DE2529595A1 - ACTUATING DEVICE FOR A PRESSURE DIFFERENCE WARNING DEVICE - Google Patents

Description

Actuating device for a pressure difference warning device

The invention relates to an actuator for a pressure difference warning device that detects when a The pressure difference between the brake circuits of a hydraulic dual-circuit brake system exceeds a predetermined value, can be acted upon by a pressure which is arranged in a housing and is supplied to the brake circuits at opposite ends Unit and a display device that can be actuated by the unit when the pressure difference to which the unit is exposed exceeds the predetermined value, and is automatically rendered ineffective if the pressure difference is reduced to an amount smaller than the predetermined value.

In a known embodiment of an actuating device for a pressure difference warning device, this has Unit has a pair of sleeves working in a bore in the housing and a piston that is in alignment with one another axially aligned holes in the sleeves works. If the pressure difference is less than the predetermined value, they are Sleeves prevented by stops from approaching each other

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to move, and the unit is held in a central position. The engagement relationships between the sleeves and the piston are designed so that axial adjustment of the piston relative to the sleeves in from the stops or the Stop device is prevented from leading directions so that one of the sleeves with the piston opposite the other sleeve can be adjusted as soon as the pressure difference exceeds the predetermined value, whereby the display device is operated. After the pressure difference has been reduced to an amount less than the predetermined value, and when the force exerted by the end of the assembly formed by the piston and by said one sleeve acting pressure is applied to the unit is greater than the force applied at the opposite end, which is only is effective over the surface of the piston, the unit is returned to said central position and the Display device is rendered ineffective.

The invention relates to an actuating device of the type described at the outset, in which, according to the invention, the Unit a working piston in a bore in the housing and a pair of axially spaced apart has flexible diaphragms which act on opposite ends of the piston, at their remote from the piston End faces can be acted upon by the pressure prevailing in the brake circuits and have effective surfaces which are larger than that of the piston, but normally when the unit is in a central position of rest and the Pressure difference is smaller than the predetermined value, with, based on the piston, radially outward areas abut walls of the housing located at opposite ends of the bore so that the effective surfaces of the ends of the unit are equal to the effective areas of the piston, whereby, if the pressure difference exceeds the predetermined value, the piston is moved by one of the diaphragms in relation to the bore and the display device is activated, this membrane penetrates into the associated end of the bore and

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the other membrane is urged away from the wall at the opposite end of the bore so that they are effective over their whole Area is acted upon by pressure, and after dropping the pressure difference to an amount smaller than that predetermined value is the force exerted by the pressure acting on the full effective area of said other membrane is exercised on the unit, the unit returns to the central rest position and the display device is switched off will.

The piston can act directly on the display device. However, the piston preferably acts via a lever mechanism on the display device to determine the actual movements required to operate the display device of the membranes to decrease.

According to an advantageous feature of the invention, the lever mechanism has a lever which at one end to a Kippauflager is pivotable in the housing and at a point located between its ends with a Kippauflagerring pivotally and slidably engages the piston, as well as an elastic device on the opposite end of the lever acts and creates a frictional force that holds the piston in the position it occupies when the pressure difference exceeds the predetermined value. In this way the elastic device does not act on the piston a radial direction, whereby displacement of the piston in the bore could be hindered.

The invention is described below with reference to schematic drawings several embodiments explained with further details. In the drawing shows:

Pig. 1 shows a longitudinal section through an actuating device for a pressure difference warning device for a hydraulic dual-circuit brake system,

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Pig. 2 shows a section along line 2-2 in Pig. 1 and

3 and 4 each show a longitudinal section through an actuating device for a pressure difference warning device, each in a different form.

The actuating device shown in the drawing for a pressure difference warning device has a housing 1 on, in which a longitudinal bore 2 is formed. This has chambers 3 and 4 forming chambers at opposite ends Bore widenings that are closed with plugs 5 and 6.

A unit which is arranged in the housing 1 and responds to pressure includes a piston 7 which works in the bore 2 and has substantially the same length as this, and a pair of axially spaced apart Diaphragms 8 and 9 'which are larger in diameter than the piston 7 and act on its opposite ends. To the Outer peripheral edges of the membranes 8 and 9 located beads or thickenings 10 are at the interfaces between the Borehole extensions and a shoulder or wall 11 resp. at the diameter transitions between the bore 2 and the bore enlargements through the inner end of the plug 5 and 6 forwardly projecting, hollow extensions 13 and 14 provided with openings are pressed on. The inside diameter both extensions 13 and 14 are larger than the diameter of the piston 7> so that in the drawn central position of the piston 7 having radial spacing annular Areas of the membranes 8 and 9 on the shoulders or walls 11 and 12 are held in contact. The effective areas of the diaphragms 8 and 9 are therefore equal to the opposite ends of the piston 7

The housing 1 has a radial blind bore 15 which intersects the bore 2 in the longitudinal direction in the middle. in the Piston 7 is a diametrical center in the longitudinal direction

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Bore 16 formed, the. is smaller in diameter than the bore 15. To a lever mechanism arranged in the housing 1 includes a lever 17 'which is engaged by an elastic device 19 at its inner end a tilting support 18 is pushed by the closed inner end of the blind hole 15 is formed. The elastic Device 19 »in the example shown, a compression spring, acts on the lever 17 via a hollow piston 20, which is in a Bore extension 21 is slidably guided. At a point located between its ends, the lever 17 a tilting support ring 22 of circular cross-section, which can be rolled and displaced on the walls of the bore 16 is.

A display device with an electrical switch 23 penetrates the housing through a transversely directed bore 24 one, which has a contact piece 25, which is located with the lever 17 at the lowest point facing away from the tilting support 18 free end is engageable.

The chambers 3 and 4 are connected to separate hydraulic brake circuits via radial connections 26 and 27 in pairs Dual-circuit braking system can be connected.

The difference between the pressures applied to opposite ends of the aggregate is less than a predetermined one Value, the unit remains as a result of the spring-loaded piston 20 acting on the lever 17. generated frictional force in the drawn central position. In this position, the lever 17 engages the contact piece 25, so that the display device is held in a rest position.

If the pressure difference exceeds the predetermined value, For example, if the brake circuit connected to the connections 26 fails or malfunctions, the pressure in the chamber falls from and the pressure in the chamber 4, which is on the with the surface

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of the piston 7 acts the same area of the membrane 9, the urges Aggregate to the left. As a result, the membrane 9 is deformed in such a way that it penetrates into the bore 2, while the membrane 8 is stretched and moved away from the wall or shoulder 11. By adjusting the piston 7, the lever 17 is moved by the Tilt support 18 pivoted, the free end being displaced relative to the piston 20, the engagement position with the contact piece 25 leaves and in the in Fig. 2 with dashed lines Working position drawn in lines goes. This actuates the display device. After the pressure difference has been eliminated the lever 17 is in the working position mentioned by the frictional force generated by the spring-loaded piston 20 held.

As soon as the fault in the brake circuit has been eliminated and the pressure difference to an amount less than the predetermined value is brought back, the prevailing pressure in the chamber 3, which is then over the full effective area of the membrane, is overcome 8 is effective, the frictional force generated by the spring-loaded piston 20, and the unit is in its in the Drawing shown central position reset to switch off the display device again. This movement is supported by the elasticity of the membranes 8 and 9.

The display devices are preferably connected to the ignition circuit of the vehicle and can thus operated when the ignition switch is in the EIF position.

To check the operability of the warning device actuator, i.e. to determine whether the switch 23 works and whether the piston 20, which is preferably made of a non-metallic material, is freely movable, the lever 17 can be pivoted either directly by hand or via a mechanical actuator will.

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In a further embodiment of the invention, the lever 17 to check the actuating device for the warning device can be actuated indirectly by an electrical relay be that can be controlled with a switch arranged for example in the driver's cab of the vehicle.

In the modified embodiment of the actuating device for a pressure difference warning device shown in FIG. 3 the housing 1 has a longitudinally directed blind bore 30, in the bore extension 31 of which a sleeve 32 is received, which forms part of the housing 1 and in which the piston 7 is displaceably guided. The open end of the Bore extension 31 is threaded, in a threaded plug 33 is screwed in. This acts on the sleeve via a clamping ring 34 provided with openings and presses it against a shoulder 35 at the diameter transition between the blind bore 30 and the bore widening 31 at. The membranes 8 and 9 are received in recesses formed in the ends of the sleeve 32 and are on their outer peripheral edges between one end of the sleeve 32 and the shoulder 35 or between the opposite end of the sleeve 32 and a curved contact surface 36 on the clamping ring 34 clamped in a sealing manner.

The lever 17 is received in a bore 38 extending transversely through the sleeve 32 and has on the one facing away from the switch 23 At the end of a head which is substantially elliptical in cross section and which has a head located in the bore 38 Tilt support 39 for the lever 17 forms.

The lever 17 acts on a spring-loaded contact piece 40 which is located in the bore extension 21 of the housing 1 Is displaceably guided and for actuating the warning device in the manner described above with a second Contact piece 41 can be brought into electrical connection as soon as the piston 7 is moved out of the central position and the lever 17 is consequently pivoted about the tilting support 39 in the housing 1.

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Structure and mode of operation of the embodiment shown in FIG. 3 are otherwise the same as in the embodiment according to FIGS. 1 and 2.

The actuating device shown in FIG. 4 for a pressure difference warning device has a housing 50, in which a longitudinal through hole 51 is formed in which a piston 52 operates. The bore is at opposite ends with bore widenings

53 and 54 are provided for receiving a membrane 56 and 57, respectively. the Diaphragms 56 and 57 act on opposite ends of the piston 52 and are conically deformable at radially slotted annular support plates 58 and 59 supported on a shoulder 60 and 61, respectively, at the diameter transitions between the bore 51 and the bore widening 53 or

54 are present. At the inner circumferential edges of the support plates 58 and 59, pin-shaped lugs 62 and 63 of smaller diameter are received at the free ends of the piston 52. Everyone Approach 62 or 63 has a length which is essentially the same is the thickness of the support plate 58 or 59 »so that in one central position of the piston 52 free ends of the same flush with the outwardly facing end faces of the support plates Complete 58 and 59.

The outer peripheral edges of the membranes 56 and 57 are sealed to the associated support plate 58 and 59 and close whose outer circumference & cante pressed by locking pieces 64 or 65, with which the bore extensions 54 and 54 are closed. The locking pieces 64 and 65 form with the membranes 56 and 57 chambers, with which separate circuits of a hydraulic two-circuit brake system via connections 66 and 67 are connectable.

The housing 50 has a radial threaded bore 68, which opens at its inner end at right angles into the bore 51 and a display device 69 in the form of a electrical switch for actuating a warning device

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records. An actuator 70 for the display device 69 engages in an annular groove 71 formed in the piston 52, which is formed with inclined groove walls. In the drawn central position, in which both diaphragms 56 and 57 are acted upon with substantially the same pressure, is the display device 69 in an OFF position and the Warning device is switched off.

If the difference between the different acting on the piston 52 via the membranes 56 and 57 exceeds Print a predetermined value, for example in the event of failure or malfunction of the brake circuit connected to connection 66, then the pressure acting on the opposite end of piston 52 via diaphragm 57 causes a Expansion of the central part of the membrane 57, which is deformed relative to the support plate 59 and through it, as follows that the piston 52 moves in the bore 51 and the display device 69 is actuated.

In this movement of the piston 52, the membrane 56 and the support plate 58 go with it, the support plate 58 becoming conical deformed in order to facilitate deformation of the membrane 56 with the least possible elongation or stretching.

The frictional engagement between the actuating member 70 and the piston 52 places the latter in the displaced position held so that the warning device remains actuated after the end of the braking cycle until the fault in the brake circuit is fixed.

After the malfunction has been eliminated, both membranes 56 and 57 are activated again when the brake is actuated for the first time applied substantially the same pressure. Since the pressure at port 66 acts on a larger effective area than that Pressure at connection 67, namely to substantially the entire Area of the membrane 56 compared to the smaller extension 63

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of the piston 52, a resultant total force acts in one direction on the piston 52 in which it is in the central position is brought back; this total force is sufficient to overcome the frictional engagement. During this Process is ensured by the presence of the support plate 58 that the membrane 56 over its entire effective area is pressurized.

/ Claims

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Claims (7)

1A-46,744 PATENT CLAIMS 1. Actuating device for a pressure difference warning device, which determines when there is a pressure difference between the brake circuits of a hydraulic dual-circuit brake system exceeds a predetermined value, with one disposed in a housing and at opposite ends with the pressure applied to the brake circuits pressure unit and a display device, which by the unit can be actuated when the pressure difference that the unit is exposed, exceeds the predetermined value, and is automatically rendered ineffective when the pressure difference on an amount is reduced which is smaller than the predetermined value, characterized in that the aggregate one in a bore (2; 37; 51) in the housing (1; 50) working piston (7; 52) and a pair in the axial direction in Having spaced apart flexible membranes (8,9; 56,57) on opposite ends of the piston (7; 52) act on their end faces facing away from the piston (7; 52) with the pressures prevailing in the brake circuits can be acted upon and have effective areas which are larger than those of the piston (7; 52), but normally, when the unit assumes a central rest position and the pressure difference is less than the predetermined value, with, with respect to the piston (7; 52), radially outwardly located areas at opposite ends of the bore (2; 37; 51) located walls (11,12; 60,61) of the housing (1; 50) rest so that the effective surfaces of the ends of the Aggregates are equal to the effective areas of the piston (7; 52), wherein when the pressure difference exceeds the predetermined value exceeds, the piston (7; 52) adjusted by one of the diaphragms (8 or 9; 56 or 57) with respect to the bore (2; 37; 51) / 2 509884 / O87Λ -if- 46 744 is and the display device (23 »69) is actuated, this Membrane (8 or 9; 56 or 57) penetrates into the corresponding end of the bore and the other membrane (9 or 8; 57 or 56) from the wall (11 or 12; 60 or 61) on the opposite Bore end is urged away so that it is acted upon over its entire effective area of pressure, and after Falling the pressure difference to an amount less than the predetermined value the force, which from which to the full effective Surface of said other membrane (9 or 8; 57 or 56) acting pressure is exerted on the unit, the Resets the unit to the central rest position and the display device (23; 69) is switched off. 2. Actuating device according to claim 1, characterized in that the piston (52) directly acts on the display device (69). 3. Actuating device according to claim 1, characterized in that the piston (7) has a Lever mechanism (17) acts on the display device (23). 4. Actuating device according to claim 3 »characterized in that the lever mechanism is a Lever (17) which is pivotable at one end about a tilting support (18; 39) in the housing (1) and at one end between its At the ends located point with a tilting bearing ring (22) engages pivotably and slidably on the piston (7), as well as a has elastic device (19) which acts on the opposite end of the lever (17) and a friction force which holds the piston (7) in the position it assumes when the pressure difference reaches the predetermined value exceeds. 5. Actuating device according to claim 3 or 4, characterized in that the display device a warning device and an electrical safety holder (23) which actuates this and which has an adjustable contact piece (40), / 3 509884/0874 -X- 46 on which the lever (17) engages, and has a spring which engages the adjustable contact piece (40) with a fixed contact piece (41) is able to bring to actuate the warning device a Close the circuit as soon as the lever mechanism (17) depends on the movement of the unit from the aforementioned central rest position has gone out into a working position. 6. Actuating device according to one of claims 1 to 5, characterized in that the membranes (56, 57) each have a conically deformable support plate (58 or 59) are supported, which via the associated membrane (56 or 57) with an outer peripheral edge to the Wall are pressed against the associated end of the bore (51). 7. Actuating device according to claim 6, characterized in that both support plates (58,59) Are ring-shaped, at their inner peripheral edges smaller in diameter peg-shaped lugs (62,63) to the Receiving ends of the piston (52), and are radially slotted to facilitate the conical deformation. 509884/0874