CN1257078C - Pneumatic braking booster with improved braking law - Google Patents

Abstract

In order to avoid that a sudden release of the brake pedal on the driver's part should result in an impact, the invention provides that a sudden release, which follows a sudden application on the brake pedal, is followed by automatic braking maintenance, for a certain time interval. This is obtained by mounting in a moving element of a pneumatic brake booster a circuit with mechanical hysteresis. A displacement of the load transmission components in said circuit is different depending on whether the force is normal or sudden. If it is sudden, a plunger comprising a distributor (18) and a probe (15) is carried against a reaction disc (29). If said sudden force is followed by sudden release, the probe remains active via a ratchet handle (32, 33, 34) while the distributor moves backwards.

Description

Has the air-operated brake servo unit that improves braking principle

Technical field

The purpose of this invention is to provide a kind of air-operated brake servo unit that improves braking principle that has that is used for emergency braking.The objective of the invention is in the chaufeur braking, prevent the maloperation of chaufeur.More generally, the present invention is intended to the power-assist power that provides bigger under the emergency braking situation.

Background technology

In general, air-operated brake servo unit comprises a variable displacement front chamber, and described front chamber is separated by the rear chamber that a dividing plate and is similarly variable displacement, and described dividing plate is made of a sealed soft diaphragm and a rigid skirt.Rigid skirt drives a pneumatic piston, and described pneumatic piston rests on by a push rod in the main piston of a master cylinder of hydraulic brake circuit, and master cylinder is tandem main cylinder preferably.The front chamber that is arranged on master cylinder one side pneumatically is connected on the vacuum source.Rear chamber relative with front chamber and that be arranged on brake pedal one side controls by valve, pneumatically is connected to propelling fluid source-the be preferably air under bar pressure.Under static state, that is to say when chaufeur does not have push down on the pedal that it is communicated with front chamber and rear chamber each other, and rear chamber and bar pressure are isolated.In braking, front chamber at first separates with rear chamber, then in the air admission rear chamber.Entering of air can promote dividing plate, and aerobraking power-assist power is provided.

At braking procedure--the problem that particularly occurs in the emergency braking is relevant with the maloperation of chaufeur.In the time of the chaufeur emergency braking, his brake pedal that tramps with one's feet down suddenly.Find that through observing statistics it is panic that chaufeur is easy to the emergentness of the braking that causes because of its behavior, can worry by the light of nature to break away especially, can be observed: chaufeur can unclamp pin and trample power on pedal, even have only part second.Then, it is serious that his brain is analyzed situation, thereby confirm the trampling order, so chaufeur jams on down pedal this moment decidedly, perhaps during whole braking, keeps hem facing by application of force state, therefore increased stopping distance.Wherein, self-propelled vehicle is not braked in second that part, and this causes the self-propelled vehicle clobber usually.In other situation, emergency braking can make driver fatigue because the application of force is fierce, and this itself can cause loosening the power that is applied on the brake pedal again.Chaufeur calmness subsequently gets off, and applies a subsidiary load once more and presses pedal again.Obviously during this section, self-propelled vehicle is not braked.In other situation, chaufeur need to be determined all can hesitate before the real braking behind emergency braking.

In all these situations, by statistics, level period second that does not have braking of several centiseconds to a second is the major cause that has an accident.

Summary of the invention

The present invention attempts to solve this problem by giving a kind of intelligence of brake circuit, so that avoid this phenomenon or reduce this phenomenon at least and then the generation of minimizing accident.Which principle of the present invention is to discern on the one hand is the braking that needs this intelligence to intervene, and which is the braking that only need consider the chaufeur action.In the present invention, the unexpected degree of braking is depended in this selection.Can see that the speed by the action that chaufeur applied can differentiate first kind of situation and second kind of situation.Second principle of the present invention is that in the time of the needs intelligent brake, described braking can be kept, and described braking keep need not to use with chaufeur in pushes pedals time first time big power equally of exerting oneself.In other words, described braking keep with after unclamp generation.After unclamp after the pin of chaufeur unclamps.Therefore just there is one to unclamp delay.Therefore when trampling for the second time, braking is not totally released, the merit that chaufeur will be done thereby smaller, and brake operating is quicker.

There are two kinds of ways can reach this purpose.Perhaps use an electron steering, it acts on the hydraulic brake master as an auxiliary brake boost job, perhaps uses air assisted itself, gets involved at first under the described air assisted normal circumstances.In this case, preferably implement a simple mechanism so that reach described result.The advantage of this simple mechanism is before its operation of wear-out failure, to have permanent service life.

Or rather, in described situation, the mechanism that is proposed has a card and ends the type device in brake-force transmission mechanism, preferably in by auxiliary brake-force transmission mechanism, and its stopper is just startup under the unexpected situation at braking force only.This emergentness is because the inertia difference of booster brake different piece causes.In one embodiment, directly ordered about inertia that a control stalk of motion has inertia less than pneumatic piston by the pin of chaufeur.Thereby cause between described control stalk and the described pneumatic piston and to exist one to relatively move.When these two members remain static, described clamping device is originally on the primary importance that limits between described two members, when they are subjected to unexpected braking force effect, described clamping device thereby be bonded between described two members, so that they are remained on the position that it arrived discretely.Described maintained separation is used to keep braking then.But keeping of described braking is temporary transient.If pin is depressed again immediately, just temporarily keeping of described braking can play a role once more.If opposite, pin has really left pedal, and the dividing plate between two chambers returns to original position naturally.When returning to the home position, the mobile of one of these members is used to make clamping device to throw off.

Therefore, the objective of the invention is to propose an air-operated brake servo unit, it comprises:

One can with vacuum source bonded assembly front chamber,

One can with high pressure entry bonded assembly rear chamber,

One removable seal diaphragm between two chambers,

One air assisted piston,

One brake rod,

One hydraulic brake master,

One plunger, described plunger drive by brake rod and with the hydraulic brake master mutual action,

One allows high-pressure fluid enter the device of rear chamber in braking,

-described plunger comprises one and the direct acting tactility apparatus of hydraulic brake master and a distributing box, and described tactility apparatus is relative movable with described distributing box,

It is characterized in that:

-described tactility apparatus on the one outer wall, comprise a hole and

One clamping device is arranged between the inwall of the outer wall of described tactility apparatus and described pneumatic piston, near place, described hole.

Description of drawings

Read following description with reference to accompanying drawing, the present invention may be better understood.Described accompanying drawing is only as indicating and non-exclusively being illustrated what inventing, wherein:

Fig. 1 is the global sections figure of air-operated brake servo unit of the present invention;

Fig. 2 and 3 uses under (emergency braking) situation the scheme drawing of piston mode of the present invention according to air-operated brake servo unit in (slow application) under static or the normal use situation or quick.

The specific embodiment

Fig. 1 illustrates the air-operated brake servo unit that improves braking principle that has that is used for emergency braking according to of the present invention.This air-operated brake servo unit comprises a front chamber 1, and described front chamber can be connected with a vacuum pump (not shown) by an interface tube 2.Vacuum pump is made of the petrolic intake interface of self-propelled vehicle usually.If self-propelled vehicle uses diesel motor, just should use an external vacuum pump.Air-operated brake servo unit also comprises a rear chamber 3, and it can be connected with high pressure entry 5 by for example valve 4, and described high pressure entry is generally the air intake that is under the bar pressure.Air-operated brake servo unit also comprises a moveable bulkhead 6, and described dividing plate is equipped with a rigid skirt and a seal membrane usually.Diaphragm has cut off the pneumatic connection between two chambers.Dividing plate 6 has a seal bore 7, is used to allow movable fixture 8 pass through.Device 8 is mechanically connected on the brake pedal by a brake control rod 9 on the one hand, is connected on the other hand on the hydraulic brake master 10.The power-assisted principle of described air-operated brake servo unit is as follows.Under the effect of control stalk 9, movable fixture 8 enters in the rear chamber, opens valve 4 simultaneously, makes ambient air to enter rear chamber 3 by this valve.Ambient air applies a pressure on dividing plate 6 then, is aided with the action of the bearing 11 that links to each other with control stalk 9, and described dividing plate 6 drives movable fixture 8, makes that the latter's a end 12 can start hydraulic brake master 10.

In this mechanical solution, feature of the present invention mainly is the structure of movable fixture.At first, will introduce a preferred implementation of this movable fixture, how will illustrate then derives a plurality of enforcement modification from it.The part of represented hydraulic brake master 10 illustrates the master cylinder 13 and the cylindrical line pressure chamber 14 that have known valve member.Fluid under pressure in chamber 14 is assigned on the brake equipment by master brake cylinder 10 unshowned remainders.

What Fig. 2 and 3 represented is the plunger of movable fixture 8 and particularly this movable fixture.Plunger comprises the cylindrical tactility apparatus 15 of a hollow.Therefore this tactility apparatus 15 comprises a circle wall 16 that exceeds above base 17.The distributing box 18 of a gyro-rotor formula has a protrusion 19, this protrusion be sliding engaged to by the circle wall 16 formed emptying apertures of tactility apparatus 15.At an end relative with protrusion 19, distributing box 18 has one by circle wall 21 formed emptying apertures 20.Be furnished with a flange 22 on the circle wall 21, this flange is used for touching by last valve 23.Valve 23 can be realized air assisted according to clamped the putting of the pressure of control stalk 9.For this reason, if control stalk 9 is the directional controls along movable fixture 8, the flange 22 of distributing box 18 keeps away the contact part with valve 23.Under such condition, can enter first distribution cavity 25 from servo-unit 24 inlet airs that enter the mouth, described first distribution cavity is between the outer bulkhead 26 of the circle wall 21 of distributing box 18 and servo-unit.By first distribution cavity 25, air can enter rear chamber 3.When entering rear chamber, be in the air push moveable bulkhead 6 under the bar pressure, described dividing plate drives pneumatic piston 27 and moves to hydraulic brake master.Pneumatic piston 27 links to each other with steady ring 28, and described steady ring is round the base 17 of tactility apparatus 15.Steady ring 28 and base 17 have also occupied the entire upper surface of reaction plate 29 (for example being made by rubber), and described reaction plate leans against on the head 30 of push rod 31 at another side.

If not emergency braking, described different position component still keep constant relatively.In fact, thereby brake rod 9 presses against on the distributing box 18---and promote tactility apparatus 15, can make the base 17 of this tactility apparatus 15 trend towards entering in the dish 29.But the purpose of described pushing also is to open valve 23, so that allow air admission, makes on the dish 29 around steady ring 28 toward base 17.In this case, the whole assembly that comprises control stalk 9, distributing box 18, tactility apparatus 15, pneumatic piston 27, dish 29 and push rod 31 can move as sample as the same integral rigidity member.

However, be understandable that the inertia between control stalk 9, distributing box 18, tactility apparatus 15, reaction plate 29, pneumatic piston 27 and the steady ring 28 is different.Therefore according to the present invention, only under the situation of slow application or common braking, perhaps under the situation of any non-emergent braking, aforesaid assembly is deformed, thereby it is worked as same integral rigidity parts.

What Fig. 3 represented is what happens when a unexpected power is applied on the control stalk 9.At this moment, the air of base 17 in entering chamber 3 of tactility apparatus 15 can begin before the start pneumatic piston 27, begins to press to be trapped in to coil 29 li.Therefore, steady ring 28 relative tactility apparatus 15 raise.Correspondingly, circle wall 16 is sagged with respect to piston 27.In other words, from Fig. 2 to Fig. 3, the relative piston 27 in the position of circle wall 16 changes.Thereby can utilize the described relative change of movable fixture different component, be used for making a clamping device to engage.

In a preferred embodiment, this clamping device is formed by the hole 32 (Fig. 2) that is arranged on the circle wall 16 on the one hand.On the other hand, this clamping device comprises a ball 33 herein, preferred one group of a plurality of ball, especially one group of three ball, and described three balls are around circle wall 16 120 ° of arrangements at interval.In addition, this clamping device is formed by a dip plane 34 of pneumatic piston 27.Leave a hole or one group of a plurality of hole even be preferably to simplify in circle wall 16 and make and leave a groove--not difficult.It is not difficult to make ball 33 yet.Preferably by adding an intermediate member 35, so that make an internal conical surface 27 li of pneumatic pistons, this intermediate member 35 is the bell body of a taper on the whole, and has vertical and be stepwise out-of-position flank 36, and an open top 37.Described bell body 35 also passes through seal ring 38 close-fittings in pneumatic piston 27 inside, thereby avoids pneumatic leakage.The top of bell body 35 is positioned at control stalk 9 those sides, and the base of bell body 35 is positioned at bar 31 those sides.The top of bell body 35 has a tapered portion near opening 37 places, and forms the dip plane 34 of rotating bearing ball 33 thus.

Ball 33 is too big, and can't be by 37 li of openings remaining and be positioned at the space at the periphery place at circle wall 16 tops.And ball 33 also is pressed towards circular conical surface 34 and circle wall 16 by a sleeve 39 that has through hole 40.Through hole 40 is circular, and is bigger slightly than the diameter of ball 33, perhaps is bonded on the slightly larger in diameter of the part in the described through hole than ball.The flange 41 that sleeve 39 and is positioned at described sleeve 39 tops links to each other.Spring 42 lean against on the one hand flange 41 below, and lean against on the other hand on the piston 27, particularly lean against on the bell body 35.Spring 42 is compressed, thereby and promotes the tapered opening 37 that flange 41 through holes 40 pull to ball 33 bell body 35 towards the direction of control stalk 9.But because described opening is too narrow, ball can not come off away from opening.But, the antagonistic force of the conical suface 34 of the power of through hole 40 and bell body 35 is pushed ball 33 to circle wall 16.It is also to be noted that ball 33 thereby lose axial freedom with respect to piston 27.Therefore in the emergency braking process, tactility apparatus 15 brings to ball 33 on the opposite of emptying aperture 32 (preferably groove 32) with respect to piston 27, promptly with respect to the relatively moving of surface 34.When emptying aperture 32 during over against ball 33, spring 42, through hole 40 and conical suface 34 thereby promote ball it is bonded in the emptying aperture 32 (perhaps corresponding grooves).

Will this thing happens when chaufeur is trampled brake pedal fast.Two kinds of schemes are introduced in the back.Perhaps chaufeur remains on its pin on the pedal, and perhaps he takes away pin suddenly-a kind of situation that needs prevention.Under first kind of situation (and not corresponding to Fig. 3), valve 23 still separates with flange 22, makes piston 27 can begin to provide a braking power-assist power.At this moment, the part of the antagonistic force that produces and transmit by reaction plate 29 from hydraulic brake master 10 is obtained by pneumatic piston, in fact can alleviate the power that chaufeur need provide.What Fig. 3 represented is behind described emergency braking, situation about taking place when the effect of pin on brake pedal moves suddenly wholly or in part.At this moment, distributing box moves backward because it inevitably Be Controlled bar 9---described distributing box is fixed on the described control stalk---drive and retreat.In this case, flange 22 promotes valve 23, thereby described valve can be so that first distribution cavity 25 and second distribution cavity 43 be communicated with.This second distribution cavity 43 is communicated with front chamber 1.This makes and the vacuum of rear chamber 3 by existing in the front chamber 1 that is communicated with it reaches vacuum state again.

But, in the process of motion backward, be held by the braking force of control stalk 9 normal delivery inclined-plane 34 by groove 32, ball 33 and bell body 35.In this case, the base 17 of plunger 15 continues applying the power that should end under the normal circumstances on the bar 31.Thereby can see that protrusion 19 slides into and is arranged in circle wall 16 in-to-in holes, though plunger 18 should be separated from from described hole.

Therefore at the beginning, protrusion 19 just leans against on the base 17, because the power that acts on the brake pedal is dropped back, described protrusion 19 moves backward then.Then, make rear chamber 3 be in vacuum state and try hard to recommend the little by little motion backward of moving piston 27 by what retracing spring 44 applied.But this gradually after withdraw the membership and keep temporary transient (and slowing down) braking, if chaufeur is trampled brake pedal once more, just can utilize described temporary transient braking mode once more.

If fully continue braking behind the emergency braking, pneumatic piston 27 makes flange 41 touch by a last spanner body (cl é) 45 towards the upward movement of control stalk 9 so, and described spanner body retaining leans on or is connected in mutually on the outer bulkhead 26 of brake servo unit.Therefore, spanner body 45 as the same support that is equipped with an opening 46, the main body of plunger 18 is then passed from the opening of described support.For this reason, the main body of plunger 18 has another flange 41 in protrusion 19 those sides, maintains distributing box 18 thereby spanner body 45 also is used for floating ground.Spanner body 45 itself also can float.Just most critical is, at going-back position, the spanner body leans against on the dividing plate 26 on the one hand, and clamping device is opened in release on the other hand.

When flange 41 touched by upper ejector lever body 45, spring 42 was compressed, and through hole 40 moves down with respect to piston 27, thereby forced ball 33 to leave groove 32, so that brake servo unit is returned to the position that Fig. 2 represents.When emergency braking was accompanied by lasting braking, all brakings have all carried out and clamping device is lockable.In the time of above-mentioned end of braking, just release of clamping device.

It is a preferred implementation as 33 form that clamping device is embodied as ball.But,, can adopt another card to end the mating system of type owing between the end of control stalk 9 and 15 two parts of tactility apparatus, relatively move.For example, the opening 37 of circle wall 16 and bell body 35 can all be furnished with a flexible rack, and it allows bell relatively body 35 interlockings of tactility apparatus 15.In this case, spanner body 45 should have the separately effect of the tooth of these tooth bars, unless use is disposable use type.

The advantage that has the system of ball is very reliable, and can bear sizable power, and the member of forming described system is deformed.From this point, design point of the present invention is, when protrusion 19 retreated, the length of protrusion 19 made protrusion 19 continue to apply an antagonistic force in circle wall 16, was applied to pressure on the circle wall 16 so that overcome ball 33 when separating between retaining member.

The shape of groove 32 and dip plane 34 will be fit to the diameter of ball 33.Especially described surface is an introversion, and (c  nes d ' absorbance), these receive circular cone to have specification with ball 33 contacted surfaces so that have the circular cone of receiving.

Except a protrusion being arranged on the distributing box and having on the tactility apparatus the circle wall, also can be conversely, circle wall on the distributing box and protrusion on tactility apparatus.At this moment, ball 33 is supported on the pedestal of protrusion of tactility apparatus.

Therefore, plunger comprises two members, i.e. distributing box 18 and tactility apparatus 15.Having only one in the described member is tactility apparatus 15, always directly acts in the hydraulic brake master by reaction plate 29.Distributing box 18 is only when normally or suddenly jamming on down pedal or pedal and slowly retreating, just and the hydraulic brake master mutual action.On the contrary, when retreating suddenly (Fig. 3), distributing box no longer directly acts on hydraulic brake master.

Claims (10)

1. air-operated brake servo unit, it comprises:

One can with vacuum source (2) bonded assembly front chamber (1),

One can with high pressure entry bonded assembly rear chamber (3),

One between two chambers removable seal diaphragm (6),

One air assisted piston (27),

One brake rod (9),

One hydraulic brake master (10),

One plunger (15,18), its drive by described brake rod and, with the hydraulic brake master mutual action,

One allows high-pressure fluid enter the device (23) of rear chamber in braking,

-described plunger comprise one with the direct acting tactility apparatus of hydraulic brake master (15) and a distributing box (18), described tactility apparatus and described distributing box are relative activities,

It is characterized in that:

Described tactility apparatus on an outer wall (16), comprise a hole (32) and

One clamping device (33,34) is arranged between the inwall of the outer wall of described tactility apparatus and described pneumatic piston, near place, described hole.

2. servo-unit as claimed in claim 1 is characterized in that, described hole is a form of grooves.

3. servo-unit as claimed in claim 1 is characterized in that, the inwall of described pneumatic piston is taper (35,34).

4. servo-unit as claimed in claim 1 is characterized in that described tactility apparatus and distributing box slide mutually.

5. servo-unit as claimed in claim 1 is characterized in that described distributing box slides in described tactility apparatus.

6. servo-unit as claimed in claim 1 is characterized in that, described clamping device comprises one group of ball.

7. servo-unit as claimed in claim 6, it is characterized in that, described ball is maintained by a sleeve (39), and described sleeve is furnished with a through hole (40) and a flange (41) and a spring (42), and described spring is resisted against on described pneumatic piston and the described flange.

8. servo-unit as claimed in claim 7 is characterized in that, described servo-unit comprises a spanner body (45) that leans against on the described flange.

9. servo-unit as claimed in claim 8 is characterized in that, described spanner body floats.

10. as each described servo-unit in the claim 1 to 9, it is characterized in that described tactility apparatus directly acts on by a reaction plate (29) and described hydraulic brake master.