Program-controlled car brake gap automatic slack adjuster
Technical field
The present invention relates to brake device for car, particularly relate to a kind of program-controlled car brake gap automatic slack adjuster.
Background technique
The reliability of brake system of car is the key element of vehicle safety travel.The general Pneumatic braking device that comprises air-leg, adjustment arm, break (main element comprises camshaft, cam, brake shoe assembly, brake drum) that uses of current heavy-duty commercial vehicle and motorbus.Owing to need frequent braking in the running process, can make the break heating, brake drum, the expansions such as brake shoe assembly that brake lining is housed can make brake clearance diminish; And long-term use meeting becomes big because of brake pad wear can cause brake clearance.If untimely adjustment, can cause a little stopping, drag stop, phenomenons such as brake drum loses circle, brake drum be full of cracks, cause hidden danger to driving.The adjustment arm then is exactly component assembly of design for ease of manual work adjustment or the brake clearance of adjusting these breaks automatically remain in the reasonable value scope it; Still the straight line motion of air-leg is converted into the rotation of camshaft simultaneously, the transmission of power that is absolutely necessary, switching-over member.The important function of adjustment arm is self-evident.Present adjustment can be divided into hand regulation arm and adjust arm automatically by regulative mode.Hand regulation arm generally includes the brake clearance regulating mechanism of being made up of camshaft power worm gear and the locking of camshaft power worm gear, adjustment worm screw; Automatically adjusting arm then is to increase a self-reacting device on this basis.Also there are many improvements in existing adjustment arm.As, the adjustment of the brake clearance of the braking device of employing hand regulation arm is that the specialty personnel that repair carry out at interval, is not to be in best clearance all the time between the adjustment in twice gap, but changes to the maximal clearance of permission by best clearance; Adopt the adjustment of the brake clearance of the braking device of adjustment arm automatically can remedy this defective of hand regulation arm; But present self-reacting device adopts pure mechanical structure mostly; Structure is comparatively complicated; The deformation of member, Transmitted chains gap etc. are bigger to the reliability effect of regulating, and can only realize unidirectional adjusting, and this also is the one of the main reasons that causes the brake drum be full of cracks or occur phenomenons such as blowing out in the vehicle driving process.
Along with application and the development of sensor technology and electronic auto-control technology at automotive field; As far back as the nineties in last century, patent US4749063 has just proposed a kind of implementation method of automotive brake brake clearance closed loop automatic control system of mechanical, electrical, the gas integral that changes based on real time direct brake monitoring gap value.This method has adopted a kind of gas flow sensor, and its deficiency is that pressurized gas can influence sensitivity and reliability of gas flow sensor etc. to factors such as the receptance of environment, hysteresis qualitys, and the volume ratio of this type sensor is bigger; Be installed on the brake shoe, require existing brake inside structure is done bigger change.Patent CN2849315Y and CN1967007 have also proposed a kind of intelligent high-performance process-controlled fully-automatic automobile braking regulating arm, adopt to be based on the air-leg perception principle.The increment that the wearing and tearing of brake lining will inevitably make the push rod stroke of piston or air chamber produce; The air-leg perception principle is based on the automatic control of this increment, but has ignored the influence to the stroke increment such as excess gap that the brake arm housing produces and elasticity corner, the elasticity corner of brake shoe, the elasticity corner of cam drive axle.
Summary of the invention
The problem that the existing adjustment arm that is equipped with to heavy-duty commercial vehicle and motorbus Pneumatic braking device exists the purpose of this invention is to provide a kind of implementation method of program-controlled car brake gap automatic slack adjuster.Comprise the variable quantity that adopts the angular displacement sensor that is installed in the cam drive shaft end to come the perception brake clearance; Utilize SCM Based electronic controller that the angular displacement signal from angular displacement sensor is handled then; Judge whether that the sending controling instruction drive stepping motor carries out the break brake clearance and regulate, still driving sound, light alarm element carry out the brake troubles warning; The user of service can carry out the setting operation of break prepsetting gap on operation display panel simultaneously, and observes the current service braking gap of break.
The object of the invention can be realized through following technical proposal:
The present invention has the air-leg attachment hole in the upper end of shell, and the camshaft power worm gear that is connected with camshaft of brakes is installed in the lower end of shell, and camshaft power worm gear is adjusted the adjustment that locks on the worm shaft and locked worm screw and be meshed with being installed in.Stretch out at adjustment locking worm shaft on the end of shell the self-regulated worm gear is installed, at the shell side face electronic controller and stepper motor are housed, the self-regulated worm screw that is installed on the live axle of stepper motor is meshed with the self-regulated worm gear; The coaxial end of stretching out that is installed in camshaft of brakes of angular displacement sensor; Locating basis bar one end is fixed in the angular displacement sensor rotating shaft; Stretch out between end face and the locating basis bar in the angular displacement sensor rotating shaft and to be provided with torsion spring, the other end of locating basis bar is connected with frame; Electronic controller is automobile storage battery respectively, sound, light alarm element, and operation display panel, stepper motor is connected with angular displacement sensor.
Said electronic controller comprises single-chip microcomputer, step motor controlled driving circuit, angular displacement signal processing circuit, operation display circuit, alarm element controlling and driving circuit and power supply circuits; Single-chip microcomputer is connected with alarm element controlling and driving circuit with step motor controlled driving circuit, angular displacement signal processing circuit, operation display circuit respectively, and power supply circuits are supplied power to whole system.
Said single-chip microcomputer adopts the AT89C51 chip, its P1 and P2 interface respectively with the angular displacement signal processing circuit in chip AD12XSZ, wherein P2.3, P2.4 and P2.5 respectively with the angular displacement signal processing circuit in BUSY, INH and the EN of chip AD12XSZ be connected; The P2.6 of single-chip microcomputer links to each other with alarm element controlling and driving circuit with P2.7; P0.0~the P0.7 of single-chip microcomputer respectively with step motor controlled driving circuit in chip 74LS373 link to each other with chip 8255A, the ALE pin of single-chip microcomputer links to each other with the G pin of chip 74LS373, the RD of single-chip microcomputer links to each other with WR with the RD of chip 8255A respectively with the WR pin; P1.0~the P1.7 of single-chip microcomputer links to each other with the chip 8279 of operation in the display circuit.
The beneficial effect that the present invention has is:
Can in the vehicle driving process, carry out bidirectional modulation to the break brake clearance automatically, make it always work in best brake clearance state; Can judge whether brake lining needs to change, and malfunction alarm is provided through accumulation regulated quantity (degree of wear); When the brake lining of adjustment arm and better break is installed, can set preset brake clearance through operation display panel, easy to operate; The angular displacement sensor that employing is installed in the cam axle head obtains the brake clearance increment signal; Compare with the system of the gas flow formula brake clearance sensor that is installed in brake inside; Simple in structure, volume is little, easy for installation; More reliable, than adopting automatic adjustment arm to regulate more accurate based on push rod stroke gap perception principle; SCM Based electronic controller controls, control circuit is simple, and cost is lower.
Description of drawings
Fig. 1 is the program-controlled car brake gap automatic slack adjuster general illustration;
Fig. 2 is the mechanical transmission mechanism plan view;
Fig. 3 is the H-H view of Fig. 2;
Fig. 4 is the G-G view of Fig. 1;
Fig. 5 is a program-controlled car brake gap automatic slack adjuster working principle block diagram;
Fig. 6 is the major component block diagram of program-controlled car brake gap automatic slack adjuster electrical principle.
Among the figure: 1, mechanical transmission mechanism, 2, electronic controller, 3, stepper motor, 4, angular displacement sensor, 5, operation display panel, 6, the acoustic alarm element; 7, light alarm element, 8, automobile storage battery, 9, shell, 10, the air-leg attachment hole, 11, capping; 12, camshaft power worm gear, 13, camshaft connects internal spline, 14, adjustment locking worm screw, 15, adjustment locking worm shaft, 16, the self-regulated worm gear; 17, self-regulated worm screw, 18, the live axle of stepper motor, 19, the protection casing, 20, camshaft, 21, the angular displacement sensor rotating shaft; 22, locating basis bar, 23, torsion spring, 24, frame, 25, through hole, 26, manual tune button (forward); 27, manual tune button (reverse), 28, T0 sets button, 29, T1 sets button, 30, numeric display unit, 31, single-chip microcomputer; 32, step motor controlled driving circuit, 33, the angular displacement signal processing circuit, 34, the operation display circuit, 35, alarm element controlling and driving circuit, 36, power supply circuits.
Among the figure: R1-R26 is a resistance, and U1-U3 is a photo coupler, V1-V7, power discharging transistor, and A, B, C, D, E are lead.
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is further described.
Like Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, shown in Figure 6; Mechanical transmission mechanism 1 of the present invention is to have air-leg attachment hole 10 in the upper end of shell 9; The camshaft power worm gear 12 that is connected with camshaft of brakes 20 is installed in lower end at shell 9; The spline 13 that is connected with camshaft of brakes 20 on the camshaft power worm gear 12, camshaft power worm gear 12 is meshed with adjustment locking worm screw 14 on being installed in adjustment locking worm shaft 15.Camshaft power worm gear 12, adjustment locking worm screw 14, the same existing technology of the installation of capping 11 on housing 9.
Stretch out at adjustment locking worm shaft 15 on the end of shell 9 self-regulated worm gear 16 is installed, electronic controller 2 and stepper motor 3 are housed in shell 9 sides, the self-regulated worm screw 17 that is installed on the live axle 18 of stepper motor is meshed with self-regulated worm gear 16.Self-regulated worm screw 17 is installed in the protection casing 19 with self-regulated worm gear 16, and protection casing 19 is fixedly mounted on the side of adjustment locking worm shaft 15 external parts of housing 9.Stepper motor 3 is installed in the side of protection casing 19, and the through hole 25 that the live axle 18 of stepper motor passes on the protection casing 19 is connected with self-regulated worm screw 17.
The angular displacement sensor 4 coaxial ends of stretching out that are installed in camshaft of brakes 20; Locating basis bar 22 1 ends are fixed in the angular displacement sensor rotating shaft 21; Stretch out between end face and the locating basis bar 22 in angular displacement sensor rotating shaft 21 and to be provided with torsion spring 23, the other end of locating basis bar 22 is connected with frame 24; Wherein torsion spring 23 1 ends are fixed on the baseline rod 22, and the other end is fixed on the shell of angular displacement sensor 4.
Electronic controller 2 is installed in the position of shell 9 or guard box 19 outsides or other easy operating; It is automobile storage battery 8 respectively; Sound, light alarm element 6,7, operation display panel 5 adopts lead A, lead B, lead C, lead D to be connected with lead E between stepper motor 3 and the angular displacement sensor 4.
Said electronic controller 2 comprises single-chip microcomputer 31, step motor controlled driving circuit 32, angular displacement signal processing circuit 33, operation display circuit 34, alarm element controlling and driving circuit 35 and power supply circuits 36; Single-chip microcomputer 31 is connected with alarm element controlling and driving circuit 35 with step motor controlled driving circuit 32, angular displacement signal processing circuit 33, operation display circuit 34 respectively, 35 pairs of whole system power supplies of power supply circuits.
Described acoustic alarm element 6 is installed in the easy observed position of operator cabin with light alarm element 7, adopts lead B to connect between they and the electronic controller 2.
Said operation display panel 5 is installed in the position of shell 9 or guard box 19 outsides or other easy operating, comprises manual tune button 26 (forward), 27 (reverse), and T0 sets button 28, T1 sets button 29, and numeric display unit 30.
Said single-chip microcomputer 31 adopts the AT89C51 chip, and step motor controlled driving circuit 32 has adopted A/D conversion chip 74LS373 chip and programmable interface chip 8255A and comprised the big loop of photoelectricity isolation power amplifier that photo coupler (U1-U3) transistor (V1-V6) is formed; Operation display circuit 34 has adopted universal keyboard/display interface chip 8279 and chip 7407 and 7406, comprises that numeric display unit 30 adopts 4 cloudy LED altogether; Angular displacement sensor 4 adopts XZ series rotary transformer; Angular displacement signal processing circuit 33 has adopted XSZ series conversion module; Stepper motor 3 has adopted three-phase stepper motor.The P1 of AT89C51 chip and P2 interface respectively with angular displacement signal processing circuit 33 in chip AD12XSZ, wherein P2.3, P2.4 and P2.5 respectively with angular displacement signal processing circuit 33 in BUSY, INH and the EN of chip AD12XSZ be connected; The P2.6 of single-chip microcomputer 31 links to each other with alarm element controlling and driving circuit 35 with P2.7; P0.0~the P0.7 of single-chip microcomputer 31 respectively with step motor controlled driving circuit 32 in chip 74LS373 link to each other with chip 8255A; The ALE pin of single-chip microcomputer 31 links to each other with the G pin of chip 74LS373, and the RD of single-chip microcomputer 31 links to each other with WR with the RD of chip 8255A respectively with the WR pin; P1.0~the P1.7 of single-chip microcomputer 31 links to each other with the chip 8279 of operation in the display circuit 34.
Working procedure of the present invention:
The user when program-controlled car brake gap automatic slack adjuster is installed, or when changing the break brake lining, can be through the easy to operate adjustment arm of operation display panel 5 being installed and being realized to the adjusting of the brake clearance of regulating brake and preset.Detailed process: operation manual tune button 26 (forwards) and 27 (reverse); Can receive the state signal of manual tune button 26 (forward) and 27 (reverse) based on the operation display circuit 34 of universal keyboard/display chip 8279; After the A/D conversion, signal conveys is arrived single-chip microcomputer (AT89C51); Single-chip microcomputer (AT89C51) judges whether to send control command drive stepping motor controlling and driving circuit 32; Comprise pulse signal, direction signal and off line signal etc., make stepper motor 3 work, step motor drive axle 18 drives self-regulated worm screw 17 rotation synchronously; Self-regulated worm screw 17 makes engagement driving with self-regulated worm gear 16; Drive adjustment locking worm screw 14 through adjustment locking worm shaft 15 and rotate synchronously, adjustment locking worm screw 14 makes engagement driving with camshaft power worm gear 12, impels camshaft power worm gear 12 to turn an angle with respect to shell 9 and reaches the purpose of adjusting; Process is transferred to operation display circuit 32 behind single-chip microcomputer (AT89C51) the logical process conciliation amount signal therewith, after its conversion, shows at numeric display unit 30.When definite break brake clearance has met prepsetting gap; Be in off working state at brake system of car, set button 28 by a T0, in running order at brake system of car; Set button 29 by a T1; Can accomplish the setting operation of break prepsetting gap, single-chip microcomputer (AT89C51) can be stored in the corresponding embedded memory, in vehicle traveling process, the break brake clearance being adjusted use automatically.Wherein, Preset brake clearance is that the difference through angle T1 and angle T0 reflects; T0 is the angle (initial angle) of adjustment arm housing 1 and locating basis bar 22, and T1 is that break is operated in angle and the initial angle sum that prepsetting gap state lower casing 9 should turn over, and claims the prepsetting gap angle again.
In vehicle traveling process, braking process is defined as a kind of brake petal of stepping on the braking main valve from the driver to the process that is totally released brake petal.In braking process, shell 9 actual maximum angles that turn over (consistent with the camshaft rotation angle) and initial angle sum are referred to as the actual gap angle here, represent with t.
In vehicle traveling process; Each braking process angular displacement signal processing circuit (AD12XSZ) 33 all will receive the signal of the actual gap angle t that monitors from angular displacement sensor 4; After angular displacement signal processing circuit (AD12XSZ) 33 conversions, transport to single-chip microcomputer (AT89C51) through P1 mouth and P2 oral instructions; Single-chip microcomputer (AT89C51) judges whether to send control command; The T0 of correspondence and the setting value of T1 in the updated stored device, drive stepping motor controlling and driving circuit 32 starts the brake clearance adjustment processes, or driving alarm element drive circuit 35 carries out malfunction alarm.Concrete steps:
1. single-chip microcomputer takes out T1 and t compares from corresponding embedded memory; And sending controling instruction driving operations display circuit 34 work; Numeral shows actual gap amount (being obtained through the logic program computing by t and T1); And judge | whether t-T1| is more than or equal to minimum controlled variable a (a is confirmed by the step angle of stepper motor), if get into step 2; Otherwise, get into step 5.
2. whether judge S=S+ (t-T1) less than Smax, if, get into step 3, otherwise control command takes place to alarm element drive circuit 35, drive acoustic alarm element 6 and 7 work of light alarm element.
S regulates the cumulative angle value for all previous brake clearance in the storage embedded memory, has reflected break brake lining wear extent; Smax is solidificated in the extreme angles value that the current brake clearance deposited with the constant form in logic program or the corresponding stored device can be regulated, and is relevant with the tear-to-wear allowance of break brake lining.
3. single-chip microcomputer (AT89C51) sends the controlling and driving instruction to step motor controlled driving circuit 32, makes its work.Utilize N=|t-T1|/a, N rounds, and confirms to send number of pulses; If be positive number (t-T1), send the postive direction signal, otherwise send the negative direction signal; The angle value signal that these process angular displacement sensor 4 feedback monitorings arrive, when the angle that reaches correspondence is T0+ (t-T1), single-chip microcomputer (AT89C51) will send the off line signal to step motor controlled driving circuit 32, and step motor controlled driving circuit 32 quits work.
4. single-chip microcomputer (AT89C51) upgrades the heavy variable of corresponding memory.The value of upgrading S is S+ (t-T1), and the value of T0 is T0+ (t-T1), and the value of T1 is T1+ (t-T1).
5. the one action circulation is accomplished.