DE2324334A1 - DOUBLE CIRCUIT COMPRESSED AIR BRAKE DEVICE - Google Patents

Description

ί 4 6 8

April 17, 1973 Ke / Hö

Attachment to

Patent and. ",,,"

Utility model ^{auxiliary registration} S

ROBERT BOSCH GMBH, Stuttgart dual-circuit compressed air brake device

The invention relates to a dual-circuit pneumatic braking device with two working pistons lying one behind the other, of which the first one lying between it and a cylinder base bounds the first working chamber and the second forms the wall of a second working chamber between the first and the second working piston is, and with two consecutive control valves, of which the second through the from the first controlled pressure is actuated and which monitor the compressed air supply of the two working chambers by the Connect working chambers either to an outside air connection or to a supply air connection and in a valve center Partially lock or partially open both connections.

Such a braking device is known (CH-PS 525 107). at such fire devices it can happen that the seals the working piston will be defective. If the seal of the second working piston leaks, the air blows to it anyway Outside air connected to the counter spring side of the working piston, and the driver is on by the strong blow-out noise the error attentively. But if the seal of the first working piston leaks, this happens during the partial braking position the following:

409849/0437 " ² ~

Robert Dosch GmbH R.

Stuttgart April 17, 1973 He / Hö

Since the first control valve is usually mechanical and the second control valve actuated by the pressure applied by the first control valve the compressed air injected from the first control valve into the first working chamber flows over the defective seal of the first piston into the second working chamber located between the two working pistons. From there the compressed air reaches the still the outside air connection keeping open second control valve in the Outside air connection and blows off audibly there, since primary and secondary side The same pressure build-up takes place on the second control piston, and the necessary excess force (pressure difference) for closing the outlet seat is not reached. This can result in insufficient Subsequent delivery by the air compressor in the event of a longer partial burn (Going downhill, idling) the supply of circuit I is exhausted. A corresponding reduction in the braking force occurs, see above that when the supply I is exhausted no more braking force on the Circle I can be reached. In order to generate braking force again, the second circuit must be mechanically operated and grounded, with the inlet of the first control valve is inevitably opened. About the broken Sealing ring on the first working piston, the supply air flows from circuit II into circuit I and fills it until the pressure is equalized with Krais II. The total pressure level drops by half:

1. through the process already described above and

2. in the case of repeated braking operations carried out in quick succession.

The invention is based on the object of avoiding this disadvantage and a two-circuit compressed air Brensgerät mentioned above To create a way in which no loss of supply can occur in the second brake circuit even if the first piston seal fails. This object is achieved according to the invention in that in the Supply air connection of the first working room one in the direction The non-return valve closes on the reservoir of the first Brsrr.s is used.

409849/0437

Robert Bosch SrnbH '^ "R.

Stuttgart 17.4.1: -73 Hb / Hö

An example embodiment of the invention is shown in the drawing namely show:

Fig. 1 the dual-circuit compressed air braking device in partial braking position with existing supply I with failed first piston seal and

Fig. 2 the Bruvnsgerät in the partial burning position with empty reservoir I.

A dual-circuit compressed air braking device 1 has a multi-part housing, that essentially consists of a working cylinder 2 and a Valve part 3 consists. The working cylinder 2 is formed by a cup-shaped housing piece 4 with a cover 5, and the valve part 3 has a valve housing 6 attached to the working cylinder 2,. the free side of which is covered by a cap 7 which is used for receiving a pressure piece 8 is hollow and has a dust protection bellows 9 is sealed.

The valve housing 6 is used to accommodate two double seat valves trained control valves 10 and 11 for the two Breras circuits. It is on both sides with and equidistant in diameter the same holes 12 and 13 are provided. In between, the valve housing 6 has a body 14, which is in a behind the sectional plane lying level a VorratsanschluQ 15 the first focal circuit as well as an outside air connection 16 carries. A supply connection 17 of the second fuel circuit is also on the valve housing 6 provided, but it opens into the axial bore 13 and is continued there in a floating in the valve housing 6 arranged chamber 18. This chamber 18 is an annular space in a longitudinally movable 5 control piston 19 in the bore 13, which carries the inlet valve seat of the second control valve 11 on the inside. The control piston 19 usually lies on the body 14 under the force of a spring 19 ', as in the one below the central axis lying half of the braking device can be seen. The feather 19 'is housed in a pressure change chamber 19' ', the

409849/0437

Robert Booch GmbH R.

Stuttgart April 17, 1973 He / Ho

further connection will be described later.

The outlet valve seat of the second control valve 11 is connected to the Working cylinder bottom 21 arranged. In a central recess 22 of the working cylinder base 21 is a guide sleeve 23 for the first working piston 20 is used pivotably and sealed by a D-ring. For the axial attachment of the sleeve 23 on Working cylinder base 21, the sleeve is provided with a double annular collar 26, which is formed by an annular collar 26 that is let into the recess 22 .Sprengring 27 is held. The pressure change space is 19 " through the guide sleeve 23 with a working space lying between the first 2D and a second working piston 24 24 'of the second working piston 24 connected.

Deide pistons 20 and 24 are in the rest position with a small distance to each other. They are in the cylinder at their outer diameter guided. The first piston 20 has an O-ring 42 as a piston seal and a bearing neck 20 ″, which slides on the guide sleeve 23 fixed in the bottom 21 of the working cylinder 2 and which due to its dimensions prevent the piston 2G from clogging.

The second working piston 24 has a sleeve seal 43 as Piston seal and a partially hollow piston rod 28 with a ball end 20 '. The piston rod 20 is with the ball end 28 'in a hydraulic, not shown, arranged downstream of the Brsnsgerät Master cylinder in storage. In this way, the working piston 24 is also given a guide.

On the control piston 19 a sleeve 29 is attached inside, which with the inner end of the pressure piece to be operated by the pedal coupled via a spring 30 and a bolt 40 with axial play is. The bolt 40 penetrates the control valve 10. The bolt 40 is in a feedback piston 31 of the first double seat valve 10 inserted coaxially and screwed to the piston 31.

. 409849/0437

Stuttgart April 17th, 1973 He / Hö

The reaction piston 31 is inserted into the bore 12 so that it can move longitudinally and is sealed. A pressure change space 32 behind the reaction piston 31 is connected via a channel 33 in the valve part 3 to a space 34 in front of the control piston 19 of the second control valve 11. In addition, an initially radial, then axially parallel channel 35 is connected to the pressure change chamber 32 and leads in the valve housing 6 and through the base 21 of the working cylinder 4 to a working chamber 20 ¹ located in front of the first working piston 20. The two pistons 31 and 19 have the same outer diameter and the same outer surface.

A forward line leads to the supply connection 15 Check valve 41 is used, which in the direction of the reservoir closes.

The braking device described works as follows:

In the rest position, both working rows 20 'and 24' are without Pressure. If, during braking, the pressure piece B and, via the displacement spring 30, the piston 31 are pressed into the braking device, then first the first double seat valve 10 changed over, so that supply air from the connection 15 into the pressure change chamber 32 and from there over the channel 35 enters the work space 20 '. A pressure build-up takes place but also via channel 33 in space 34. The control piston 19 with the floating chamber 1Q is released against the force the spring 19 'from the body 14, and the second double seat valve 11 also switches over. Arrived from the supply connection 17 Compressed air through the floating chamber 1B into the pressure change space 19 "and from there through the bottom 21 and the sleeve 23 into the Workspace 24 ·. The same pressure on both sides of the booster piston 20 would in itself cause the piston 20 to stop. Since, however, the spring 19 'when balancing the pressures in the spaces 34 and 19 "causes a lower pressure in space 19" than in space 34, and since there is therefore a higher pressure than prevails in space 20 ' ä, m space 24 ', the working piston 20 is moved along with it. A solid corrosive

409849/0437

Robort Bosch GmbH "^ ' R.

Stuttgart April 17, 1973 He / Hö

Dating the working piston 20 is prevented. The respective eingesteuerta pressure acts on the piston 31 on the fuo the driver back _f se that this sin feel for the time spent Qremskraft has "

If the pressure at the supply connection 15 fails, then when braking the Steusrkalben 19 mechanically controlled by the bolt 4Π. He lays down on the sleeve 29, which has a mechanical connection to the second control valve 11 produces. The second control valve 11 is switched over, and compressed air enters the working space 24 'in front of the working piston 24. This piston 24 then actuates only the brakes. Due to the same calf flesh of the control piston 19 the retroactive effect is the same.

However, if the pressure at the supply connection 17 fails, the remains Working space 24 'without pressure. Now the working cylinder 20 takes over the Actuation of the downstream master cylinder by moving away from the Bottom 21 releases and the working piston 24 moves with it.

However, if the D-ring seal 42 fails as a result of a fault, then at the beginning of the 3renisens the compressed air flows out of the first Breras circle, as the arrows in Fig. 1 show, into the chamber 24 ' between the two working pistons 20 and 24 and arrives from there Via the still open second control valve 11 into the outside air connection 16. Through the blow-off the driver can indeed on the Become aware of the fault in the dual-circuit braking device. But so that the vehicle can still be driven to the workshop, his Braking ability are retained. The check valve now takes care of this 41, although the supply from c.'em first brake circuit via the defective seal 42 can flow off, but this prevents the full supply of the second brake circuit, which is now the only decisive is for the effectiveness of the DremsgerMte up to the pressure equalization can flow back into the first reservoir. Fig. 2 shows the supply air flow through the braking device * he wis in this

- • 7 409849/0437

Robert Ooüch 3r; bH * f ^m R.

Stuttgart April 17, 1973 He / Hö

Fall would take place, but as it did through the closing Rückschlagv3ntil 41 is prevented.

409849/0437

Claims (1)

Robert Oosch GmbH '%' Π. Stuttgart, April 17, 1973 He / Hö Anopruch Two-wheel compressed air braking device with two one behind the other Working pistons, of which the first delimits a first working chamber lying between it and a cylinder base, and the first working chamber second forms the iiand its second working chamber, which lies between the first and the second working piston, and with two mutually aligned Control valves, of which the second is actuated by the pressure introduced by the first and which the Monitor the compressed air supply to the two working chambers by connecting the working chambers either to an outside air connection or Connect to a supply air connection and partially shut off both connections in a valve center position, respectively partially open, characterized in that in the supply air connection of the first working space (20) in the direction of the Reservoir of the first brake circuit closing check valve (41) is used. 409849/0437 Blank page