) and, in a second mode of operation, discontinues the connection from the outlet (17) of the pump (16) to the master brake cylinder (1) and connects the inlet (24) of the pump (16) to the master brake cylinder (1) or a reservoir (4).

Abstract: An electromagnetic valve that is easily manufactured and has a coaxially adjustable valve seat thereby allowing customized selection of valve components. A precise adjustment of the aial air gap is permitted on the hold-on magnet. An individual selection of a diaphragm member situated within a valve seat member is provided for with the diaphragm member being detachably connected to the valve seat member and with the diaphragm member having an outwardly flared open end.

Abstract: A brake fluid pressure control apparatus includes a second pump communicating port disposed to face a first pump communicating port approximately perpendicularly to the direction of movement of a spool. The first and second pump communicating ports are connected to a master cylinder, and a check valve is provided between the master cylinder and the first and second pump communicating ports. The check valve is adapted to open when the master cylinder-side brake fluid pressure becomes a predetermined value higher than the pump discharge-side brake fluid pressure. A master cylinder communicating port is provided to extend along the direction of movement of the spool. A cut-off valve is provided between the master cylinder communicating port and the master cylinder. The cut-off valve is closed when the spool is moved to provide communication between the pump communicating ports and a wheel cylinder communicating port.

Abstract: A hydraulic brake system that has a hydraulic unit for evacuation prior to initial filling, with the primary and secondary circuits dry, the brake system is equipped with special check valves, which are disposed between the primary circuit and the secondary circuit. When the brake system is evacuated, these check valves are in the open position, so that air escapes from the secondary circuits. This makes it unnecessary to open electromagnet valves, which are closed when without current and are present in the brake circuits I and II, electrically. The hydraulic brake system is intended for use in motor vehicles, and its hydraulic unit is designed to carry out anti-lock operation and/or traction controls.

Abstract: A brake force control device for a vehicle includes a master cylinder for being operated by an operating member of the vehicle, a wheel brake for being mounted on a vehicle wheel which is connected to the master cylinder through a conduit, a pressure control chamber connected to the wheel brake, a displacement actuator which varies a capacity of the pressure control chamber and a control unit which controls the displacement actuator.

Abstract: A brake pressure controller for a hydraulic vehicle brake system includes a master brake cylinder (1), a wheel brake cylinder (10, 11) connected thereto through a brake conduit (5), and a branch conduit (8, 9) which is provided in the brake conduit (5) between the master brake cylinder (1) and the wheel brake cylinder (10, 11). The brake system includes control valves (12, 14) and a pump ( 16) returning pressure fluid from a return conduit (15) into the brake conduit (5). At least one valve (6) is provided between the master brake cylinder (1) and the branch conduit (8, 9), which valve, in a first mode of operation, connects the outlet (17) of the pump (16) to the master brake cylinder (1) and, in a second mode of operation, discontinues the connection from the outlet (17) of the pump (16) to the master brake cylinder (1) and connects the inlet (24) of the pump (16 ) to the master brake cylinder (1) or a reservoir (4).

Abstract: An anti-lock hydraulic brake system is disclosed with a flow control valve in the brake line. To prevent the flow control valve from performing its control function during a normal braking operation, a retaining piston works in conjunction with a spring such that the retaining spring bears against a piston of the flow control valve and retains the flow control valve piston in its initial position during normal braking operation. The retaining piston also serves as a valve closure member for a valve in the return line.

Abstract: A vehicle antilock braking system having an operator controlled master cylinder for developing a first source of pressurized fluid and a second source of pressurized hydraulic fluid for selectively supplying rebuild pressure after an antilock event to simultaneously provide for actuation of each wheel braking device. A solenoid operated first flow control valve for each wheel controls communication of either the first source or second source of pressurized hydraulic fluid to the braking device and the braking device to a low pressure return. A hydraulically operated second control valve has a first inlet port connected to receive the first source of hydraulic pressurized fluid and a second inlet connected to receive the second source of hydraulic fluid and an outlet port connected to the first flow control valve.

Abstract: An electronic pressure relief system for a traction slip control vehicle brake system maintains the pressure within the brake system at its desirable level by electronically controlling an isolation valve coupled to the brake conduit. The isolation valve is controlled by supplying an energizing current to the valve at a preselected level such that the holding pressure exerted by the valve is maintained at a level approximately equal to the maximum desired pressure level to be maintained within the brake conduit during the traction slip control maneuver.

Abstract: A known electromagnetically actuatable valve has a tubular housing sleeve, a through opening radially penetrating the housing sleeve, and inside the housing sleeve, a valve body having a valve seat and an associated movable valve closing member, and a throttle, which comprises a throttle body and a throttle insert built into it having a throttle restriction, which is embodied as a throttle bore. The throttle body is slipped on like a cap over an open end of the housing sleeve. The throttle of this kind, embodied in a complex manner, is expensive and demands an inordinate amount of installation space. To reduce expense and save installation space, the throttle body along with its throttle insert is omitted and the function of the throttle bore is taken on by the through opening, the through opening is embodied as narrow opening in accordance with the throttle function to be produced. The valve can be used in antilock devices of hydraulic brake systems for motor vehicles.

Abstract: An antilock modulator can maintain a short brake pedal stroke during normal braking operations, which improves the pedal feeling during antilock control, and can prevent unnecessary increases in the pump discharge pressure. The antilock modulator has a main fluid line connecting the wheel brake to the master cylinder and a line branching from the main fluid line and leading to the discharge end of the hydraulic pump. At the branching point is provided a differential pressure-responsive mechanism which shuts off fluid communication between the master cylinder and the discharge end of the pump when the pressure difference between the wheel brake and the master cylinder exceeds a predetermined value, and otherwise allows fluid communication therebetween.

Abstract: A hysteresis control valve (10) is disposed between a master cylinder and a wheel cylinder. The hysteresis control valve comprises a first stepped piston (12) fixed within a cylinder bore (11a) and including a bypass bore (12b) communicatable with the wheel cylinder, a second stepped piston (13) slidably mounted within the cylinder bore (11a) and having at its one end a valve body (14) opened under a given pressure to prevent communication through the bypass bore 12b, and a cup seal (15) disposed between the outer periphery of the first stepped piston (12) and the inner periphery of the cylinder bore (11a).

Abstract: A wheel brake fluid pressure control device has a main fluid line and a return-flow type antilock control function. This device also has a fluid supply line branching from the main fluid line so that it has a traction control function as well. It is necessary to provide such a device with a shutoff valve for checking the fluid flow from the fluid supply line to the discharged fluid reservoir while the master cylinder is being pressurized. The shutoff valve employed is not an expensive solenoid valve or a pressure-responsive valve, but a pressure-responsive type check valve which closes when the brake pressure in the discharge line exceeds a predetermined level. This shutoff valve is simple in structure and low in cost and can improve the reliability of the entire device. Also, by using this valve, the traction control function can be added to an existing antilock control device at a low cost.