WO1991011348A1

WO1991011348A1 - A device in the brake system of motor vehicles and a master brake cylinder unit for use in said device

Info

Publication number: WO1991011348A1
Application number: PCT/DK1991/000024
Authority: WO
Inventors: Niels Oluf Skipper
Original assignee: Tjaereby Elektronik Aps
Current assignee: Tjaereby Elektronik Aps
Priority date: 1990-01-26
Filing date: 1991-01-25
Publication date: 1991-08-08
Anticipated expiration: 1992-07-26
Also published as: AU7218091A

Abstract

In a master brake cylinder (5), whose cylinder chamber (5a) is connected through a pressure chamber (2) and lines (1) with the brake cylinders (not shown) at the individual wheels, a valve slide (3) is inserted between the cylinder chamber (5a) and the pressure chamber (2). The valve slide (3) can be moved between the shown free position in which there is free passage in both directions through a through-opening (3c), and a locked position (not shown) where passage in the direction from the pressure chamber (2) to the cylinder chamber (5a) is blocked by a non-return valve (3a), which thus just permits actuation, but not deactuation of the brakes. Attempts at driving with the valve slide (3) in the locked position (not shown) will therefore cause the brakes to be blocked in the first given brake situation, and further driving is prevented. The valve slide (3) can be moved by suitable remote control means - in the shown example electromagnets (6 and 7) with associated control lines (6a and 7a) - between the said two positions in which the slide is held stably by e.g. a locking ball (10) which engages with one of two locking notches (10a, 10b).

Description

A device in the brake system of motor vehicles and a master brake cylinder unit for use in said device

The invention concerns a device of the type stated in the introductory portion of claim 1.

Devices of this type are used for preventing persons with¬ out authorized access to a vehicle from driving the ve- hicle, and there are already numerous proposals for such devices, cf. e.g. the GB Patent Applications 2 024 351, 2 035 486, 2 195 005 and 2 205 076, the PCT Application 89/01885, the FR Patent Specification 2 541 956 and the US Patent Specifications 3 625 573, 4 546 846, 4 765 362 and 777 377.

In the known devices the non-return valve, which blocks the brake system of the vehicle in the locking situation, is mounted as a more or less free component, which partly makes it vulnerable and relatively easy to bypass by means of a bypass line, partly makes the brake system unneces¬ sarily complicated by requiring special hydraulic connect¬ ing lines.

The object of the invention is to provide a device of the type mentioned in the opening paragraph, which is not vitiated by the above-mentioned drawbacks, and this object is achieved by a device which is characterized according to the invention by the features defined in the character- izing portion of claim 1.

When the non-return valve is mounted in a valve slide, which is in turn journalled in the housing associated with the master cylinder of the brake system, it is consider- ably more difficult than before to disturb the normal blocking function of the non-return valve, and no special hydraulic lines are required since the necessary channels may be arranged in the housing of the master cylinder.

The invention also concerns a master brake cylinder unit for use in a device according to the invention. This unit is of the type stated in the introductory portion of claim 7 and is characterized according to the invention by the structure defined in the characterizing portion of claim 7.

Expedient embodiments of the device and the unit, whose effects will be explained more fully in the following de¬ tailed part of the description, are defined in claims 2-6 and 8-10, respectively.

The invention will be explained more fully below with re¬ ference to the embodiment of the part of a device of the type mentioned in the opening paragraph which is comprised directly by the invention, as shown greatly schematically in the drawing, in which

fig. 1 shows the device with the valve slide in the open position or the free position, while

fig. 2 shows the device with the valve slide in the locked position.

In a vehicle (not shown) in which the device of the inven¬ tion is mounted, the cylinders associated with the indivi- dual brakes are connected through schematically indicated hydraulic lines 1 with a pressure chamber 2, which can be connected by means of a valve slide 3, which is equipped with a non-return valve 3a and is slidingly journalled in a slide chamber 3b, in various ways with the cylinder chamber 5a in a master cylinder 5 defined by a brake piston 4. - 3 -

In addition to the non-return valve 3a the valve slide 3 has a through opening 3c which, in the valve slide posi¬ tion shown in fig. 1, creates unobstructed passage in both directions through the cylinder chamber 5a and the pres- sure chamber 2. In the position shown in fig. 1, the master cylinder 5 will thus operate in normal manner since movement of the piston 4 to the left and to the right in fig. 1 will cause actuation and deactuation, respectively, of the brakes (not shown) connected with the pressure chamber 2.

When the valve slide 3 is in the locked position shown in fig. 2, the connection between the cylinder chamber 5a and the pressure chamber 2 is formed by the non-return valve 3a alone, which just allows flow from the cylinder chamber 5a to the pressure chamber 2, but not vice versa. This entails that movement of the brake piston 4 to the left - i.e. the normal brake movement caused by a brake pedal (not shown) connected in known manner with the piston 4 - will cause brake fluid to flow to the brakes in normal manner, while an oppositely directed movement of the pis¬ ton 4, i.e. to the right, will not cause deactuation of the brakes since the brake fluid, which has now been in¬ troduced into the pressure chamber 2 and from there through the lines 1 into the individual brake cylinders and keep the brakes actuated, cannot flow back to the cylinder chamber 5a since the non-return valve 3a blocks this flow.

If an unauthorized person has nevertheless been able to start the motor of the vehicle and commenced driving, the first situation requiring the brakes to be applied will therefore entail that the brakes are blocked in the ac¬ tuated position, thereby rendering further driving im- possible. The valve slide 3 is adapted to assume both the free posi¬ tion shown in fig. 1 and the locked position shown in fig. 2 in a stable manner, i.e. it requires no external force for securing at one or the other position. Such a "bi- stable" device can be achieved in many different, known manners, including securing in the extreme position by means of permanent magnets, but to facilitate the under¬ standing of the drawing the means necessary for this are symbolized in the form of a spring-loaded locking ball 10, which is adapted to engage with two locking notches 10a and 10b in the valve slide 3 corresponding to the said positions.

The means moving the valve slide 3 between the free posi- tion and the locked position may be of different types, but owing to the fact that the brake cylinders of motor vehicles are usually mounted at a place where a mechanical connection to the dashboard of the vehicle will be incon¬ venient, it is preferred, as shown in fig. 1, to connect the valve slide 3, preferably directly, with a symboli¬ cally shown common armature 3d associated with two, like¬ wise symbolically shown electromagnets 6 and 7, which are adapted to act on the armature 3d in mutually opposite di¬ rections, so that actuation of the electromagnet 6 causes the valve slide 3 to be moved from the locked position shown in fig. 2 to the free position shown in fig. 1, while actuation of the electromagnet 7 correspondingly results in an oppositely directed movement of the valve slide 3, i.e. to the locked position shown in fig. 2.

The electromagnets 6 and 7 are connected through control lines 6a and 7a, respectively, with suitable operating means on or in the vicinity of the dashboard of the ve¬ hicle; these operating means may e.g. be formed by con- tacts on a lockable switch such that turning of this switch to the operating position causes the electromagnet 6 to be actuated, while turning to the rest or locked po¬ sition will cause the electromagnet 7 to be actuated. Pre¬ ferably, the switch is mechanical and/or coupled to the ignition lock of the vehicle such that it cannot be ope- rated when the ignition key is removed.

It being stressed again that the drawing is schematic, it should be mentioned that at least the parts which are mechanically connected with the valve slide 3 and by means of which this could be actuated, are preferably encapsu¬ lated in a manner not shown in the housing associated with the brake cylinder 5. This protects the parts in question against dirt and also reduces the risk of the valve slide being moved to the free position shown in fig. 1 by per- • sons without authorized access to the vehicle.

To additionally reduce the risk of the valve slide being moved to the free position by persons without authorized access to the vehicle, the shown device comprises a pro- tective relay 8 with two operating contacts - i.e. in contacts closed when the relay is switched on - 8a and 8b which are interposed between the electromagnets 6 and 7, respectively, and their control lines 6a and 7a, respec¬ tively. The relay coil 9 of the protective relay 8 is permanently connected to the power supply system of the vehicle through a line 9a, and the relay 8 will therefore normally be kept in- switched-on position so that there is no interruption between the electromagnets 6 and 7 and their control lines 6a and 7a, respectively. If the power supply through the line 9a is interrupted for some reason, the relay 8 is switched off, the operating contacts 8a and 8b are opened, and the electromagnets 6 and 7 can no longer be actuated through the control lines 6a and 7a, respectively. Accordingly, the valve slide 3 cannot be moved and remains in the position last assumed. If the power supply system or the part of it which is connected to the shown device fails during normal driving, where the valve slide 3 is in the free position shown in fig. 1, the valve slide will remain in this position, and the brake system cannot be unintentionally blocked.

If the vehicle stands still and the valve slide 3 is in the locked position shown in fig. 2, cutting of the lines will also cause the valve slide 3 to remain in the posi- tion last assumed, i.e. the locked position, and the valve slide 3 cannot be moved away from this .position, e.g. by short circuit.

The means necessary to move the valve slide 3 are des- cribed in the foregoing as two electromagnets 6 and 7, based on electrical remote control of the valve slide. However, in principle nothing prevents the valve slide 3 from being remote-controlled in another manner, e.g. pneumatically by means of a piston in a cylinder, which requires no detailed explanation since persons skilled in the field will have no difficulty in constructing and creating the necessary pneumatic equipment. It is contem¬ plated that such pneumatic remote control will be used in particular in connection with pneumatically controlled and/or actuated brakes where a compressed air system is already present. Mechanical or hydraulic remote control is also within the scope of the invention, but requires no further explanation for the mentioned reasons.

The relay 8 does not necessarily have to be an electromag¬ netic relay as shown, but may e.g. be formed by a semi¬ conductor circuit with a corresponding function, which persons skilled in the semi-conductor field will be able to construct and create without further instructions. As mentioned before, the brakes are blocked by means of the device of the invention the first time e.g. a person without authorized access to the vehicle actuates the brakes after commenced driving. Then the vehicle remains standing in permanently braked state and may then obstruct the traffic since the vehicle can now no longer be removed without special aids. Furthermore, the brake system may be damaged by being actuated for an extended period of time. Thus, the brakes can e.g. rust in.

In an advantageous embodiment of the invention this draw¬ back can be remedied by the insertion of a time mechanism 11 or timer between the control lines 6a, 7a of the elec¬ tromagnets 6, 7 (fig. 1). This time mechanism 11 includes an electric circuit (not shown) which is so arranged that following a predetermined period of time it first briefly actuates the electromagnet 6 and then changes to actuate the electromagnet 7 briefly. This entails that the pres¬ sure is relieved in the pressure chamber 2, and that the brakes are deactuated thereby so that, if desired, the vehicle can be pulled in so that it does not obstruct the traffic. The period of time which elapses before the time mechanism 11 initiates this process may be selected freely as required, but suitably it may be rather brief, e.g. just a few minutes since the brakes will again be blocked if the said person without authorized access to the ve¬ hicle will try to drive on with the vehicle when the time mechanism 11 had deactuated the brakes.

In another advantageous embodiment a permanently open connection 12 may be provided between the pressure side 5a of the master cylinder 5 and the pressure chamber 2 (fig. 2). This connection 12 has a flow resistance so adjusted that when the valve slide 3 is in its locked position and the brakes are blocked, the pressure in the pressure cham¬ ber 2 is relieved within e.g. the above-mentioned rela- tively short time of some minutes. If it is attempted to drive the vehicle again after this period of time, the brakes are blocked again, and the vehicle cannot therefore be used by persons without authorized access. The last- mentioned embodiment has the advantage that it operates independently of any interruptions of the electrical power supply.

Claims

P a t e n t C l a i m s :

1. A device in the hydraulic or pneumatic brake system of a motor vehicle and of the type comprising a non-return valve (3a) which can be switched between an active posi¬ tion (fig. 2) where it is inserted with normal non-return valve function between the master cylinder (5) of the brake system and the lines (1) leading to the individual wheel brakes and allows flow to it, and an inactive posi¬ tion (fig. 1) where it is not inserted as mentioned, said non-return valve (3a) being mounted in a valve slide (3) which is journalled in sliding and fluid-tight manner in a slide chamber (3b) positioned between the pressure side (5a) of the master cylinder (5) and the pressure chamber

(2) connected with the said brake lines (1), c h a r a c ¬ t e r i z e d in that the valve slide (3) can be moved by means of actuator means (6, 7) seperately actuable in two directions between a first, stable locked position (fig. 2) where just the non-return valve (3a) connects the pres¬ sure side (5a) of the master cylinder (5) with the pres¬ sure chamber (2), and a second and likewise stable free position (fig. 1) in which a through bore (3c) provided in the valve slide (3) connects the pressure side (5a) of the master cylinder (5) with the pressure chamber (2).

2. A device according to claim 1, c h a r a c t e r ¬ i z e in that the two actuator means are electromagnets (6, 7) which are electrically connected to their respec- tive control lines (6a, 7a) through their respective ope¬ rating contacts (8a, 8b) on an electromagnetic relay (8, 9), whose coil (9) is connected (9a) to the power supply system of the vehicle.

3. A device according to claim 1 or 2, c h a r a c ¬ t e r i z e d in that the two electromagnets (6, 7) have a common armature (3d) which is connected with the valve slide (3).

4. A device according to claim 3, c h a r a c t e r - i z e d in that the common armature (3d) is secured to or formed integrally with the valve slide (3).

5. A device according to any of claims 1-4, c h a r a c ¬ t e r i z e d in that a time mechanism (11) is inserted in the power circuit of the electromagnets (6, 7), prefer¬ ably between the control lines (6a, 7a), said time mecha¬ nism being arranged such that when the valve slide (3) is present in its locked position, the time mechanism (11), after a predetermined period of time, briefly actuates first the electromagnet (6) and then the electromagnet (7).

6. A device according to any of claims 1-4, c h a r a c ¬ t e r i z e d in that a permanently open flow connection (12) is provided between the pressure side (5a) of the master cylinder (5) and the pressure chamber (2), said flow connection being formed with such a flow resistance that the pressure in the pressure chamber (2), with ac¬ tuated brakes, is relieved after a predetermined period of time when the valve slide (3) is in its locked position.

7. A master brake cylinder unit for use in a device according to one or more of claims 1-6 and of the type comprising

a) a master cylinder (5) with a piston (4) which is slid- ingly journalled in it and is intended for connection with a brake actuator means, such as a pedal, and

b) a pressure chamber (2) which is connected with the pressure side (5a) of the master cylinder (5) and is intended for connection with brake lines (1) leading to the individual wheel brakes,

c h a r a c t e r i z e d by

c) a slide chamber (3b) which is inserted between the pressure side (5a) of the master cylinder (5) and the pressure chamber (2) and in which a valve slide is journalled in sliding and fluid-tight manner, said valve slide having an opening (3c) which leads from one side to the other and a non-return valve (3a) which leads from one side to the other, said valve slide (3b) being adapted to be moved by seperately actuable actuator means (6, 7) between a first, stable locked position (fig. 2) where just the non-return valve (3a) connects the pressure side of the master cylinder (5) with the pressure chamber (2), and a second and likewise stable free position (fig. 1) in which the opening (3c) connects the pressure side of the master cylinder (5) with the pressure chamber (2)..

8. A unit according to claim 7, c h a r a c t e r i z e d in that the two actuator means (6, 7) are built together with or incorporated in the unit.

9. A unit according to claim 8, c h a r a c t e r i z e d in that the two actuator means are formed by electromag¬ nets (6, 7) with a common armature (3d) which is connected with the valve slide (3).

10. A unit according to claim 9, c h a r a c t e r i z e d in that the common armature (3d) is secured to or formed integrally with the valve slide (3).