EP2721274B1 - Control cylinder for an engine brake having means for generating a spring-back - Google Patents

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 applied, the piston of the control cylinder of the engine brake 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.

Furthermore, goes from the DE 699 05 112 T2 a arranged in an exhaust pipe brake device of a vehicle with internal combustion engine, which has at least one valve with a movable closure device and a control cylinder of the closure device. The control cylinder comprises a cylindrical housing for accommodating a piston with a piston rod. The piston divides the housing into a spring chamber for accommodating a spring for the piston rod, and a pressure chamber for generating an actuating force by the piston by means of compressed air. The piston rod is guided longitudinally displaceable relative to the piston. A balancing device is housed in the control cylinder, and disposed between the movable piston and the rod of the piston. The balancing device comprises a biased spring disposed within the cylindrical housing, which acts on the one hand on the piston rod and on the other hand on the piston.

In addition, the reveals WO 2009/103561 A1 an exhaust gas control system having an exhaust throttle valve in an exhaust passage, an actuator of the exhaust throttle valve with an actuating linkage and an exhaust pressure control device of the exhaust gas pressure occurring upstream of the exhaust throttle valve in the exhaust passage. The actuating linkage has a Regelaktuatorik which cooperates with a pressure compensation volume, wherein the pressure compensation volume is pneumatically connected to a throttle opening upstream of the exhaust throttle valve.

The EP 0 872 646 A1 discloses a compressed air cylinder for actuating the exhaust flap of an engine brake, the first end face is fixed and pivotally mounted. Furthermore, a piston rod of a piston displaceable in a cylinder housing exits from its opposite second end face. The piston rod is connected to an actuating mechanism, preferably an axis of an exhaust flap of an engine brake via a flap lever. An outer channel is provided for supplying and discharging compressed air, wherein this via a connecting channel with the cylinder housing connected is. A retainer is provided for the piston in the retracted position and a retraction means is provided for the piston from the extended to the retracted position. The retractor consists of a pressure chamber, with a feed channel and a discharge channel having an inlet valve and a discharge valve, respectively, which communicate with the outer channel. The pressure chamber can be filled via the supply channel and the inlet valve simultaneously with the cylinder housing with compressed air. Further, the pressure chamber after the pressure relief of the cylinder housing on the outer end face of the piston exert pressure such that it is pressed in retracted position.

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 consist of a few individual parts and are designed to be physically small.

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 arises only at undesirably high pressure, ie at too high a force of the throttle. 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 is coupled via a mounted on the piston rod disc side of 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 on the part of the spring chamber against contamination to a long service life, in particular the above-described Valve technology, to ensure. 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.

Figur 1

eine schematische Darstellung einer Turboladeranordnung eines Kraftfahrzeugmotors mit Auspuffbremsanlage,

Figur 2

eine perspektivische Ansicht von Drosselmitteln der am Motorbremseanlage des Turboladers nach Figur 1,

Figur 3a bis Figur 3c

eine erste Ausführungsform der Mittel zur Erzeugung der Rückfederung innerhalb eines Steuerzylinders bei unterschiedlichen Stellungen der Kolbenstange,

Figur 4

eine weitere Ausführungsform der Mittel zur Erzeugung der Rückfederung innerhalb eines Steuerzylinders,

Figur 5

eine dritte Ausführungsform der Mittel zur Erzeugung der Rückfederung innerhalb eines Steuerzylinders,

Figur 6

eine Modifikation des Ausführungsbeispiels nach Figur 5 hinsichtlich Ventiltechnik, die mit den Mitteln zur Erzeugung der Rückfederung zusammenwirken, und

Figur 7

eine weitere Modifikation Ausführungsbeispiels nach Figur 5 hinsichtlich Ventiltechnik, die mit den Mitteln zur Erzeugung der Rückfederung zusammenwirken.

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:

FIG. 1

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

FIG. 2

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

FIG. 3a to FIG. 3c

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

FIG. 4

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

FIG. 5

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

FIG. 6

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

FIG. 7

a further modification embodiment according to FIG. 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 FIG. 1 a vehicle engine 1 is equipped with a turbocharger 2. The turbocharger 2 comprises a turbine part 3, which is mechanically connected to a compressor part 4 via an intermediate drive shaft 5. The exhaust gas from the vehicle engine 1 is passed through an exhaust pipe 6 to the turbine part 3 of the turbocharger 2 via an inlet 7. The exhaust gas flow causes rotation of the drive shaft 5 to drive the compressor part 4. The compressor part 4 sucks fresh air from the atmosphere through an air inlet 8 in order to make it available to the vehicle engine 1 via an inlet pipe 9 on the air inlet side.

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

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

To FIG. 3a The piston 14 divides the housing 13 into 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 is pressurized via the outer port 19, the piston 14 moves from the illustrated basic position together with the displaceable piston rod 15 up to the full stroke, as in FIG FIG. 3b shown. The relative position of the piston rod 15 to the piston 14 is determined by a spring housing 20, attached to the piston rod 15 disc 21 and by a prestressed spring 22.

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 biased spring 22, the piston rod 15 is pushed back against the spring 22 so far that the disc 21 impacts on a shoulder of the piston 14. So the situation is according to Figure 3c realized in which the piston rod 15 completely has been postponed. The pushed back path depends on the parts and is not adjustable. The spring 22 is biased in accordance with the allowable maximum closing force of the throttle or the maximum allowable pressure in the exhaust pipe.

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

At the in FIG. 5 The other embodiment shown arranged between the piston 14 and the piston rod 15 means for generating the springback comprises a pneumatic spring which consists of a piston rod 15 fixed to the piston 25 and a side of the piston 14 of the control cylinder 12 'cylindrical working space 26. The working space 26 is in pneumatic communication with the pressure chamber 18 of the control cylinder 12 'through an opening 27 in a disk 28 which is firmly inserted in the piston 14. On the working surfaces of the piston 14 and 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 exerted due to pressurization is equal to the Rücköffhungskraft the throttle valve of the engine brake valve.

In order to keep the return force of the piston rod 15 to almost constant value, the operating pressure of the control piston 12 'must be kept within narrow limits. Since the Actuating pressure between cut-in pressure and cut-off pressure of the air supply system can change, even in special cases can fall to a backup pressure, it is advantageous if the actuation pressure is below the operating pressure range.

According to FIG. 6 such actuation pressure is secured via a pressure relief valve 29. By the pressure limiting valve 29, a sufficient retarding brake effect can be achieved even when the operating pressure is relatively low. The pressure limiting valve 29 serves to ventilate the cylindrical working space 26 of the pneumatic spring and is arranged in the piston 14 of the control cylinder 12 '. The pressure relief valve 29 is adjusted so that an operating pressure is ensured in the working space 26, which is below the real operating pressures. Further, the cylindrical working space 26 is connected via a built-in piston 25 in the discharge valve 30 with the environment to limit the pressure in the working space 26 to a maximum value. The drain valve 30 represents, for example, a check valve with an increased opening pressure to drain the excess pressure from the working space 26 of the air spring in the spring chamber 16. In this case, the diameter of the working space 26 must be dimensioned so that the desired rearward opening force of the throttle valve is not exceeded at the opening pressure of the blow-off valve 30.

With regard to FIG. 7 the piston rod 15 is sealed with respect to a cylinder cover 31 of the cylindrical housing 13 with a seal 32. In the cylinder cover 31, an outwardly leading check valve 33 is arranged to remove excess pressure from the spring chamber 16 to the environment. As a result, the spring chamber 16 is protected against contamination from the outside.

In the piston 14, a refill valve 34 is further integrated, which is arranged between the spring chamber 16 and the pressure chamber 18. By the refill valve 34 is the Working chamber 18 is only connected to the spring chamber 16 when the pressure difference is below a limit - for example, 1.6 bar -.

The refill valve 34 may be performed by the valve body as Elastomerbauteil. The refill valve 34 prevents dirt from being sucked into the spring chamber 16 from the outside, since during return movement of the piston 14 the spring chamber volume becomes larger, which leads to a low pressure below the atmospheric pressure in the spring chamber 16. The low pressure prevents the return movement of the piston 14 and a suction effect, whereby dirt can be sucked from the outside. This is no longer to be feared due to the pressure compensation brought about by the refill valve 34.

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

Claims (6)

1. Control cylinder (12) for a motor brake for the provision of a deceleration function by throttling the exhaust gas flow on the outlet side of a turbocharger (2) of a vehicle motor (1), comprising a cylindrical housing (13) for the accommodation of a piston (14) with a piston rod (15) for dividing the housing (13) into:

   - a spring chamber (16) for accommodating a spring (17) for the piston rod (15), and

   - a pressure chamber (18) for producing an actuating force by the piston (14) by means of compressed air, wherein

   - the piston (14) co-operates with means for producing a springback, wherein the piston rod (15) is guided and can move longitudinally relative to the piston (14),

   characterized in that the means for producing the springback comprise a compressed air spring accommodated inside the cylindrical housing (13), which spring acts on one side against the piston rod (15) and on the other side against the piston (14).
2. Control cylinder according to Claim 1,
   characterized in that the compressed air spring consists of a cylindrical working space (26) integrated in the piston (14), which co-operates with a piston (25) arranged in it, to which the piston rod (15) is attached.
3. Control cylinder according to Claim 2,
   characterized in that the cylindrical working space (26) can be ventilated by a pressure-limiting valve (29), in order to keep the back-opening force of a throttle valve (11) provided for motor braking within a constant tolerance range at all real operating pressures.
4. Control cylinder according to Claim 3,
   characterized in that the cylindrical working space (26) communicates with the surroundings via an outlet valve, in order to limit the pressure in the working space (26) to a maximum value.
5. Control cylinder according to Claim 1,
   characterized in that the piston rod (15) is sealed relative to a cylinder cover (31) of the cylindrical housing (13) by a seal (32), and in the cylinder cover (31) an outward-leading one-way valve (22) is arranged, in order to bleed excess pressure out of the spring chamber (16) to the surroundings.
6. Control cylinder according to Claim 1,
   characterized in that a replenishing valve (34) is integrated in the piston (14), which is arranged between the spring chamber (16) and the pressure chamber (18).

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