Showing papers on "Dynamic braking published in 1991"

Braking force control apparatus

Abstract: The braking forces applied to the left and right wheels of the vehicle are controlled to provide a target yaw rate calculated based upon a sensed steering angle and a sensed vehicle speed. For this control, a target difference between the braking forces applied to the left and right wheels is calculated from a model specifying the target braking force difference as a function or functions of target yaw rate, steering angle, and vehicle speed. The model is obtained from equations of motion of the vehicle. The calculated braking force difference is used to set the braking forces to be applied to the left and right wheels by means of valves 3FR, 3FL. The controller 16 receives inputs from a steering sensor 11, vehicle speed sensor 12, pressure sensors 14, a brake switch 13 and optionally a longitudinal acceleration sensor.

Method of shortening the braking distance in critical driving situations by sensing brake pedal speed

Abstract: A method of shortening the braking distance in critical driving situations uses the criterion of exceeding of a first threshold value by the actuating speed of the brake pedal (vBP) by the vehicle driver for initiating an automatic braking operation. A brake pressure (pB,max) which corresponds to the value of the brake pressure with optimum deceleration of the vehicle is built up automatically immediately after initiation of the automatic braking operation.

Motor vehicle brake system with fail-safe mechanism

Abstract: An electric brake system for a motor vehicle has a plurality of braking force generating mechanisms associated with respective road wheels and including electronic actuators mechanically separate from a brake pedal. In the event of a failure of at least one of the braking force generating mechanisms, the electric brake system selects and operates normal braking force generating mechanism or mechanisms for braking the motor vehicle stably with boosted braking forces. The braking force generating mechanisms are mechanically separate from the brake pedal and operable independently of each other. Failure detecting circuits are associated respectively with the braking force generating mechanisms, for detecting a failure of the braking force generating mechanisms and producing a failure signal representing the failure. The electric brake system includes a controller for controlling the braking force generating mechanisms in response to the signal from the brake pedal. The controller selects at least one of the braking force generating mechanisms to be operated based on the failure signal from the failure detecting circuit according to a predetermined rule.

Collision-preventing apparatus for electric motor vehicle

Abstract: A collision-preventing apparatus for an electric motor vehicle in which wheels are driven by electric motors and the electric motors are subjected to braking such as regenerative braking or dynamic braking. The apparatus includes an obstacle sensor and a control unit for processing detected information supplied from the obstacle sensor and for outputting a brake actuation signal when the result of processing indicates a set of conditions predetermined to be dangerous, so as to apply brakes to the electric motors.

Method for determining operability of an electrical dynamic braking system

Abstract: A method for determining operability of a dynamic braking system in an electrically propelled traction vehicle by cycling selected switching devices while the vehicle is at rest and measuring voltages and currents generated in response to operation of the switching devices. In one form, the dynamic braking system is operated to be connected to a power conversion system of the vehicle and the voltage developed at the braking system compared to the voltage coupled to the vehicle. Using prior knowledge of system resistances, calculated ideal values of voltage are compared to measured values to confirm proper system operation. Malfunctions of particular components are logically determined by ratios of measured to ideal values and by operation of selected ones of the switching devices.

Method of distributing brake pressure to the axles of a motor vehicle with an abs pressure-medium brake

Abstract: A method utilizes components of an existing anti-lock brake system (ABS) in order thereby to achieve an automatically self-optimizing inter-axle brake-pressure distribution acting far below the wheel lock limit. For this purpose, the brake pressure and, hence, the brake-force distribution are regulated axle-specifically far below the wheel lock limit too. An immediate dynamic intervention is, on one hand, effected in the case of sufficiently large wheel-speed differences between the axles. On the other hand, an adaptive predetermination of correct brake-force distributions is made the basis for each current regulating intervention. Even before the occurrence of large speed differences, the brake-force distribution expedient in each case for these is here predictively determined, stored, and, if required, correspondingly adapted to current requirements, i.e. corrected, in the course of subsequent dynamic braking demands. Requisite determination parameters are obtained for each journey either via characteristic diagrams specific to the family of vehicles or are determined individually on the individual vehicle by a learning approximation routine.

Chopper circuit for dynamic braking in an electric power conversion system

Abstract: An improved electrical circuit configuration for a chopper circuit is disclosed which is particularly adapted for use with an inductive load such as a braking resistor of the type used in many rapid transit vehicles Instead of connecting a di/dt reactor directly in series with the electronic switch of the chopper circuit, a di/dt reactor is connected in series with the freewheeling diode Using this configuration, the di/dt reactor does not have to continuously handle the average current through the electronic switch during the entire chopping operation Hence, a much smaller, lighter, and less expensive di/dt reactor can be utilized

Eddy current drive dynamic braking system for heat reduction

Abstract: A dynamic braking means for a variable speed dynamoelectric eddy current drive consists of an ac motor (4) rotationally coupled through a shaft (6) to an inductor drum assembly (13) of an eddy current coupling (3), where an annular field coil 12 generates an electromagnetic field which couples the inductor drum assembly to a pole assembly (10) which is rotationally coupled to an output shaft (16) which drives an inertial load (20) Upon command to stop and brake, a controller (30) signals a motor switch (26) to disconnect the ac motor from the ac source and connect it to a dc source, causing a braking torque to be produced Concurrently, the controller signals a coupling switch (28) to go to an open position momentarily until the motor decelerates to approximately zero speed, whereupon the coupling switch is again closed, coupling the inertial load to the motor, thereby providing a braking action The major portion of dissipated kinetic energy is thus shifted from motor to coupler, which has a higher heat capacity

Hybrid drive system with regeneration for motor vehicles and the like

Abstract: A hybrid motor vehicle includes a storage battery providing motive power to an electric motor under the control of a microprocessor. A generator with an internal combustion engine may be used to charge the storage battery. The motor is operated either in an actuated mode in which current flows from the battery and a dynamic braking mode in which regenerated current flows from the motor to the battery. Electronic circuitry is used to insure that regenerative current is generated even if the motor Emf is lower than the voltage of the storage battery.

Optimal switching of dynamic braking resistor, reactor or capacitor for transient stability of power systems

Abstract: Three dynamic braking strategies for transient stabilisation of a power system have been investigated. These involve resistor, resistor-reactor and resistor-capacitor switching, respectively. The switching strategies are obtained from an optimum feedback control law. The proposed controls were tested on a four-machine power system. It was observed that although all the optimal strategies were able to contain the first swing instability, the resistor-capacitor switching was the best for electromechanical as well as electrical transients control.

Method for controlling hydraulic braking pressure for a vehicle

Abstract: According to the method of the present invention, when the vehicle speed has become less than the reference speed, after a reduction in the hydraulic braking pressure during braking, the hydraulic braking pressure is gradually increased. According to the above method, the rate of increase of the hydraulic braking pressure is moderated when the vehicle speed has become less than a reference value. This will avoid the degradation in braking feeling due to a rapid increase in hydraulic braking pressure for a wheel brake.

Brake controller for electric automobile

Abstract: PURPOSE:To correct imbalance of total brake force caused by the fact that the regenerative brake force under high speed is different from that under low speed CONSTITUTION:Hydraulic pressure is interrupted through a reducing valve 30 under high speed while through reducing valves 30, 32 under low speed Hydraulic brake functions when a differential pressure DELTAP exceeds the open valve level of the reducing valve 30 under high speed or when the differential pressure DELTAP exceeds the total open valve level of the reducing valves 30, 32 An ECU 16 performs regenerative braking of a motor 14 based on the differential pressure DELTAP Since hydraulic brake functions under low speed only when the differential pressure DELTAP is higher than that under high speed, overbrake is prevented under low speed

Locomotive dynamic brake control.

Abstract: An apparatus (10) for controlling dynamic braking in a vehicle having at least one drive motor (26) of the type having an armature and a field (27). The motor (26) is adapted to function as an alternator during dynamic braking for dissipating power through a resistor grid (38). The vehicle includes a field current controller (24) for regulating the level of dynamic braking by controlling the current level through the motor field (27). A brake level selector (76) is provided for producing a desired braking level signal. A field current sensor (64) senses the current level in the motor field (27) and produces an actual field current signal. A grid current sensor (68) senses the level of current flowing through the resistor grid and produces an actual grid current signal. A controller (10) receives the desired brake level signal, the actual field current signal, and the actual grid current signal. The controller (10) produces a first desired field current signal and a desired grid current signal in response to the desired brake level signal. The controller (10) further produces a second desired field current signal in response to the actual field current, actual grid current, and desired grid current signals, compares the first and second desired current field signals and produces a final desired field current signal responsive to the compared signals. The field current through the motor (26) is controlled in response to the final desired field current signal.

Electric vehicle control apparatus

Abstract: Disclosed is a control apparatus for an electric vehicle, and particularly the dynamic braking control in the event of ineffectual regenerative braking load. A dynamic braking chopper (14) is controlled at electric braking in at least three divided modes of stopping control, chopping control and full conduction control in correspondence to voltages of a filter capacitor (6). As a result, the electric braking operation can be shifted reversely from electric braking to regenerative braking, and vice versa, without opening a line breaker or applying an air brake even in the event of ineffectual regeneration and ultimate over voltage, whereby the domain of regenerative braking after the emergence of over voltage can be extended to the maximum, and consequently the torque variation can be suppressed and the operating life of such mechanical components as brake shoes and line breaker can be extended.

Vehicle braking signalling system - uses standard brake lights and auxiliary brake lights to provide complementary dynamic braking signals

Abstract: The signalling system provides complementary dynamic braking signals using auxiliary brake lights in addition to the normal rear brake lights. The braking signalling system is controlled via a microprocessor (5), evaluating signals supplied from acceleration, ambient light and temp sensors (1,2,3) via an A/D converter (4), its control outputs coupled to a power amplifier (10) and driver amplifiers (8, 9) for operating the signal lights (6). ADVANTAGE - Allows intensity of braking to be indicated.

Single handle locomotive controller

Abstract: A locomotive control system having a single handle movable between a maximum propulsion position, through diminishing propulsion positions, through a release/idle position, through increasing braking positions, through a full service brake position to an emergency brake position. The control system receives position signals from the handle and generates propulsion, dynamic braking and fluid braking control signals as a function of the position signals. For any braking position of the handle, the control system first applies or removes dynamic braking and then provides fluid braking depending upon the position of the handle, the type of train brakes and whether the dynamic braking has maximized or is zero.

Drive control system for vehicle - has failsafe braking if throttle control jams

Abstract: The vehicle is controlled by a throttle pedal (10) and brake pedal (20). The displacement of the controls is monitored and the displacement signals used to generate the control signals for the vehicle drive. A safety circuit (40) monitors the signals from the controls and operates a failsafe braking cycle if the throttle control jams. The failsafe braking cycle is release by re-applying the brake pedal and by operating the brake control more than a set amount. This ensures that the driver retains maximum control, despite a sticking throttle. ADVANTAGE - Improved drive control, failsafe braking.

Method and apparatus for controlling swing stop of upper swing body in construction machine

Abstract: Herein described is a method and apparatus for controlling braking and stopping of the slewing of an upper slewing body which is slewingably provided on a construction and hoists a load, represented by a rotary crane, wherein the braking torque for braking the upper slewing body and the braking torque for braking a hoisting load are separately obtained by the calculated slewing angular acceleration, and the whole braking torque is calculated on the basis of both the braking torques, thereby achieving a high accurate control of the slewing stop.

Brake light system for vehicle with antilock braking system - flashes brake lights on and off during heavy braking by using ABS pulse generator to control brake lights as well as braking force

Abstract: The anti-lock brake light system uses periodically flushing brake lights to warn following drivers. The periodic flashing of the brake lights takes place automatically in periodic relationship to the ABS effect. The pulse generator or oscillator used in the ABS-system to pulse the braking tone applied to the wheels is also used here to pulse the brake lights. During gentle braking, the brake lights remain on. During heavy braking when the ABS-system comes into operation, the brake lights are pulsed on and off. ADVANTAGE - To provide drivers following behind with warning that vehicle in front is braking strongly.

Vehicle antilocking braking system - evaluates wheel velocity variations to calculate road surface conditions with corresponding braking regulation

Abstract: The vehicle anti-locking braking system regulates the hydraulic brake pressure in response to the detected wheel velocities, to prevent the wheels locking. A cycle period during which the wheel velocity is cyclically varied is detected, with detection of the variation amplitude within each cycle, to evaluate the road surface conditions, using a controller (17) to provide a corresp. brake press regulation during anti-locking braking. ADVANTAGE - Allows braking regulation to be adjusted for different road surfaces.

Dynamic braking circuit in automatically closing door or the like

Abstract: PURPOSE:To obtain the braking characteristic suitable for an automatically closing door or the like by obtaining operational voltage of a control circuit by an output from a generator, in the case of a dynamic braking circuit in which the generator, connected to a rotational sysem, is braked by the control circuit. CONSTITUTION:A dynamic braking circuit, which controls a short-circuit condition of a generator G, connected to a rotational system, by a control circuit to brake the generator G, is provided. In this dynamic braking circuit, operational voltage of the control circuit is obtained by an output from the generator G. In this way, the control circuit is made possible to operate without using a separate power supply, and the braking characteristic, suitable for use in dynamic braking of an automatically closing door or the like, can be realized.

Improvement of transient stability limit using microprocessor controlled dynamic braking system

Abstract: The application of a microprocessor technique can provide an accurate and reliable means for inserting and disconnecting of the DBR (dynamic braking resistor). This technique is based on the realization of the critical clearing time for the particular power system involved. Such a technique can provide the means to assess stability conditions by implementing the method of the rate of change of kinetic energy (RKE). The scheme gives a prototype approach for utilizing an 8-b Intel 8085 microprocessor for the initiation of switching 'in' and 'out' of the DBR. >

Platform escape vehicle

Abstract: A platform escape vehicle, particularly for the rapid escape of derrickman from his monkey-board on a drilling rig, comprises two sheaves (2a, 2b) with twin grooves to take a wire cable (4), mounted on parallel shafts (7) One sheave 2b is provided with a dynamic braking and another sheave 2a is provided with a hand-operated shoe brake The sheaves are connected by parallel supporting straps (6), which are connected to the apex of the body of the vehicle The vehicle comprises two similarly shaped side pieces (11) consisting of upper supports from the shorter ends of which tubular lengths (13) run towards one another and around the bottom of seat (14) and from the longer ends of which pieces tubular lengths (15) run down to practically meet at the mid-point of handle-bars (17) which are provided with levers for hand-operation of the shoe brake from the meeting point of said tubular lengths (15) a downwardly extending tubular length curves outwardly while passing through a hole at the forward end of said seat as far as a lower end (21) having an inverted T shape

Brake system for motor vehicles with electric drive

Abstract: A braking system for electrically driven vehicles consists essentially of a driven front axle (VA) and an undriven rear axle (HA) in the form of a triple-circuit (I, II, III) compound system consisting of hydraulic friction brakes (3, 4, 10, 11) and an electro-regenerative (II) braking system, in which the electro-regenerative braking system makes use of one of the electric drive motors of the motor vehicle for braking and power recovery. The actuation of the friction brakes connected to the second and third braking circuits and the braking force distribution between the front and rear axles are controllable by means of an electronic regulator which receives information via e.g. the brake pedal position and evaluates this information to control the brakes acting on the driven wheels.

Use of the waterways of pump turbines for passage of no-load discharges

Abstract: 1. The existing methods of passing no-load discharges through turbines of low-head hydrostations do not provide reliable operation of the units owing to a considerable increase of the dynamic loads on the runner blades, other elements of the units, and structural members of the station. 2. The proposed method of passing the no-load discharge with the use of dynamic braking according to the given law reduces all dynamic loads with a sufficiently high discharge capacity of the turbine. This is confirmed by full-scale tests of the model. The use of the given method can produce a considerable effect both at existing and newly designed hydrostations. 3. The high values of efficiency and minimum dynamic loads on the pump units operating in the turbine regime allow using the impellers of axial-flow pumps as turbines and motors as generators.

Method and apparatus for controlling braking pressure applied to a vehicle brake

Abstract: A motor speed controller 28 for an anti-lock brake system motor driven brake pressure modulator 18 controls the speed during the pressure ramping phase of an anti-lock brake pressure control cycle by commanding periods of dynamic braking of the motor 30 while the motor current I m is being controlled to ramp the pressure.