Abstract: An improvement of a reaction transmitting mechanism for a booster is disclosed. A spring charged to a preset load is disposed between a stepped end face of value body and a plunger plate to urge the latter forwardly. This separates the plunger plate and a value plunger from each other in the inoperative condition of the booster. As an input shaft is driven forward to operate the booster, a reaction disc bulges into abutment against the plunger plate. Subsequently when the spring is compressed, the plunger plate abuts against the value plunger, which defines a jumping point. From this point on, a reaction from the output is transmitted to a driver. Since the output upon the jumping is determined by the preset load to which the spring is charged, a variation in the output upon jumping is minimized for any variation in the hardness of the reaction disc.

Abstract: A variable capacity pump includes a rotor, a plurality of vanes, a cam ring, a spring, a variable orifice, first and second fluid pressure chambers, and first and second openings. The spring biases the cam ring to a position where a volume of the pump chamber of a portion ranging from a pump suction region to a pump discharge region becomes maximum. The variable metering orifice is formed midway along a discharge passage of a pressure fluid discharged from the pump chamber. The first and second fluid pressure chambers are formed between the outer circumferential portion of the cam ring and the inner circumferential surface of the pump body to be divided in a biasing direction of the cam ring, and swing the cam ring upon introduction of input and output fluid pressures of the metering orifice thereto. The first and second openings respectively open to the pump suction region and the pump discharge region of the pump chamber to have opening areas that are changed by a swing of the cam ring.

Abstract: A brake booster includes a reaction transmitting means which includes a spring that is compressed when a brake reaction from a reaction disc exceeds a preset load. A holder is mounted on a valve body, and a brake reaction which is transmitted from the reaction disc is accepted by the valve body through the holder. A plate plunger is slidably fitted in the holder to allow a brake reaction which is transmitted to the reaction disc to be transmitted to the reaction transmitting means and the valve plunger through the plate plunger. A larger outer diameter can be chosen for the spring in order to achieve a preferred preset load, and a servo ratio can be freely established by the choice of areas of contact between the reaction disc on one hand and the holder and the plate plunger on the other hand.

Abstract: In a brake-pressure producing device of the present invention, a power piston 10 of a hydraulic booster 2 comprises a stepped piston including a large-diameter portion 10a on which fluid pressure of a power chamber 30 is exerted and a small-diameter portion 10b having the same diameter as the master cylinder piston 53. Both the pistons 10, 53 are interlocked with each other through an aligning rod 62. The pressurized fluid of the power chamber 30 is introduced into an annular chamber 51 formed on the circumference of the small-diameter portion 10b and the fluid pressure of the pressurized fluid is exerted on a stepped portion 10c between the large-diameter portion 10a and the small-diameter portion 10b in the direction opposite to the direction of the fluid pressure of the power chamber 30.

Abstract: The present invention discloses a master cylinder MC, which comprises a body section 2, a cap 3, a cylinder housing 1 composed of the body section 2 and the cap 3, a sleeve 8 fitted in the cylinder housing 1, primary and secondary pistons 4 and 5 provided to be guided by the sleeve 8 and slid, first and second pressure chambers 9 and 10 and spring mechanisms 11 and 12 respectively disposed in the first and second pressure chambers for pressing the primary and secondary pistons 4 and 5 in returning directions. In the peripheral portion 17a of the spring retainer 17 of the spring mechanism 11 for pressing the primary piston 4, hook sections 17e are formed by protruding a plurality of portions 17d outward in an axial direction and then folding the tip of each of the protruded portions in a piston axial direction so as to hook the same in the outer peripheral surface of the sleeve 8.

Abstract: In a hydraulic brake system of the present invention, the communication between a power chamber 30 of a hydraulic booster 2 and wheel cylinders (WCY) 58, 59 is allowed by a switching valve 64 when fluid pressure of an accumulator (ACC) 46 exceeds predetermined pressure. During braking operation, the fluid pressure of the ACC 46 introduced in the power chamber 30 is introduced directly to the WCYs 58, 59, thereby rapidly actuating brakes and thus improving the response. When the fluid pressure of the ACC 46 is less than the predetermined pressure, the communication between a fluid chamber 57 of a master cylinder (MCY) 3 and the WCYs 58, 59 is allowed by the switching valve 64. During braking operation, MCY pressure developed by a MCY piston 53 operated by an input shaft 21 through a power piston 10 is introduced into the WCYs 58, 59 through the switching valve 64. The brakes can securely work even when the fluid pressure of the ACC 46 is less than the predetermined pressure.

Abstract: The invention relates to a connection structure between a brake booster and a control valve which selectively introduces a negative pressure or an atmosphere into the booster. A brake booster of tandem type includes a front shell on which a pair of bosses are connected so as to extend parallel to each other. One end of one of the bosses is connected to a housing of the control valve while one end of the other boss is connected to the housing of the control valve through an L-shaped connection pipe. One end of the L-shaped connection pipe is rotatable with respect to one end of the other boss, and the other end of the L-shaped connection pipe is displaceable axially of the engaging opening in the housing during assembly. This construction allows the control valve to be assembled into the brake booster without requiring undue demand on the precision of the manufacturing various parts, while also minimizing the space required for the connection pipe.

Abstract: An electric motor for driving an oil pressure pump which feeds pressurized oil to a power cylinder comprises a brushless d.c. motor. An onboard main battery comprises a main battery which is onboard an electrically driven vehicle and which is constructed as a high tension d.c. voltage source delivering a high voltage on the order of 96 to 600V. The battery is directly connected to the motor, and a controller is connected therebetween to provide a pulse width modulated variable voltage signal to the motor from the battery.

Abstract: An improvement of a booster as may be used in a brake of an automobile is provided. The booster is provided with pseudo-reaction imparting means (spring) which imparts a pseudo-reaction which depends on the travel of an input shaft to the input shaft. An arrangement is made in accordance with the invention such that when an input applied to the input shaft exceeds a given value, only the pseudo-reaction from the pseudo-reaction imparting means (spring) is transmitted to a driver. The arrangement enables an increased output to be reliably obtained, even by a powerless female driver, whenever a braking force of an increased magnitude is required as when using the booster as an emergency brake.

Abstract: According to the invention, a first spring abutment which extends radially outward is formed on a valve plunger, which forms part of a reaction mechanism for brake booster. A second spring abutment which extends radially outward is formed on a plate plunger. A plurality of coiled springs are disposed in parallel across the pair of spring abutments, and a brake reaction is transmitted to the valve plunger through the plate plunger, the second spring abutment, the plurality of the coiled springs and the first spring abutment. With this construction, the plurality of coiled springs which are disposed in parallel provide a combined spring constant, which is given as a sum of spring constants of individual coiled springs, whereby a combined spring constant of an increased magnitude can be obtained. This allows a servo ratio of the brake booster while the plurality of coiled springs are being compressed to be freely chosen as compared with the prior art.

Abstract: A brake booster is disclosed which functions as an automatic brake as required. Bellows is disposed within a constant pressure chamber of the brake booster, and has a front end which is connected, by a first support member, to a bulge which is formed in the axial portion of a shell. A seal member is connected to the outer periphery of the first support member, and is held in abutment against the wall surface of the shell at a location radially outward of an inlet for the atmosphere. A communication channel is formed by a space between the first support member and an opposing wall surface of the shell and the bulge and the like. A communication is established between the internal space of the bellows and the inlet through the communication channel. This construction allows the overall length of the brake booster to be reduced as compared with the prior art in which a spacer is provided outside the shell.

Abstract: According to the invention, the booster is not provided with a brake reaction transmission mechanism, and hence a reaction cannot be transmitted to a brake pedal. On the other hand, a pseudo-reaction imparting means is provided to impart a pseudo-reaction of suitable magnitude which depends on the degree of depression of the brake pedal. The pseudo-reaction imparting means is arranged so that when the brake pedal is depressed relatively rapidly, a relatively smaller braking reaction is imparted than during a usual depression. With this arrangement, the transmission of an abnormally high braking reaction to a driver which is experienced in a conventional booster during a quick braking operation due to an operational rag of the booster is avoided.

Abstract: A valve plunger, which forms part of a reaction mechanism of a brake booster, comprises a plunger member and a valve side member which are disposed to be slidable relative to each other, with a first spring disposed therebetween. A piston is slidably disposed within a valve body, and a given clearance is formed between the rear end face of the plunger member and the piston. A second spring having a greater resilience than the first spring is disposed between the piston and the valve body, and is compressed after the first spring is initially compressed. With this construction, as a brake reaction increases, the first spring is compressed to cause the plunger member to abut against the piston, and subsequently the first and second spring are compressed.

Abstract: A control valve is disclosed which is capable of supplying a required control pressure to an actuator such as a brake booster, for example. The control valve includes a valve mechanism within a housing, and the valve mechanism comprises a piston which is associated with a solenoid. When the solenoid is excited, the piston is driven for movement to switch a flow path within the housing. In this manner, the atmosphere, acting as a control pressure, is introduced into a variable pressure chamber defined within the housing. The atmosphere which is introduced into the variable pressure chamber is arranged to push back the piston, so that a control pressure which depends on the magnitude of a current passing through the solenoid can be generated within the variable pressure chamber. As compared with a prior art arrangement, the control valve of the invention reduces the cost of the entire arrangement, and allows a piping arrangement for pressure fluid to be simplified.

Abstract: An electronic controller of the invention judges whether the pedaling speed exceeds a threshold and a pedal pressure exceeds a threshold based on detected signals from a stroke sensor and a pressure sensor. When the electronic controller judges that the pedaling speed exceeds the threshold and the pedal pressure exceeds the threshold, comparators output signals to actuate a switch. Thus, a braking force for emergency braking is outputted.

Abstract: An improvement of an output shaft of a booster is disclosed. An output shaft 23 is formed by a push rod 24 and an adjusting screw 25. The push rod 24 is formed with an axial bore 26 in its distal end, the axial bore including a portion 26b of a reduced diameter which is less than an outer diameter of a threaded section 25C of the adjusting screw. The threaded portion is formed as a self-tapping screw. The adjusting screw includes a guide 25D at a location which is initially inserted into the axial bore before the threaded portion is inserted into the threaded portion. The guide comprises a plurality of annular projections 27 having an outer diameter which is substantially equal to the inner diameter of the axial bore. With this construction, when the guide 25D is fitted into the portion 26b of the axial bore 26 which has a reduced diameter, the axis of the adjusting screw 25 may be brought into alignment with the axis of the push rode 24.

Abstract: A vehicle power steering system for controlling an assist force which supplementally supports the steering operation, includes a motor for producing the assist force, a battery for supplying a current to the motor, a speed sensor for detecting a vehicle speed, a steering-wheel angle sensor for detecting an angle of a steering wheel, a circuit for adjusting the current fed from the battery to the motor according to the vehicle speed detected by the speed sensor and the angle of the steering-wheel detected by the steering-wheel angle sensor, a booster inserted in a current feed path to the motor for boosting a battery voltage of the battery to apply a boosted voltage to the motor. The vehicle power steering system further may include a boosted-voltage stabilizer for controlling the boosted voltage to a predetermined value through an operation of monitoring the boosted voltage.

Abstract: A vehicle speed responsive power steering apparatus enables a pressure which acts upon a power cylinder to be variably controlled in accordance with a vehicle speed or the like, thus allowing an assisting force to be controlled in a variable manner. A control valve CV selectively connects a pump P and a tank T to left and right chambers CL, CR of a power cylinder. The control valve comprises a first and a second fluid pressure bridge circuit 10, 20. The first fluid pressure bridge circuit includes a left and a right path 12, 13, in which a first and a second pair of variable throttles 1R, 1L and 2L, 2R are disposed which are opened or closed in response to a steering operation. The left and the right chamber of the cylinder are connected to the respective paths at the junctions between the variable throttles.

Abstract: A valve seat (50) is provided on and along the end face of the end tubular portion (16a) of the valve body (16) of a power brake device. A valve member (49) is slidably put on the input shaft (8). The valve member (49) is moved forward and backward by an actuator (51). When the valve member (49) is seated on the valve seat (50), the valve member (49) closes a pressure path (35). In this state, the operation of amplifying a braking force by the power brake device is not performed. The brake system may be incorporated into a vehicle with a regenerative brake device. The operation of amplifying a braking force by the power brake device can be interrupted. Therefore, the brake system produces a braking force optimal for a current loading state of a vehicle. The braking force amplifying operation of the power brake device can be stopped until the regenerative brake device produces a large regenerative braking force. Therefore, the regenerative braking force can be effectively used.

Abstract: A electric motor, which drives a fluid pressure pump used to derive a steering assist force, is controlled in a required manner using a simplified arrangement. Specifically, a pump 11 which feeds a fluid pressure in order to produce an assist force is driven by a D.C. brushless motor 11 which is provided with means 18 for detecting a rotational position of a rotor 23 thereof. Motor control means 14, 15 drives and controls the motor to rotate at a given number of revolutions. Vehicle speed detecting means 16 detects a running speed of a vehicle. The motor control means controls the number of revolutions of the brushless motor on the basis of information representing a vehicle speed, a number of revolutions of the rotor which is determined by utilizing a signal from the rotor position detecting means, and information from means which detect a steer angle and a steering angular rate.