DE102011106629A1 - Control cylinder for an engine brake with means for generating a springback - Google Patents

Abstract

The invention relates to a control cylinder (12) for an engine brake to create a deceleration function by throttling the exhaust gas flow on the outlet side of a turbocharger (2) of a vehicle engine (1), comprising a cylindrical housing (13) for accommodating a piston (14) with a piston rod (15 ) for dividing the housing (13) into - a spring chamber (16) for accommodating a return spring (17) for the piston rod (21), and - a pressure chamber (18) for generating an actuating force by the piston (14) by compressed air, wherein - the piston (14) cooperates with means for producing a springback, the means for producing the springback within the cylindrical housing (13) being designed as an elastic spacer between the piston (14) and the piston rod (15).

Description

Field of the invention

The invention relates to a control cylinder for an engine brake for generating a deceleration function by throttling the exhaust gas flow outlet side of a turbocharger in a vehicle engine, comprising a cylindrical housing for housing a piston with piston rod, which the cylindrical housing in a spring chamber for accommodating a return spring for the piston rod and a Pressure chamber for generating an actuating force for the piston divided by compressed air, wherein the piston cooperates with means for generating a springback.

Pneumatic cylinders of this type are used, for example, in commercial vehicle technology to actuate valves arranged on the outlet side of a turbocharger of diesel engines. The engine brake control cylinder generates a linear closing and opening force for an operating lever of the valve that is inserted into the exhaust gas exhaust passage of the turbocharger. The control cylinder of the engine brake generates the closing force for the valve by compressed air provided by the vehicle. The return spring and exhaust back pressure defines the opening force for the valve.

Background of the invention

The publication JP 08261021 A discloses a control cylinder for an engine brake, which is designed as a single-acting pneumatic cylinder of the type described above. In the warm-up mode, in which a warm-up switch is turned on, compressed air regulated by pressure regulating means at a low pressure level is introduced into the control cylinder of the engine brake to move the inner piston only against the internal compression spring and stop where a slider comes in contact is brought with a spring support surface. In this position, the connected engine brake valve is closed, so that only a part of the exhaust gas can pass through this.

On the other hand, when the vehicle is in normal operation and the engine brake is operated, the piston of the engine brake control cylinder moves against first and second compression springs due to high-pressure-regulated compressed air and stops at a position where a protector contacts the slider comes to completely close the connected engine brake valve.

According to the generally known state of the art, an intermediate element with a prestressed spring and axial return spring means is used in the power flow between the piston rod of the control cylinder and a lever actuating the engine brake valve. The intermediate element allows a limited return opening of a throttle valve of the engine brake valve by way of a limited springback at undesirably high pressure in the exhaust pipe. However, this additional intermediate element requires a correspondingly large installation space and increased parts and assembly costs.

It is therefore an object of the present invention to provide means for generating a springback between the piston rod of the control cylinder and the engine brake valve, which consists of a few. There are individual parts and are made small-sized.

Brief description of the invention

The object is achieved on the basis of a control cylinder according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims give advantageous developments of the invention.

The invention includes the technical teaching that special means for generating the springback within the cylindrical housing of the control cylinder are arranged.

The inventive means for generating the springback can be realized according to different - described in detail below - embodiments, in principle, the function of the aforementioned intermediate element is realized within the control cylinder in which a mutually relative movement of the piston rod and the piston takes place and between the two components elastic spacers are formed of different types. The elastic spacers are dimensioned so that the relative movement between piston rod and piston only at undesirably high pressure, d. H. If too much force of the throttle valve is created. This relative movement between the piston rod and piston allows for a limited travel rear opening of the throttle valve, whereby the pressure in the exhaust pipe is reduced so far that the engine braking effect is still sufficient, but the reduced pressure can no longer lead to engine damage.

According to a first preferred embodiment, the means for generating the springback comprise a prestressed spring arranged within the cylindrical housing, which acts on the one hand on the piston rod and on the other hand on the piston. The spring may be formed as a compression spring made of spring steel, which has an on the piston rod mounted disc is coupled from the piston rod. On the other side, the spring can come coaxially on the piston end face to the plant.

According to a measure improving this embodiment, it is proposed that the spring travel of the spring is adjustable by means of an adjusting screw acting thereon. Further, the piston rod should be longitudinally slidably guided relative to the piston, for example, be plugged end into a corresponding coaxial recess of the piston.

According to another embodiment, the means for generating the springback comprise a compressed air spring housed within the cylindrical housing, which acts on the one hand on the piston rod and on the other hand on the piston. Such a pneumatic spring, for example, consist of a piston integrated in the cylindrical working space, which cooperates with a piston arranged therein, on which the piston rod is mounted.

According to a measure improving this embodiment, it is proposed that the cylindrical working space can be ventilated via a pressure limiting valve in order to maintain the return opening force of a throttle valve provided for engine braking at a constant tolerance range for all actual actuating pressures.

Furthermore, the cylindrical working space can also be connected via a discharge valve to the environment in order to limit the pressure in the working space to a maximum value.

The control cylinder according to the invention should be protected by the spring chamber against contamination to ensure a long service life, in particular the valve technique described above. In this regard, the piston rod relative to the cylinder cover of the cylindrical housing can be sealed with a seal according to another measure improving the invention, wherein in the cylinder cover an outwardly leading check valve is arranged to dissipate excess pressure from the spring chamber to the environment. Further, in the piston, a refill valve can be integrated, which is arranged between the spring chamber and the pressure chamber. The refill valve prevents low pressure in the spring chamber, which would cause, inter alia, a suction effect for impurities from the outside.

Further measures improving the invention will be described in more detail below together with the description of the preferred embodiments with reference to the figures. It shows:

1 a schematic representation of a turbocharger assembly of an automotive engine with exhaust brake system,

2 a perspective view of throttle means of the engine brake system of the turbocharger after 1 .

3a to 3c a first embodiment of the means for generating the springback within a control cylinder at different positions of the piston rod,

4 a further embodiment of the means for generating the springback within a control cylinder,

5 a third embodiment of the means for generating the springback within a control cylinder,

6 a modification of the embodiment according to 5 in terms of valve technology, which interact with the means for generating the springback, and

7 a further modification embodiment according to 5 in terms of valve technology, which interact with the means for generating the springback.

The reference numerals in the drawings and their meaning are indicated in the list of reference numerals. In principle, the same components are provided with the same reference numerals in the figures.

Detailed Description of the Preferred Embodiments

According to 1 is a vehicle engine 1 with a turbocharger 2 fitted. The turbocharger 2 includes a turbine part 3 Mechanically with a compressor part 4 via an intermediate drive shaft 5 connected is. The exhaust from the vehicle engine 1 is through an exhaust pipe 6 to the turbine part 3 of the turbocharger 2 over an inlet 7 directed. The exhaust gas flow causes a rotation of the drive shaft 5 to the compressor part 4 drive. The compressor part 4 sucks through an air intake 8th Fresh air from the atmosphere to this via an inlet pipe 9 Air inlet side of the vehicle engine 1 to provide.

In addition, in the area of an exhaust outlet 10 of the turbocharger 2 Engine braking means arranged, which an exhaust brake valve 11 comprises, which is designed in the manner of a flap valve. The exhaust brake valve 11 is by a control cylinder 12 the engine brake is actuated to a deceleration function by throttling the exhaust flow discharge side of the turbocharger 2 in the area of the exhaust outlet 10 bring about.

With regard 2 becomes the engine brake valve 11 in the exhaust outlet 10 by a lever for implementing the linear movement of the control cylinder 12 the engine brake in a rotational movement for actuating the engine brake valve 11 connected. This is the control cylinder 12 the engine brake is pivotally mounted on a support frame leading to one end of the control cylinder 12 the engine brake is arranged.

To 3a includes the control cylinder 12 a cylindrical housing 13 to accommodate a piston 14 with the piston rod departing therefrom 15 , The piston 14 divided the housing 13 in a spring chamber 16 for accommodating a return spring 17 for the piston rod 15 and a pressure chamber 18 for generating an actuating force by the piston 14 by compressed air.

When the pressure chamber 18 over the outer connection 19 is pressurized, the piston moves 14 starting from the illustrated basic position together with the displaceable piston rod 15 up to the full stroke, as in 3b shown. The relative position of the piston rod 15 to the piston 14 is by a spring housing 20 attached to the piston rod 15 attached disc 21 and by a preloaded spring 22 certainly.

When an undesirably high pressure occurs in the exhaust port (not shown), the throttle valve of the engine brake valve arranged therein is loaded by the pressure with a torque in the opening direction and the piston rod 15 is loaded with an increased restoring axial force. When this axial force is greater than the force of the preloaded spring 22 becomes, becomes the piston rod 15 against the spring 22 pushed back so far that the disc 21 on a heel of the piston 14 impacts. So the situation is according to 3c realized in which the piston rod 15 completely pushed back. The pushed back path depends on the parts and is not adjustable. The feather 22 is preloaded according to the allowed maximum closing force of the throttle or the maximum allowable pressure in the exhaust pipe.

According to 4 is the travel of the means for generating the springback via an adjusting screw 23 adjustable. The adjusting screw 23 is the front side of the piston rod 15 screwed. The head of the adjusting screw 23 forms with one on the piston 14 formed within a coaxial recess paragraph an end stop. The adjusting screw 23 is during assembly of the control cylinder 13 and should be secured with glue or the like. The by screwing the adjusting screw 23 in the piston 14 required mounting hole is with a sealing washer 24 locked.

At the in 5 Other embodiments shown include those between pistons 14 and piston rod 15 arranged means for generating the springback a pneumatic spring, which from one end of the piston rod 15 attached pistons 25 and one side of the piston 14 of the control cylinder 12 ' trained cylindrical workspace 26 consists. The workroom 26 stands through an opening 27 one in the piston 14 firmly inserted disc 28 with the pressure chamber 18 of the control cylinder 12 in pneumatic connection. On the working surfaces of the piston 14 as well as the inner piston 25 thus acts the same within the pressure chamber 18 applied pressure. The diameter of the piston 14 is to be dimensioned so that the force exerted by pressurization force is greater than the spring force of the return spring 17 and the actuating force of the - not shown here - throttle valve of the engine brake valve. The diameter of the inner piston 25 is to be dimensioned such that the force applied as a result of pressurization is equal to the return opening force of the throttle valve of the engine brake valve.

To the push-back force of the piston rod 15 To keep at a nearly constant value, the actuating pressure of the control piston 12 ' be kept within narrow limits. Since the actuation pressure between switch-on pressure and switch-off pressure of the air supply system may change, even in a special case may fall to a backup pressure, it is advantageous if the actuation pressure is below the operating pressure range.

According to 6 Such an actuation pressure via a pressure relief valve 29 secured. Through the pressure relief valve 29 For example, sufficient deceleration braking effect can be achieved even when the operating pressure is relatively low. The pressure relief valve 29 serves to ventilate the cylindrical working space 26 the air spring and is in the piston 14 of the control cylinder 12 ' arranged. The pressure relief valve 29 is set up in the workroom 26 an actuation pressure is ensured, which is below the real operating pressures. Furthermore, the cylindrical working space 26 about one in the piston 25 integrated drain valve 30 connected with the environment to the pressure in the work space 26 to limit to a maximum value. The drain valve 30 represents z. B. is a check valve with an increased opening pressure to the pressure from the working space 26 the air spring in the spring chamber 16 drain. In this case, the diameter of the work space must be 26 be dimensioned so that the desired Rear opening force of the throttle valve at the opening pressure of the blow-off valve 30 is not exceeded.

With regard to 7 is the piston rod 15 opposite a cylinder cover 31 of the cylindrical housing 13 with a seal 32 sealed. In the cylinder cover 31 is an outwardly leading check valve 33 arranged to overpressure from the spring chamber 16 dissipate to the environment. As a result, the spring chamber 16 protected against external pollution.

In the piston 14 is also a refill valve 34 integrated, that between the spring chamber 16 and the pressure chamber 18 is arranged. Through the refill valve 34 becomes the working chamber 18 only with the spring chamber 16 connected when the pressure difference below a limit - for example, 1.6 bar - is.

The refill valve 34 can be performed on the part of the valve body as Elastomerbauteil. The refill valve 34 prevents dirt from the outside in the spring chamber 16 is sucked in, as in return movement of the piston 14 the spring chamber volume is larger, resulting in a low pressure below the atmospheric pressure in the spring chamber 16 leads. The low pressure prevents the return movement of the piston 14 and creates a suction effect, which allows dirt to be sucked from the outside. By the per refill valve 34 this is no longer to be feared.

LIST OF REFERENCE NUMBERS

1

vehicle engine

2

turbocharger

3

turbine part

4

compressor part

5

drive shaft

6

exhaust pipe

7

exhaust inlet

8th

air intake

9

inlet pipe

10

exhaust outlet

11

Engine brake valve

12

control cylinder

13

casing

14

piston

15

piston rod

16

spring chamber

17

Return spring

18

pressure chamber

19

connection

20

spring housing

21

disc

22

feather

23

adjustment

24

sealing washer

25

piston

26

working space

27

opening

28

disc

29

Pressure relief valve

30

drain valve

31

cylinder cover

32

poetry

33

check valve

34

refill

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 08261021 A [0003]

Claims (11)

Control cylinder ( 12 ) for an engine brake to provide a deceleration function by throttling the exhaust gas flow on the outlet side of a turbocharger ( 2 ) of a vehicle engine ( 1 ) comprising a cylindrical housing ( 13 ) for accommodating a piston ( 14 ) with a piston rod ( 15 ) for a subdivision of the housing ( 13 ) in a spring chamber ( 16 ) for accommodating a return spring ( 17 ) for the piston rod ( 21 ), and - a pressure chamber ( 18 ) for generating an actuating force by the piston ( 14 ) by compressed air, wherein - the piston ( 14 ) cooperates with means for generating a springback, characterized in that the means for generating the springback within the cylindrical housing ( 13 ) as elastic spacers between pistons ( 14 ) and piston rod ( 15 ) are formed. Control cylinder according to claim 1, characterized in that the piston rod ( 15 ) longitudinally displaceable relative to the piston ( 14 ) is guided. Control cylinder according to claim 1, characterized in that the means for generating the springback a within the cylindrical housing ( 13 ) biased spring ( 22 ), on the one hand to the piston rod ( 15 ) and on the other hand on the piston ( 14 ) acts. Control cylinder according to claim 3, characterized in that the spring designed as a compression spring ( 22 ) via one on the piston rod ( 15 ) attached disc ( 21 ) to the piston rod ( 15 ) is coupled. Control cylinder according to claim 3, characterized in that the spring travel of the spring ( 22 ) via an adjusting screw acting thereon ( 23 ) is adjustable. Control cylinder according to claim 1, characterized in that the means for generating the springback a within the cylindrical housing ( 13 ) accommodated compressed air spring, on the one hand to the piston rod ( 15 ) and on the other hand on the piston ( 14 ) acts. Control cylinder according to claim 1, characterized in that the compressed air spring from a in the piston ( 14 ) integrated cylindrical working space ( 26 ) provided with a piston (herein) 25 ) cooperates, on which the piston rod ( 15 ) is attached. Control cylinder according to claim 7, characterized in that the cylindrical working space ( 26 ) via a pressure relief valve ( 29 ) is capable of being ventilated to provide the return force of a throttle valve ( 11 ) to be kept in a constant toleration range at all real actuation pressures. Control cylinder according to claim 8, characterized in that the cylindrical working space ( 26 ) via a drain valve ( 30 ) is connected to the environment in order to reduce the pressure in the working space ( 26 ) to a maximum value. Control cylinder according to one of the preceding claims, characterized in that the piston rod ( 15 ) relative to a cylinder cover ( 31 ) of the cylindrical housing ( 17 ) with a seal ( 32 ) is sealed, wherein in the cylinder cover ( 31 ) an outwardly leading check valve ( 33 ) is arranged to overpressure from the spring chamber ( 16 ) dissipate to the environment. Control cylinder according to one of the preceding claims, characterized in that a refill valve ( 34 ) in the piston ( 14 ) is integrated between the spring chamber ( 16 ) and the pressure chamber ( 18 ) is arranged.

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