AN APPARATUS FOR DAMPING PRESSURE PULSATION FOR A COMPRESSOR OF A GASEOUS FLUID

Abstract

An apparatus for damping pressure pulsation for a compressor of a gaseous fluid in a refrigerant circuit including a housing with an inlet opening and at least one first outlet opening and a piston element movable in an axial direction within a volume enclosed by the housing and supported on the housing in a beared manner via a spring element, wherein the piston element respectively controls a flow cross section of the inlet opening and the first outlet opening, wherein the piston element and the housing have at least one first sealing surface and a second sealing surface. The first sealing surfaces form a first seat and the second sealing surfaces form a second seat, wherein between the seats, one chamber enclosed by the housing and the piston element for expanding the fluid when flowing into the chamber and/or at least one second outlet opening in the housing is formed.

Claims

1-15. (canceled)

16. An apparatus for damping pressure pulsation for a compressor of a gaseous fluid, the apparatus comprising: a housing with an inlet opening and at least one first outlet opening, and a piston element which is movable in an axial direction within a volume enclosed by the housing and is arranged in a beared manner supported on the housing via a spring element, wherein a movement of the piston element respectively controls a flow cross section of the inlet opening and of the at least one first outlet opening, wherein the piston element and the housing each respectively have at least one first sealing surface and at least one second sealing surface, wherein the at least one first sealing surface forms a first seat and the at least one second sealing surface forms a second seat, and in that, between the first seat and the second seat respectively at least one chamber enclosed by the housing and the piston element for expanding the fluid when flowing into the chamber, and/or at least one second outlet opening in the housing is formed.

17. The apparatus according to claim 16, wherein the housing has a hollow cylindrical shape with an open first end face and a closed second end face distally arranged to the first end face, wherein the first end face of the housing is formed as an inlet opening for the fluid, wherein the at least one first outlet opening is formed on an outer surface and in a region of the second end face of the housing, wherein the at least one first sealing surface of the housing is formed such that it fully encloses the inlet opening, and wherein the at least one second sealing surface of the housing is formed at an inner wall and fully enclosing the inner wall and in a region of a side of the at least one first outlet opening oriented towards the inlet opening.

18. The apparatus according to claim 16, wherein the at least one second outlet opening is arranged adjacent to the at least one first sealing surface of the housing such that the at least one first sealing surface is arranged in a radial direction between the inlet opening and the at least one second outlet opening, wherein the at least one second outlet opening is formed as a straight flow channel with a small flow cross section and at least one change in direction.

19. The apparatus according to claim 16, wherein the piston element is formed from at least two sections which are arranged such that they are oriented towards one another on a common longitudinal axis in the axial direction.

20. The apparatus according to claim 19, wherein the piston element has a first section, a second section, and a third section, wherein the first section of the piston element is formed in a shape of a circular disc, and wherein the first section of the piston element is formed with a convexly curved free surface which is arranged oriented towards a direction of the inlet opening of the housing.

21. The apparatus according to claim 16, wherein the piston element has a first section and a second section, wherein the first section of the piston element is formed in a shape of a circular truncated cone or a hollow cylinder with a conical outer surface and a closed first end face.

22. The apparatus according to claim 21, wherein an outer diameter of the first section of the piston element is smaller than an inner diameter of the housing, such that an annular flow path for the fluid is formed between an inner wall of the housing and a circumferential surface of the first section of the piston element.

23. The apparatus according to claim 16, wherein the at least one first sealing surface of the piston element is formed at a surface of a first section of the piston element oriented towards a direction of the inlet opening of the housing or at a first end face of a second section of the piston element oriented towards the direction of the inlet opening of the housing.

24. The apparatus according to claim 23, wherein the at least one first sealing surface is formed such that it fully encloses the first section of the piston element in a region of the second end face.

25. The apparatus according to claim 16, wherein the at least one second sealing surface of the piston element is formed at an outer wall of a third section of the piston element or at an outer wall of a second section of the piston element.

26. The apparatus according to claim 16, wherein the piston element has a bypass opening which is formed extending from an end face oriented in a direction of the inlet opening of the housing in the axial direction through the piston element.

27. The apparatus according to claim 16, wherein the housing has a bypass opening which connects a volume formed at the inlet opening to a volume formed at the at least one second outlet opening (2-5).

28. The apparatus according to claim 1, characterized in that the spring element (4) is arranged concentrically within the piston element (3a, 3a′, 3b, 3b′, 3c, 3e) at least in regions depending on the deflection.

29. The apparatus according to claim 16, wherein the piston element is arranged in an end position in a minimal distance to the inlet opening of the housing such that the flow cross section of the inlet opening and/or of the at least one first outlet opening of the housing is/are closed.

30. The apparatus according to claim 16, wherein the piston element is arranged in an end position in a maximal distance to the inlet opening of the housing such that the flow cross section of the inlet opening and of the at least one first outlet opening are fully opened.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0062] Further details, features and advantages of designs of the invention result from the following description of example embodiments with reference to the associated drawings. The figures respectively show an apparatus for damping pressure pulsation for a compressor with a housing as well as a piston element which is arranged movably in an axial direction within a volume enclosed by the housing and spring-loaded in an axial longitudinal sectional view. It is shown:

[0063] FIGS. 1A and 1B: a first and a second embodiment with different design of the piston element,

[0064] FIG. 2A to 2C: the first embodiment of the apparatus of FIG. 1A in different operating states,

[0065] FIG. 3: a third embodiment with a housing with pre-outlets for the outflow of the fluid as well as a deviating design of the piston element in comparison to the above apparatus,

[0066] FIG. 4A to 4D: the third embodiment of the apparatus of FIG. 3 in different operating states and detail representations,

[0067] FIG. 5A to 5E: a fourth embodiment with a housing with pre-outlets for the outflow of the fluid and a piston element similar to the first embodiment according to FIG. 1A in a closed state, states respectively for the passage of a minimum mass flow with alternative embodiments of the piston element or of the housing as well as a state for the passage of a medium to large mass flow, and

[0068] FIG. 5F: the piston element of the fourth embodiment in a plan view and a perspective representation,

[0069] FIG. 6A to 6E: a fifth embodiment with a housing with pre-outlets for the outflow of the fluid and a piston element similar to the second embodiment according to FIG. 1B in a closed state, states respectively for the passage of a minimum mass flow with alternative embodiments of the piston element or of the housing as well as a state for the passage of a medium to large mass flow, and

[0070] FIG. 6F: the piston element of the fifth embodiment in a plan view and a perspective representation,

[0071] FIG. 7A to 7C: a sixth embodiment with a housing with pre-outlets for the outflow of the fluid and a deviating design of the piston element in a closed state in comparison to the above apparatus, a state for the passage of a low or minimum mass flow through an expansion chamber and exclusively through the pre-outlets and a state for the passage of a large mass flow, and

[0072] FIG. 7D: the piston element of the sixth embodiment in a plan view and a perspective representation.

DESCRIPTION OF AN EMBODIMENT

[0073] FIGS. 1A and 1B indicate a first embodiment and a second embodiment of an apparatus 1a, 1b for damping pressure pulsation for a compressor with a housing 2a as well as a piston element 3a, 3b which is arranged movably in an axial direction within a volume enclosed by the housing 2a and spring-loaded in an axial longitudinal sectional view.

[0074] The housing 2a formed for guiding the piston element 3a, 3b is fully arranged within a fluid channel of the fluid circuit, in particular of a refrigerant circuit, such that the fluid completely flows through the housing 2a. The housing 2a substantially has a hollow cylindrical, in particular a hollow circular cylindrical shape with an open first end face and a closed second end face arranged distally to the first end face. In doing so, the open first end face of the housing 2a is formed as an inlet opening 2-1. The outer surface of the hollow circular cylindrical housing 2a is provided with at least one outlet opening 2-2 in the region of the closed second end face.

[0075] The piston element 3a, 3b guided in the housing 2a has a first section 3a-1, 3b-1, a second section 3a-2, 3b-2 and a third section 3-3 which are arranged in the axial direction to one another. The sections 3a-1, 3b-1, 3a-2, 3b-2, 3-3 are arranged on a common longitudinal axis.

[0076] The first section 3a-1, 3b-1 is formed in the shape of a curved, cylindrical circular disc. A convexly curved free surface of the first section 3a-1, 3b-1 is oriented in the direction of the inlet opening 2-1 and thus to the open first end face of the housing 2a. The flow created by the fluid acts as a pressure force on the piston element 3a, 3b at the convexly curved first side of the first section 3a-1, 3b-1. The outer diameter of the circular disc can, on the one hand, according to the first embodiment of the apparatus 1a of FIG. 1A, be substantially less than the inner diameter of the hollow cylindrical housing 2a such that there is always a ring-shaped flow path for the fluid opened between the inner wall of the housing 2a and the circumferential surface of the circular disc. On the other hand, the outer diameter of the circular disc, according to the second embodiment of the apparatus 1b of FIG. 1B, can correspond to the inner diameter of the hollow circular cylindrical housing 2a minus only a gap for moving the piston element 3b within the housing 2a.

[0077] The circumferential surface of the circular disc of the first section 3a-1, 3b-1 of the piston element 3a, 3b has recesses, in particular in the shape of circular ring sections or wedge-shaped recesses, which extend from the circumferential surface in the direction of the axis of the circular disc. The recesses provide open flow paths for the fluid independent of the outer diameter of the circular disc.

[0078] The second section 3a-2, 3b-2 of the piston element 3a, 3b has a cylindrical, in particular a circular cylindrical shape. In doing so, the second section 3a-2, 3b-2 is connected to a second surface of the first section 3a-1, 3b-1 at a first end face of the cylinder. The second section 3a-2, 3b-2 has a smaller outer diameter than the first section 3a-1, 3b-1 of the piston element 3a, 3b. In doing so, the outer diameter of the second section 3a-2, 3b-2 can vary depending on the embodiment.

[0079] At a second end face which is formed distally to the first end face of the cylinder, the second section 3a-2, 3b-2 of the piston element 3a, 3b is connected to the third section 3-3 which substantially has a hollow cylindrical, in particular a hollow circular cylindrical shape with a closed first end face and an open second end face arranged distally to the first end face. The third section 3-3 of the piston element 3a, 3b is connected to the second section 3a-2, 3b-2 in the region of the closed first end face. The open second end face of the third section 3-3 of the piston element 3a, 3b is oriented towards the closed second end face of the housing 2a.

[0080] The outer diameter of the hollow circular cylindrical third section 3-3 corresponds to the inner diameter of the hollow circular cylindrical housing 2a minus a clearance for moving the piston element 3a, 3b within the housing 2a. Between the outer side of the outer surface of the third section 3-3 of the piston element 3a, 3b and the inner wall of the housing 2a, fluid-tight regions are formed which prevent a fluid mass flow, in particular a refrigerant mass flow, depending on the relative arrangement of the piston element 3a, 3b to the housing 2a.

[0081] The housing 2a has, at the open first end face, a first sealing surface 2-3 which fully encloses the inlet opening 2-1 and, at the inner wall, a second sealing surface 2-4 which fully encloses the inner wall. The second sealing surface 2-4 of the housing 2a is formed in a region of the sides of the outlet openings 2-2 oriented towards the inlet opening 2-1.

[0082] The piston element 3a, 3b has, at the convexly curved free surface of the first section 3a-1, 3b-1 oriented in the direction of the inlet opening 2-1 and thus to the open first end face of the housing 2a, a first sealing surface 3-4 which corresponds with the first sealing surface 2-3 of the housing 2a which fully encloses the inlet opening 2-1. Furthermore, the third section 3-3 of the piston element 3a, 3b is formed with a second sealing surface 3-5 which is provided at the outer wall of the hollow circular cylindrical section 3-3. The second sealing surface 3-5 is formed fully enclosing the outer wall of the third section 3-3 or at least respectively in a region of an outlet opening 2-2 of the housing 2a. The second sealing surface 3-5 of the piston element 3a, 3b respectively corresponds with the second sealing surface 2-4 of the housing 2a.

[0083] The piston element 3a, 3b, together with the housing 2a, forms throughflow openings 5 and at least one outflow opening 6 through which the fluid, in particular the refrigerant, can flow. The throughflow openings 5 are limited from the circumferential surface of the circular disc of the first section 3a-1, 3b-1 of the piston element 3a, 3b with the recesses and the inner wall of the housing 2a, while each outflow opening 6 represents a region of an outlet opening 2-2 of the housing 2a which is not covered by the piston element 3a, 3b. With the change of the axial position of the piston element 3a, 3b relative to the housing 2a, on the one hand, the size of the second sealing surface 2-4 of the housing 2a and the second sealing surface 3-5 of the piston element 3a, 3b which abut each other and correspond with each other, and on the other hand, the size of the flow cross sections at the inlet opening 2-1 and the outflow openings 6 can be varied.

[0084] The piston element 3a, 3b is moved by means of the flow force or pressure force of the fluid flowing through the inlet opening 2-1 into the housing 2a acting on the piston element 3a, 3b at the convexly curved first side of the first section 3a-1, 3b-1 and by a spring force acting on the piston element 3a, 3b in the opposite axial direction of the flow force of the fluid. Between the housing 2a and the piston element 3a, 3b, a spring element 4 is provided, which is arranged in a beared manner at a support 4-1 on the housing 2a on the one hand and at a support 4-2 on the piston element 3a, 3b on the other hand.

[0085] The spring element 4 formed as a coil spring, in particular a pressure spring, especially cylindrical, is arranged with the coil axis on the longitudinal axis of the housing 2a and the piston element 3a, 3b. In doing so, the spring element 4 abuts the support 4-1 of the housing 2a with a first end, while the second end of the spring element 4 abuts the support 4-2 of the piston element 3a, 3b. The spring element 4 is arranged concentrically to the longitudinal axis of the housing 2a via a centering aid in the region of the support 4-1.

[0086] The support 4-2 for the spring element 4 is provided at the closed first end face of the third section 3-3 of the piston element 3a, 3b such that the spring element 4 is fixed in a centered manner in the region of the second end within the volume enclosed by the hollow cylindrical third section 3-3. The spring element 4 protrudes through the open second end face into the volume enclosed by the third section 3-3 of the piston element 3a, 3b and is arranged concentrically within the piston element 3a, 3b at least in regions depending on the pressure forces acting on the piston element 3a, 3b.

[0087] The spring force of the spring element 4 acting as a pressure force constitutes a counter force to the flow force of the fluid acting as a pressure force. The respective pressure forces respectively act along the axial direction opposite to each other. The arrangement of the piston element 3a, 3b within the housing 2a for varying the sizes of the flow cross sections at the inlet opening 2-1 and the outflow openings 6 results from the spring constants of the spring element 4 depending on the flow force applied by the fluid.

[0088] The piston element 3a, 3b is guided at the sealing surfaces 2-3, 3-4, 2-4, 3-5 within the housing 2a corresponding with each other and designed as seats. In doing so, the first seat is formed with the first sealing surface 2-3 of the housing 2a and the first sealing surface 3-4 of the piston element 3a, 3b in the shape of a cone seat with the minimum throughflow openings 5 configured as recesses in the region of the circumferential surface of the circular disc of the first section 3a-1, 3b-1 of the piston element 3a, 3b. The second seat is formed with the second sealing surface 2-4 of the housing 2a and the second sealing surface 3-5 of the piston element 3a, 3b as a slider with several outflow openings 6 arranged in the radial direction in the housing 2a.

[0089] The mass flow of the fluid, in particular the refrigerant mass flow, is accelerated due to the respective cross sectional narrowing when flowing through the seats. In doing so, the first sealing surfaces 2-3, 3-4 and the second sealing surfaces 2-4, 3-5 are arranged spaced apart from each other in the flow direction of the fluid such that a chamber 7a, 7b of sufficient size for expanding and thus decelerating the mass flow is formed between the two seats.

[0090] The volumes of the chambers 7a, 7b of the apparatus 1a, 1b are limited by the inner side of the outer surface of the hollow circular cylindrical housing 2a, the second surface of the first section 3a-1, 3b-1 of the piston element 3a, 3b, the outer side of the second section 3a-2, 3b-2 of the piston element 3a, 3b and the first end face of the third section 3-3 of the piston elements 3a, 3b and differ in size. The different size of the chambers 7a, 7b is enabled, according to the embodiments of FIGS. 1A and 1B, in particular through the variation of the outer diameter of the second section 3a-2, 3b-2. Furthermore, the size of the chambers 7a, 7b can be changed via the length of the apparatus 1a, 1b for a given outer diameter of the housing 2a.

[0091] The piston element 3a, 3b is moved within the housing 2a depending on the mass flow of the fluid through the apparatus 1a, 1b in the axial direction and thus the flow cross sections on the seats or between the sealing surfaces 2-3, 3-4, 2-4, 3-5 are increased or reduced correspondingly in order to correspond to the respective mass flow. When passing the apparatus 1a, 1b, the mass flow is accelerated and expanded several times in succession. In doing so, the energy of the pressure pulses or of the pressure pulsation in the mass flow is converted into kinetic energy and back into pressure energy several times through the acceleration. This reduces the amplitudes of the impulses. The serial connection of the seats as bottlenecks and the expansion volumes cause an improved pulsation dampening with the same or lower pressure loss compared to the apparatus known from the state of the art.

[0092] FIG. 2A to 2C respectively show the first embodiment of the apparatus 1a of FIG. 1A in different operating states.

[0093] FIG. 2A reveals the apparatus 1a in a closed state and therefore without mass flow. The housing 2a and the piston element 3a form two closed seats with respective sealing surfaces 2-3, 3-4, 2-4, 3-5 which abut each other in a sealing manner. Both the first seat with the first sealing surfaces 2-3, 3-4 and the second seat with the second sealing surfaces 2-4, 3-5 are closed. The first sealing surface 3-4 of the piston element 3a formed at the first section 3a-1 is pressed against the first sealing surface 2-3 which fully encloses the inlet opening 2-1 of the housing 2a through the pressure force applied by the spring element 4.

[0094] FIG. 2B represents the apparatus 1a in a minimum opened state and thus a state with a low or minimum mass flow in the flow direction 8 of the fluid through the apparatus 1a.

[0095] With the movement of the piston element 3a in the axial direction caused by an increasing pressure force created by the flow of the fluid and acting on the piston element 3a, both the first sealing surfaces 2-3, 3-4 of the first seat and the second sealing surfaces 2-4, 3-5 of the second seat are moved away from each other, the seats are opened. The fluid flowing through the inlet opening 2-1 of the housing 2a into the apparatus 1a is guided through the throughflow openings 5 as opened first seats into the chamber 7a and expanded due to the large increase of the flow cross section. The fluid then flows out of the apparatus 1a through the outflow openings 6 as opened second seats under increasing pressure and is again expanded.

[0096] The opening of the throughflow openings 5 and of the outflow openings 6 can be simultaneously or sequentially, depending on the design of the apparatus 1a, in particular the dimensions of the housing 2a and the piston element 3a. Furthermore, the flow speed of the fluid can be varied with a different size of the volume of the chamber 7a, 7b of the apparatus 1a, 1b as part of the flow path of the fluid through the apparatus 1a, 1b.

[0097] FIG. 2C shows the apparatus 1a in a fully opened state with a maximum mass flow in the flow direction 8 of the fluid through the apparatus 1a. With the movement of the piston element 3a in the axial direction caused by a maximum pressure force created by the flow of the fluid and acting on the piston element 3a, both the first sealing surfaces 2-3, 3-4 of the first seat and the second sealing surfaces 2-4, 3-5 of the second seat are further moved away from each other, the seats are fully opened. The fluid flowing through the inlet opening 2-1 of the housing 2a into the apparatus 1a is guided out of the apparatus 1a through the fully opened outflow openings 6. As the outflow openings 6 are arranged distributed around the circumference of the apparatus 1a, the mass flow for an outflow opening 6 represented with the flow direction 8 is represented as an example. The chamber 7a is not formed.

[0098] According to an alternative embodiment which is not represented, the apparatus has more than two seats. Each region formed as a chamber or enlarged volume between the seats serves the expansion of the fluid. The seats are respectively configured to open a passage with a smaller flow cross section for the fluid such that the flow cross section for the fluid is reduced at least two times in the flow direction of the fluid and the fluid is expanded when flowing through the seats. The respective open flow cross section of each seat is varied with the stroke of the piston element and thus adapted to the throughflow.

[0099] The design of the ratios of the sealing surfaces of the seats and the expansion surfaces can change the function of compensation of pressure pulsation waves. The opening characteristics of the apparatus can be adapted via the design of the seats.

[0100] FIG. 3 shows a third embodiment of an apparatus 1c for damping pressure pulsation for a compressor with a housing 2c and a spring-loaded piston element 3c movably arranged in the axial direction within the volume enclosed by the housing 2c in an axial length cross sectional view.

[0101] The housing 2c formed for guiding the piston element 3c again is fully arranged within a fluid channel of the fluid circuit, in particular of a refrigerant circuit, such that the fluid completely flows through the housing 2c. The housing 2c substantially has, like in the first and the second embodiment according to FIGS. 1A and 1B, a hollow cylindrical, in particular a hollow circular cylindrical shape with an open first end face and a closed second end face arranged distally to the first end face. In doing so, the open first end face of the housing 2c is formed as an inlet opening 2-1. The outer surface of the hollow circular cylindrical housing 2c is provided with at least one first outlet opening 2-2 in the region of the closed second end face. The same elements of the apparatus 1a, 1b, 1c which are repeated in the different embodiments are characterized with same reference numerals.

[0102] A substantial difference compared to the apparatus 1a, 1b of the first and the second embodiment according to FIGS. 1A and 1B is in the form of the piston element 3c.

[0103] The piston element 3c guided in the housing 2c has a first section 3c-1 and a second section 3c-2 which are arranged towards one another on a common longitudinal axis in the axial direction.

[0104] The first section 3c-1 of the piston element 3c is formed in the shape of a circular truncated cone or a hollow cylinder, in particular a hollow circular cylinder, with a slightly conical outer surface and a closed first end face. The first end face at which the flow created by the fluid acts on the pressure element 3c as a pressure force is arranged in the direction of the inlet opening 2-1 and thus to the open first end face of the housing 2c.

[0105] The outer diameter of the first section 3c-1 of the piston element 3c is smaller than the inner diameter of the hollow circular cylindrical housing 2c such that there is always an annular flow path for the fluid opened between the inner wall of the housing 2c and the circumferential surface of the circular truncated cone. Furthermore, the outer diameter of the first section 3c-1 of the piston element 3c substantially corresponds to the inner diameter of the inlet opening 2-1. Due to the conical form of the first section 3c-1, the piston element 3c can be inserted into the inlet opening 2-1 with the first end face of the first section 3c-1 ahead and arranged centrally within the inlet opening 2-1.

[0106] The circumferential surface of the frustoconical first section 3c-1 of the piston element 3c has recesses, in particular in the shape of circular ring sections or wedge-shaped recesses, which extend from the circumferential surface in the direction of the longitudinal axis of the piston element 3c. The recesses can provide open flow paths for the fluid with an arrangement of the piston element 3c within the inlet opening 2-1 as well.

[0107] At a second end face which is formed distally to the first end face of the circular truncated cone, the first section 3c-1 of the piston element 3c is connected to the second section 3c-2 which substantially has a hollow cylindrical, in particular a hollow circular cylindrical shape with a first end face and an open second end face arranged distally to the first end face. The second section 3c-2 of the piston element 3c is connected to the first section 3c-1 in the region of the first end face. The open second end face of the second section 3c-2 of the piston element 3c is oriented towards the closed second end face of the housing 2c.

[0108] The outer diameter of the hollow circular cylindrical second section 3c-2 corresponds to the inner diameter of the hollow circular cylindrical housing 2c minus a clearance for moving the piston element 3c within the housing 2c. Between the outer side of the outer surface of the second section 3c-2 of the piston element 3c and the inner wall of the housing 2c, fluid-tight regions are formed which prevent a fluid mass flow, in particular a refrigerant mass flow, depending on the relative arrangement of the piston element 3c to the housing 2c.

[0109] The housing 2c of the third embodiment of the apparatus 1c of FIG. 3 also has the first sealing surface 2-3 which fully encloses the inlet opening 2-1 at the open first end face and the second sealing surface 2-4 which fully encloses the inner wall at the inner wall, which is formed in a region of the sides of the outlet openings 2-2 oriented towards the inlet opening 2-1.

[0110] The piston element 3c has, at the first end face of the second section 3c-2 oriented in the direction of the inlet opening 2-1 and thus to the open first end face of the housing 2c, a first sealing surface 3-4 which corresponds with the first sealing surface 2-3 of the housing 2c which fully encloses the inlet opening 2-1. In doing so, the first sealing surface 3-4 is formed such that it fully encloses the first section 3c-1 in the region of the second end face. Furthermore, the second section 3c-2 of the piston element 3c has a second sealing surface 3-5 which is provided at the outer wall of the hollow circular cylindrical second section 3c-2. The second sealing surface 3-5 is formed fully enclosing the outer wall of the second section 3c-2 or at least respectively in a region of an outlet opening 2-2 of the housing 2c. The second sealing surface 3-5 of the piston element 3c corresponds with the second sealing surface 2-4 of the housing 2c.

[0111] The piston element 3c together with the housing 2c forms at least one first outflow opening 6-1 through which the fluid, in particular the refrigerant flows. The first outflow opening 6-1 constitutes a region of an outlet opening 2-2 of the housing 2c which is not covered by the piston element 3c. With the change of the axial position of the piston element 3c relative to the housing 2c, on the one hand, the size of the second sealing surface 2-4 of the housing 2c and the second sealing surface 3-5 of the piston element 3c which abut each other and correspond with each other, and on the other hand, the size of the flow cross sections at the inlet opening 2-1 and the outflow openings 6-1 can be varied.

[0112] A further substantial difference compared to the apparatus 1a, 1b of the first and the second embodiment according to FIGS. 1A and 1B is in the form of the housing 2c with the arrangement of additional second outlet openings 2-5 for the fluid. The second outlet openings 2-5 which are respectively formed as a pre-outlet have the shape of a straight flow channel with a smaller flow cross section and are formed with a change in direction. Furthermore, several changes in direction of the flow within the flow channel can be guaranteed with flow directing baffles provided in the flow channel.

[0113] A pre-outlet 2-5 respectively extends from the region of the inlet opening 2-1 to the region of the outlet openings 2-2 of the housing 2c. In doing so, a respective first end of the pre-outlet 2-5 is arranged as a second outflow opening 6-2 adjacent to the first sealing surface 2-3 of the housing 2c which fully encloses the inlet opening 2-1 such that the second outflow openings 6-2 border the first sealing surface 2-3 as first ends of the pre-outlets 2-5 in the radial direction offset to the outside. The first sealing surface 2-3 of the housing 2c is formed in the radial direction between the inlet opening 2-1 and the second outflow openings 6-2.

[0114] In doing so, substantially two straight sections of a pre-outlet 2-5 are respectively oriented in parallel to the inlet opening 2-1 and connected to one another via a deflection section such that a mass flow of the fluid which is guided through the pre-outlet 2-5, after flowing through the inlet opening 2-1, experiences a first deflection and when flowing through the deflection section, experiences a second deflection of the flow direction of 180° in each case and flows out of the pre-outlet 2-5 through a second end in the region of the outlet openings 2-2.

[0115] The piston element 3c is moved by means of the flow force or pressure force of the fluid flowing through the inlet opening 2-1 into the housing 2c acting on the piston element 3c at the first end face of the first section 3c-1 and depending on the arrangement of the piston element 3c within the housing 2c also on the first sealing surface 3-4 and a spring force acting on the piston element 3c in the opposite axial direction of the flow force of the fluid. Between the housing 2c and the piston element 3c, a spring element 4 is provided, which is arranged in a beared manner at a support 4-1 on the housing 2c on the one hand and at a support 4-2 on the piston element 3c on the other hand.

[0116] The support 4-2 for the spring element 4 is formed at the first end face of the second section 3c-2 of the piston element 3c such that the spring element 4 is fixed in a centered manner within the volume enclosed by the hollow cylindrical second section 3c-2. The spring element 4 protrudes through the open second end face into the volume enclosed by the second section 3c-2 of the piston element 3c and is arranged concentrically within the piston element 3c at least in regions depending on the pressure forces acting on the piston element 3c.

[0117] The piston element 3c is moved within the housing 2c depending on the mass flow of the fluid through the apparatus 1c in the axial direction and thus the flow cross sections on the seats or between the sealing surfaces 2-3, 3-4, 2-4, 3-5 are increased or reduced correspondingly in order to correspond to the respective mass flow. The mass flow of the fluid can be guided through the apparatus 1c via different flow paths, wherein the respective flow path of the fluid depends on the position of the piston element 3c within the housing 2c or on the relative arrangement of the piston element 3c and the housing 2c with regard to each other.

[0118] FIG. 4A to 4D respectively show the third embodiment of the apparatus 1c of FIG. 3 in different operating states and detailed representations.

[0119] FIG. 4A shows the apparatus 1c in a closed state and therefore without mass flow. The housing 2c and the piston element 3c form two closed seats with respective sealing surfaces 2-3, 3-4, 2-4, 3-5 which abut each other in a sealing manner. Both the first seat with the first sealing surfaces 2-3, 3-4 and the second seat with the second sealing surfaces 2-4, 3-5 are closed. The first sealing surface 3-4 of the piston element 3c formed at the second section 3c-2 is pressed against the first sealing surface 2-3 which fully encloses the inlet opening 2-1 of the housing 2c through the pressure force applied by the spring element 4. The first section 3c-1 of the piston element 3c is arranged within the inlet opening 2-1.

[0120] FIG. 4B reveals the apparatus 1c in a state with closed first outflow openings 6-1 or closed first outlet openings 2-2 of the housing 2c and opened second outflow openings 6-2 or opened second outlet openings 2-5 of the housing 2c and thus a state with a low or minimum mass flow in the flow direction 8 of the fluid through the apparatus 1c in a detailed representation.

[0121] Through the movement of the piston element 2c in the axial direction caused by an increasing pressure force created by the flow of the fluid and acting on the piston element 3c, the first sealing surfaces 2-3, 3-4 of the first seat are moved away from each other, while the second sealing surfaces 2-4, 3-5 of the second seat still abut each other. At a low load, i.e. a low mass flow of the fluid, the piston element 3c, starting from the arrangement of the fully closed state of the apparatus 1c of FIG. 4A, only moves a short distance such that first only the second outlet openings 2-5 of the housing 2c configured as pre-outlets are opened. The outlet openings 2-5 are opened after a minimum stroke of the piston element 3c.

[0122] This means that the first seat is opened while the second seat remains closed. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1c is discharged from the apparatus 1c through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets.

[0123] In FIG. 4C, the apparatus 1c is shown in a state with opened first outflow openings 6-1 or opened first outlet openings 2-2 of the housing 2c as well as opened second outflow openings 6-2 or opened second outlet openings 2-5 of the housing 2c and thus a state with a large mass flow in the flow direction 8 of the fluid through the apparatus 1c in a detailed representation. Through the movement of the piston element 2c in the axial direction caused by a further increasing pressure force created by the flow of the fluid and acting on the piston element 3c, the first sealing surfaces 2-3, 3-4 of the first seat are moved further away from each other and the second sealing surfaces 2-4, 3-5 of the second seat are released from each other. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1c is divided into a first partial mass flow flowing out of the apparatus 1c through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets and a second partial mass flow flowing out of the apparatus 1c through the opened first outflow openings 6-1. The partial mass flows are mixed in the region of the first outlet openings 2-2 of the housing 2c when flowing out of the apparatus 1c.

[0124] FIG. 4D shows the apparatus 1c in a fully opened state with a maximum mass flow in the flow direction 8 of the fluid through the apparatus 1c. With the movement of the piston element 3c in the axial direction caused by a maximum pressure force created by the flow of the fluid and acting on the piston element 3c, both the first sealing surfaces 2-3, 3-4 of the first seat and the second sealing surfaces 2-4, 3-5 of the second seat are further moved away from each other, the seats are fully opened. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1c is substantially guided out of the apparatus 1c through the fully opened first outflow openings 6-1.

[0125] The third embodiment of the apparatus 1c with the second outlet openings 2-5 respectively formed as a pre-outlet or the second outflow openings 6-2 which open first during movement of the piston element 3c, while the first outflow openings 6-1 are still closed, are fully controllable in the size of the flow cross section, depending on the mass flow of the fluid flowing through the apparatus 1c, in particular in the case of very low mass flows. Also in the case of very low mass flows, the occurring pressure pulsation is reduced due to the flowing through the labyrinth-like pre-outlets 2-5. After a specific stroke of the piston element 3c, the first outlet openings 2-2, which are specially configured for the removal of the pressure pulsation, are opened as well as main outlet.

[0126] The apparatus 1c has an adapted throughflow characteristics for all different mass flows of the fluid. The outflow openings 6-1, 6-2 are adapted to one another such that the damping characteristics are optimal for every load situation.

[0127] FIG. 5A to 5E respectively show fourth embodiments and FIG. 6A to 6E respectively show fifth embodiments of an apparatus 1d, 1d′, 1d″ for damping pressure pulsation for a compressor with a housing 2c, 2c″ as well as a spring-loaded piston element 3a, 3a′, 3b, 3b′ movably arranged in the axial direction within the volume enclosed by the housing 2c, 2c″ in an axial longitudinal cross sectional representation. FIG. 5F shows a piston element 3a of a fourth embodiment and FIG. 6F shows a piston element 3b of a fifth embodiment respectively in a plan view and a perspective representation.

[0128] The apparatus 1d of a fourth embodiment according to FIGS. 5A, 5B and 5E is formed as a combination of the housing 2c of the third embodiment of the apparatus 1c according to FIGS. 3 and 4A to 4D and the piston element 3a of the first embodiment of the apparatus 1a according to FIG. 1A, while the apparatus 1d of a fifth embodiment according to FIGS. 6A, 6B and 6E represents a combination of the housing 2c of the third embodiment of the apparatus 1c according to FIGS. 3 and 4A to 4D and the piston element 3b similar to the second embodiment of the apparatus 1b according to FIG. 1B. The same elements of the apparatus 1a, 1b, 1c, 1d, 1d′, 1d″ which are repeated in the different embodiments are characterized with same reference numerals. Reference is made to the description of the individual components of the respective figures.

[0129] FIGS. 5A and 6A respectively represent the apparatus 1d in a closed state and therefore without mass flow. The housing 2c and the piston element 3a respectively form two closed seats with respective sealing surfaces 2-3, 3-4, 2-4, 3-5 which abut each other in a sealing manner. Both the first seat with the first sealing surfaces 2-3, 3-4 and the second seat with the second sealing surfaces 2-4, 3-5 are closed. The first sealing surface 3-4 of the piston element 3a, 3b formed at the first section 3a-1, 3b-1 is pressed against the first sealing surface 2-3 which fully encloses the inlet opening 2-1 of the housing 2c through the pressure force applied by the spring element 4. The first section 3a-1, 3b-1 of the piston element 3a, 3b is arranged such that it closes the inlet opening 2-1.

[0130] In FIGS. 5B and 6B, the apparatus 1d is respectively arranged in a state for guiding through a lower or minimum mass flow in the flow direction 8 of the fluid exclusively through the second outlet openings 2-5 formed as pre-outlets. In doing so, the first outflow openings 6-1 or the first outlet openings 2-2 of the housing 2c are closed, while the second outflow openings 6-2 or the second outlet openings 2-5 of the housing 2c are opened.

[0131] The first sealing surface 2-3 of the housing 2c and the first sealing surface 3-4 of the piston element 3a, 3b of the first seat are arranged spaced apart from each other such that the first seat is opened, while the second sealing surface 2-4 of the housing 2c and the second sealing surface 3-5 of the piston element 3a, 3b of the second seat abut each other such that the second seat is closed. Thus, the fluid only flows through the second outlet openings 2-5 of the housing 2c configured as pre-outlets which are released following a minimum stroke of the piston element 3a, 3b. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1d is discharged from the apparatus 1d through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets. The chamber 7a, 7b is not flown through by the fluid, but it serves as an expansion volume for the pressure pulses of the fluid which flows in and out through the throughflow openings 5 formed between the first section 3a 1, 3b-1 of the piston element 3a, 3b and the housing 2c.

[0132] FIGS. 5C and 6C respectively show an alternative embodiment of the piston element 3a′, 3b′ and thus of the fourth and fifth embodiment of the apparatus 1d′, while FIGS. 5D and 6D respectively show an alternative embodiment of the housing 2c″ and thus also of the fourth and fifth embodiment of the apparatus 1d“. In doing so, the apparatus 1d′, 1d” are respectively arranged in a closed state, but for guiding through a minimum mass flow.

[0133] The housing 2c, 2c″ and the piston element 3a, 3b, 3a′, 3b′ respectively form two closed seats with respective sealing surfaces 2-3, 3-4, 2-4, 3-5 which abut each other in a sealing manner. Both the first seat with the first sealing surfaces 2-3, 3-4 and the second seat with the second surfaces 2-4, 3-5 are closed.

[0134] In the case of the apparatus 1d′ according to FIGS. 5C and 6C, the piston element 3a′, 3b′ respectively has a bypass opening 3-6 for connecting a volume formed at the inlet opening 2-1 with a volume formed at an outlet opening, in particular the first outlet opening 2-2. The bypass opening 3-6 substantially extends in the axial direction through the piston element 3a′, 3b′, specially through the first section of the piston element 3a′, 3b′. When forming the piston element 3b′ with a hollow cylindrical second section 3b-2, the bypass opening 3-6 opens into the second volume enclosed by the second section 3b-2 of the piston element 3b′, which on the other hand is connected to a volume enclosed by the hollow cylindrical third section 3-3 of the piston element 3b′.

[0135] In doing so, the piston element 3a′, 3b′ has, in the axial direction, such a length that the first outlet opening 2-2 of the housing 2c with a closed second seat and thus abutting second sealing surfaces 2-4, 3-5 of the housing 2c and the piston element 3a′, 3b′ is not fully closed by the piston element 3a′, 3b′. A gap which provides a connection to the outlet opening 2-2 is opened to the housing 2c at an end face of the third section 3-3 of the piston element 3a′, 3b′ at a distal end oriented to the closed second seat in the axial direction.

[0136] The fluid flowing through the inlet opening 2-1 of the housing 2c in the flow direction 8 into the apparatus 1d′ is discharged from the apparatus 1d′ through the bypass opening 3-6 formed in the piston element 3a′, 3b′ and the gap formed between the piston element 3a′, 3b′ and the housing 2c as an opened first outlet opening 2-2.

[0137] In the case of the apparatus 1d″ according to FIGS. 5D and 6D, the housing 2c″ respectively has a bypass opening 2-6 for connecting a volume formed at the inlet opening 2-1 with a volume formed at an outlet opening, in particular the second outlet opening 2-5.

[0138] The fluid flowing through the inlet opening 2-1 of the housing 2c″ into the apparatus 1d″ is discharged from the apparatus 1d″ through the bypass opening 2-6 formed in the housing 2c″ and the opened second outflow openings 2-5.

[0139] In FIGS. 5E and 6E, the apparatus 1d is respectively arranged in a state for guiding through a medium to larger mass flow in the flow direction 8 of the fluid both through the second outlet openings 2-5 formed as pre-outlets and through the chamber 7a, 7b. Apart from the second outflow openings 6-2 or the second outlet openings 2-5 of the housing 2c, the first outflow openings 6-1 or the first outlet openings 2-2 of the housing 2c are opened as well.

[0140] Both the first sealing surface 2-3 of the housing 2c and the first sealing surface 3-4 of the piston element 3a, 3b of the first seat and the second sealing surface 2-4 of the housing 2c and the second sealing surface 3-5 of the piston element 3a, 3b of the second are arranged spaced apart from each other, the seats are opened. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1d is divided into a first partial mass flow flowing out of the apparatus 1d through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets and a second partial mass flow flowing out of the apparatus 1d through the opened first outflow openings 6-1. In doing so, the second partial mass flow of the fluid is guided into the chamber 7a, 7b through the throughflow openings 5 formed between the first section 3a-1, 3b-1 of the piston element 3a, 3b and the housing 2c and expanded due to the large increase of the flow cross section. The fluid then flows out of the apparatus 1d through the first outflow openings 6-1 as opened second seats under increasing pressure and is again expanded.

[0141] The substantial difference of the piston elements 3a of the apparatus 1a, 1d according to FIG. 1A as well as 5A, 5B and 5E is in the form of the first section 3a-1. While the outer diameter of the first section 3a-1 of the piston element 3a, formed as a circular disc, of the first embodiment of the apparatus 1a of FIG. 1A is substantially smaller than the inner diameter of the hollow circular cylindrical housing 2c, the outer diameter of the first section 3a-1 of the piston element 3a formed as a circular disc of the fifth embodiment of the apparatus 1d of FIGS. 5A, 5B and 5E corresponds to the inner diameter of the hollow circular cylindrical housing 2c minus only a gap for moving the piston element 3a within the housing 2c.

[0142] FIGS. 5F and 6F in particular show the formation of the recesses at the circumferential surface of the first section 3a-1, 3b-1 of the piston element 3a, 3b formed as a circular disc. The recesses which respectively provide open flow paths for the fluid respectively have the shape of a circular ring section. In doing so, adjacently arranged circular ring sections are separated from each other by webs. The webs extend in the radial direction to the outside to the maximum outer diameter of the first section 3a-1, 3b-1 of the piston element 3a, 3b. The four webs which are uniformly distributed about the circumference of the circumferential surface thus divide a circular ring formed between the wall at the inner diameter of the hollow circular cylindrical housing 2c and the circumferential surface of the first section 3a-1, 3b-1 of the piston element 3a, 3b into four equal circular ring sections with equal flow cross sections.

[0143] FIG. 7A to 7C respectively reveal a sixth embodiment of an apparatus 1e for damping pressure pulsation for a compressor with a housing 2c with pre-outlets for the outflow of the fluid as well as a spring-loaded piston element 3e formed in a deviating manner from the above apparatus 1a, 1b, 1c, 1d, 1d′, 1d″ movably arranged in the axial direction within the volume enclosed by the housing 2c in an axial longitudinal cross sectional representation.

[0144] The apparatus 1e of the sixth embodiment according to FIG. 7A to 7C is formed as a combination of the housing 2c of the third embodiment of the apparatus 1c according to FIGS. 3 and 4A to 4D and a combination of the piston element 3a of the first embodiment of the apparatus 1a according to FIG. 1A and the piston element 3b of the second embodiment of the apparatus 1b according to FIG. 1B. The same elements of the apparatus 1a, 1b, 1c, 1d, 1d′, 1d″, 1e which are repeated in the different embodiments are characterized with same reference numerals. Reference is made to the description of the individual components of the respective figures.

[0145] The substantial difference of the apparatus 1e according to FIG. 7A to 7C to the apparatus 1d according to FIGS. 5A, 5B and 5E as well as 6A, 6B and 6E is in the form of the housing 2c and the piston element 3a, 3b, 3e, in particular in their correspondence behavior during states for guiding through a smaller or minimum mass flow.

[0146] The outer diameter of the first section 3e-1 of the piston element 3e of the sixth embodiment of the apparatus 1e formed as a circular disc is substantially smaller than the inner diameter of the hollow circular cylindrical housing 2c and therefore corresponds to the form of the first section 3a-1 of the piston element 3a of the first embodiment of the apparatus 1a according to FIG. 1A. The outer diameter of the second section 3e-2 of the piston element 3e of the sixth embodiment of the apparatus 1e formed as a cylinder, in particular as a circular cylinder, substantially corresponds to the outer diameter of the second section 3b-2 of the piston element 3b of the second and the fifth embodiment of the apparatus 1b, 1d according to FIG. 1B or 6A, 6B and 6E.

[0147] FIG. 7A shows the apparatus 1e in a closed state, while the apparatus 1e in FIG. 7B is shown in a state for guiding a smaller or minimal mass flow in the flow direction 8 of the fluid through a chamber 7e and then through the second outlet openings 2-5 formed as pre-outlets. The first outflow openings 6-1 or the first outlet openings 2-2 of the housing 2c are respectively closed, while the second outflow openings 6-2 or the second outlet openings 2-5 of the housing 2c are closed in the closed state of the apparatus 1e of FIG. 7A and opened in the state of FIG. 7B and connected to the chamber 7e.

[0148] In the state for guiding through a lower or minimum mass flow of FIG. 7B, the first sealing surface 2-3 of the housing 2c and the first sealing surface 3-4 of the piston element 3b of the first seat are either spaced apart from each other forming a minimum gap or are at least arranged with regard to one another such that the throughflow openings 5 formed by the first section 3e-1 of the piston element 3e together with the housing 2c are at least partially opened such that the first seat is opened as well. Furthermore, the second sealing surface 2-4 of the housing 2c and the second sealing surface 3-5 of the piston element 3e of the second seat abut one another such that the second seat is closed. Thus, the fluid can only flow through the second outlet openings 2-5 of the housing 2c configured as pre-outlets and connected to the chamber 7e. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1e is guided into the chamber 7e through the throughflow openings 5 formed between the first section 3e-1 of the piston element 3e and the housing 2c and expanded due to the large increase of the flow cross section. The fluid then flows out of the apparatus 1e through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets.

[0149] Through the movement of the piston element 2c in the axial direction caused by the pressure force created by the flow of the fluid and acting on the piston element 3e first sealing surfaces 2-3, 3-4 of the first seat can be moved further away from each other and the second sealing surfaces 2-4, 3-5 of the second seat can be released from each other. The fluid flowing through the inlet opening 2-1 of the housing 2c into the apparatus 1e is then divided into a first partial mass flow flowing out of the apparatus 1e through the opened second outflow openings 6-2 and the second outlet openings 2-5 of the housing 2c serving as pre-outlets and a second partial mass flow flowing out of the apparatus 1e through the opened first outflow openings 6-1.

[0150] FIG. 7C shows the apparatus 1e in a state for guiding through a medium to large mass flow in the flow direction 8 of the fluid both through the second outlet openings 2-5 formed as pre-outlets and through the chamber 7e, similar to the state of the fourth or fifth embodiment of the apparatus 1d of FIGS. 5E and 6E. Apart from the second outflow openings 6-2 or the second outlet openings 2-5 of the housing 2c, the first outflow openings 6-1 or the first outlet openings 2-2 of the housing 2c are opened as well. Reference is made to the representation of FIGS. 5E and 6E for further explanations.

[0151] As the outflow openings 6-1, 6-2 are arranged distributed around the circumference of the apparatus 1e, the mass flow for a respective outflow opening 6-1, 6-2 respectively represented with the flow direction 8 is represented as an example.

[0152] FIG. 7D reveals the piston element 3e of the sixth embodiment of the apparatus 1e in a plan view and a perspective representation. The recesses provided at the circumferential surface of the first section 3e-1 of the piston element 3e and providing open flow paths for the fluid, on the other hand, respectively have the form of a circular ring section. The circular cylindrical first section 3e-1 and the circular cylindrical second section 3e-2 of the piston element 3e are formed with outer diameters of equal size.

[0153] The webs separating the adjacently arranged circular ring sections from each other respectively extend from the outer diameter of the circular cylindrical first section 3e-1 in the radial direction to the outside.

[0154] The through openings formed as bypass openings 2-6 in the housing 2c″ or as bypass openings 3-6 in the piston element 3a′, 3b′ are to be regarded as alternative designs of the housing 2a, 2c, 2c″ and of the piston element 3a, 3a′, 3b, 3b′, 3c, 3e irrespective of the embodiment of the apparatus 1a, 1b, 1c, 1d, 1d′, 1d“, 1e. A combination of the different housings 2a, 2c, 2c” and piston elements 3a, 3a′, 3b, 3b′, 3c, 3e in an apparatus is possible as well.

[0155] Similarly, the second outlet openings 2-5 formed as pre-outlets can either be configured, as represented in the housing 2c, 2c″ of the apparatus 1c, 1d, 1d′, 1d“, 1e or in a wall of a component enclosing the housing 2c, 2c”, for example of the refrigerant circuit, in particular of the compressor or of a connection line, independent of the embodiment of the apparatus 1c, 1d, 1d′, 1d″, 1e.

[0156] With the apparatus 1c, 1d, 1d′, 1d″, 1e of FIGS. 3 to 7D, respectively with the housing 2c, 2c″ with pre-outlets, an optimum damping effect is achieved on the one hand and at the same time an excessive pressure loss is avoided.

LIST OF REFERENCE NUMERALS

[0157] 1a, 1b, 1c, 1d, 1d′, 1d“, 1e apparatus [0158] 2a, 2c, 2c” housing [0159] 2-1 inlet opening [0160] 2-2 (first) outlet opening [0161] 2-3 first sealing surface of the housing 2a, 2c, 2c″ [0162] 2-4 second sealing surface of the housing 2a, 2c, 2c″ [0163] 2-5 second outlet opening, pre-outlet [0164] 2-6 bypass opening of the housing 2c″ [0165] 3a, 3a.′, 3b, 3b′, 3c, 3e piston element [0166] 3a-1, 3b-1, 3c-1, 3e-1 first section of the piston element 3a, 3a.′, 3b, 3b′ 3c, 3e [0167] 3a-2, 3b-2, 3c-2, 3e-2 second section of the piston element 3a, 3a.′, 3b, 3b′, 3c, 3e [0168] 3-3 third section of the piston element 3a, 3a.′, 3b, 3b′, 3e [0169] 3-4 first sealing surface of the piston element 3a, 3a.′, 3b, 3b′, 3c, 3e [0170] 3-5 second sealing surface of the piston element 3a, 3a.′, 3b, 3b′, 3c, 3e [0171] 3-6 bypass opening of the piston element 3a.′, 3b′ [0172] 4 spring element [0173] 4-1 support of the housing 2a, 2c, 2c″ [0174] 4-2 support of the piston element 3a, 3a.′, 3b, 3b′, 3c, 3e [0175] 5 throughflow opening [0176] 6, 6-1 (first) outflow opening [0177] 6-2 second outflow opening [0178] 7a, 7b, 7e chamber [0179] 8 flow direction of the fluid