CYLINDER HEAD COVER FOR A REFRIGERANT COMPRESSOR

Abstract

Cylinder head cover (8) for a coolant compressor, wherein the cylinder head cover (8) is attachable to the cylinder head arrangement (21) in order to form a hollow space for receiving a coolant compressed by the piston, wherein the cylinder head arrangement (21) comprises a valve plate (9) attached to the cylinder housing and having an outlet opening (11) and an outlet valve (6,7), which closes the outlet opening (11) in cycles and consists of a valve spring (10) and a stop plate (6a,7a) for delimiting an opening movement of the valve spring (10).

In order to achieve a cost-efficient production and installation of the cylinder head cover (8) while assuring a secure support of the stop plate (6a,7a), it is provided according to the invention that the cylinder head cover (8) comprises at least two contact surfaces (12,13) for supporting stop plates (6a,7a) of different outlet valves (6,7) in order to adjust different opening positions of the valve springs (10) of the different outlet valves (6,7).

Claims

1. A cylinder head cover for a coolant compressor comprising an electric drive unit, a cylinder housing with a cylinder head arrangement, a crankshaft drivable by the electric drive unit, and a piston driven by the crankshaft, guided in the cylinder housing and compressing the coolant, wherein the cylinder head cover is attachable to the cylinder head arrangement in order to form a hollow space for receiving a coolant compressed by the piston, wherein the cylinder head arrangement comprises a valve plate attached to the cylinder housing with an outlet opening and an outlet valve, which closes the outlet opening in cycles and comprises a valve spring and a stop plate for delimiting an opening movement of the valve spring, wherein the cylinder head cover comprises at least two contact surfaces for supporting the stop plates of different outlet valves in order to allow for different opening positions of the valve springs of the different outlet valves.

2. The cylinder head cover according to claim 1, wherein the cylinder head cover has a support element which forms the contact surfaces, and two adjacent contact surfaces are formed by one recess of the support element.

3. The cylinder head cover according to claim 1, wherein the cylinder head cover comprises a continuous sealing surface for sealing the hollow space delimited by the valve plate, and that the contact surfaces are arranged at a varying standard distance (N.sub.1,N.sub.2) from the sealing surface.

4. The cylinder head cover according to claim 3, wherein the height difference between the contact surface arranged closest to the sealing surface and the contact surface arranged furthest from the sealing surface lies in a range between 0.2 mm and 2.6 mm.

5. The cylinder head cover according to claim 3, wherein the height difference between two adjacent contact surfaces lies between 0.2 mm and 2 mm.

6. The cylinder head cover according to claim 1, wherein the contact surfaces are designed to be curved to the shape of the stop plates of different outlet valves.

7. The cylinder head cover according to claim 1, wherein the contact surfaces are aligned parallel to one another.

8. The cylinder head cover according to claim 2, wherein the support element comprises a first and a second contact surface, wherein the first contact surface designed to support the stop plate of a first outlet valve in order to adjust a first opening position of the valve spring of the first outlet valve, and wherein the second contact surface is designed to support the stop plate of an alternative outlet valve in order to adjust an alternative opening position of the valve spring of the alternative outlet valve.

9. A coolant compressor having an electric drive unit, a cylinder housing, a crankshaft drivable by the electric drive unit, and a piston driven by the crankshaft, guided in the cylinder housing and compressing the coolant, wherein a cylinder head arrangement with a valve plate, which comprises an outlet opening, and an outlet valve is fastened to the cylinder housing, wherein the outlet valve comprises a valve spring, which closes the outlet opening in cycles, and a stop plate arranged on the valve plate for delimiting the opening movement of the valve spring, and a cylinder head cover, which supports the stop plate, is fastened to the cylinder head arrangement, wherein the cylinder head cover is designed according to claim 1.

10. The coolant compressor according to claim 9, wherein the stop plate comprises a fastening section attached to the valve plate and a free section for delimiting the opening movement of the valve spring, wherein an end portion of the free section bears against one of the contact surfaces.

11. The coolant compressor according to claim 10, wherein the stop plate is pre-stressed between the corresponding contact surface and the valve plate.

12. The coolant compressor according to claim 10, wherein the contact surface with the shortest distance from the longitudinal axis of the outlet opening in radial direction is arranged at a first standard distance (N.sub.1) from the valve plate, and the standard distances (N.sub.2) of the remaining contact surfaces are reduced from contact surface to contact surface, the farther away they are from the longitudinal axis.

13. The coolant compressor according to claim 9, wherein the contact surfaces are arranged relative to the valve plate, such that an opening height (H.sub.1,H.sub.2) of the valve spring in the opening position defined by the corresponding contact surface lies between 0.8 mm and 3.0 mm, wherein the opening height (H.sub.1,H.sub.2) of the valve spring is defined as the maximum distance between the valve plate and the valve spring, measured along a longitudinal axis of the outlet opening.

14. A compressor family with coolant compressors having a different cooling capacity due to different displacements wherein, depending on the displacement of the piston, a different outlet valve is attached to the valve plate, wherein a cylinder head cover according to claim 1 supports the stop plate of the outlet valve on one of the contact surfaces, and so structurally identical cylinder head covers can be used for the entire compressor family.

15. The compressor family according to claim 14, wherein the lengths of the free sections of the stop plates of the different outlet valves differ from one another.

16. The cylinder head cover of claim 2 wherein the recess of the support element is stepped.

17. The cylinder head cover of claim 4 wherein the range is between 0.4 mm and 2.0 mm.

18. The cylinder head cover of claim 4 wherein the range is between 0.6 mm and 1.6 mm.

19. The cylinder head cover of claim 4 wherein the range is between 0.8 mm and 1.2 mm.

20. The cylinder head cover of claim 5 wherein the height difference is between 0.4 and 1.6 mm.

21. The cylinder head cover of claim 5 wherein the height difference is between 0.8 and 1 mm.

22. The cylinder head cover of claim 6 wherein the contact surfaces are further designed to be adjusted to the shape of the stop plates of different outlet valves.

23. The cylinder head cover of claim 7 wherein the contact surfaces are parallel to the sealing surface.

24. The coolant compressor of claim 10 wherein the free section is curved.

25. The coolant compressor of claim 13 wherein the contact surfaces are arranged relative to the valve plate at different standard distances (N.sub.1,N.sub.2).

26. The coolant compressor of claim 13 wherein the opening height is between 1.0 mm and 2.8 mm.

27. The coolant compressor of claim 13 wherein the opening height is between 1.2 mm and 2.6 mm.

28. The coolant compressor of claim 13 wherein the opening height is between 1.6 mm and 1.8 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the following, the invention shall be described in more detail using embodiments. The drawings are exemplary and supposed to demonstrate the inventive idea but not limit it or even describe it exhaustively.

[0030] FIG. 1 shows a cutaway view of a coolant compressor;

[0031] FIG. 2a shows a cutaway view of the cylinder head cover according to the invention with a first outlet valve and an open valve spring;

[0032] FIG. 2b shows the cylinder head cover according to FIG. 2a with a closed valve spring;

[0033] FIG. 3a shows a cutaway view of the cylinder head cover with a second outlet valve and a closed valve spring;

[0034] FIG. 3b shows the cylinder head cover according to FIG. 3a with an open valve spring;

[0035] FIG. 4 shows an axonometric drawing of a cylinder head cover according to the invention;

[0036] FIG. 5 shows a cutaway view of the cylinder head cover without an outlet valve;

[0037] FIG. 6 shows a detailed depiction from FIG. 2b.

MEANS FOR EXECUTING THE INVENTION

[0038] FIG. 1 shows a cutaway view of a coolant compressor according to the invention, wherein the individual components are arranged within a, preferably hermetically encapsulated, compressor housing 1. The coolant compressor comprises an electric drive unit 2, which is designed as an electric motor with a rotor and a stator, a crankshaft 5, which is drivable by means of the drive unit 2, and a cylinder housing 3, in which a piston 4 is translationally movable and driven by the crankshaft 5. In a generally known manner, during the suction stroke, coolant is suctioned via a suction silencer 20 and a suction valve into the cylinder of the cylinder housing 3 or the compression space and compressed to a higher pressure level during the subsequent compression stroke. At the end of the compression stroke, the coolant compressed by the piston movement is ejected via an outlet valve 6,7 and transferred to a pressure section.

[0039] In order to ensure the functionality, a cylinder head arrangement 21 is provided which comprises a valve plate 9, by means of which the cylinder is closed. The valve plate 9 comprises a suction opening, which can be closed in cycles by the suction valve, and an outlet opening 11, which can be closed in cycles by the outlet valve 6,7, and by means of which the coolant reaches or leaves the cylinder. The valve plate 9 is clamped by a cylinder head cover 8 to the cylinder housing 3, wherein sealing elements 15, for example, flat seals made of plastic or paper, are usually arranged between the valve plate 9 and the cylinder head cover 8 or between the valve plate 9 and cylinder housing 3. The cylinder head cover 8, together with the valve plate 9, forms a hollow space, which the compressed coolant enters from the compression space via the outlet valve 6,7.

[0040] As a rule, coolant compressors are manufactured as part of a compressor family, wherein the individual coolant compressor types differ with regard to their cooling capacity. The different cooling capacities can be adjusted by a different dimensioning of the drive unit 2 and/or by displacements of different sizes. However, within the compressor family, the usual structural measures vary only slightly. Due to the different cooling capacity, the mass flows of the coolant which enter the hollow space formed by the cylinder head cover 8 via the outlet valve 6,7 during the exhaust stroke also differ. Therefore, the outlet valves 6,7 must be designed differently in different coolant compressor types of a compressor family.

[0041] As shown in FIGS. 2 and 3 using the invention, an outlet valve 6,7 comprises a valve plate 10 and a stop plate 6a,7a for the valve spring 10, wherein the stop plate 6a,7a delimits the opening movement of the valve spring 10, thus defining an opening movement of the valve spring 10. During the compression stroke, the dynamic pressure on the valve spring 10 increases, until the valve spring 10 opens. At a defined dynamic pressure, which is reached in a defined crank angle range, this results in an opening of the valve spring 10, which is accelerated during the opening. In order to prevent an overload of the valve spring 10, the stop plate 6a,7a for delimiting the opening movement of the valve spring 10 is provided. In the opening position, the valve spring 10, at least in the area of the projection of the outlet opening 11 on the stop plate 6a,7a, bears against the stop plate 6a,7a with its entire surface and cannot be opened any further. Similar to the valve spring 10, the stop plate 6a,7a is attached, preferably riveted, to the valve plate 9. According to the prior art, the stop plate 6a,7a is supported by the inner side of the cylinder head cover 8. However, in the prior art, this results in the following disadvantages: Since the stop plates 6a,7a of different outlet valves 6,7, determine the corresponding different opening positions of the valve springs 10, and require a counterpart for support in the cylinder head cover 8, the cylinder head cover 8 must be adjusted precisely to the corresponding outlet valve 6,7 in order to be able to support the stop plate 6a,7a in the right position. It thus requires a concrete combination of an outlet valve 6,7 and a cylinder head cover 8 adjusted to the outlet valve 6,7, which entails a great number of different combinations. This is associated with high production costs for the adjusted cylinder head covers 8 and high installation costs because prior to the execution of the installation steps, it must be verified whether the cylinder head cover 8 suitable for the outlet valve 6,7 is used.

[0042] FIGS. 2a and 2b show a cross-section of the cylinder head arrangement 21 with a first outlet valve 6 and the cylinder head cover 8 according to the invention; FIGS. 3a and 3b show a cross-section of the cylinder head arrangement 21 with a second outlet valve 7 and the cylinder head cover 8 according to the invention. As can be clearly seen, when comparing FIGS. 2 and 3, the above described disadvantages of the prior art are overcome in that the cylinder head cover 8 has a plurality of contact surfaces 12,13, which are each provided for a different outlet valve 6,7.

[0043] In the depicted embodiment, the cylinder head cover 8 has two contact surfaces 12,13 for the stop plates 6a,7a of two different outlet valves 6,7. In alternative embodiments, more than two contact surfaces, for example, three, four, or five contact surfaces, can be provided. Since the first contact surface 12 is designed for contacting the first stop plate 6a of the first outlet valve 6, and the second contact surface 13 is designed for contacting the second stop plate 7a of the second outlet valve 7, two different outlet valves 6,7 can be positioned in the cylinder head arrangement 21 with structurally identical cylinder head covers 8. In other words, the cylinder head cover 8 can be used in different coolant compressors or coolant compressor types, which each require different opening positions of the valve spring 10 and thus have different outlet valves 6,7.

[0044] The contact surfaces 12,13 are naturally arranged in the internal space of the cylinder head cover 8, which forms the hollow space, and face the valve plate 9. In the present embodiment, the cylinder head cover 8 has a support element 14 which forms the contact surfaces 12,13. The cylinder head cover 8, together with the support element 14, is designed as a single-piece cast part, wherein the support element 14 protrudes from the cover surface of the cylinder head cover 8 in the direction of the valve plate 9. On the side facing the valve plate 9, the cylinder head cover 8 has a continuous sealing surface 16 in order to seal the formed hollow space by means of the sealing element 15 which is arranged between the cylinder head cover 8 and the valve plate 9. As can be seen in FIG. 4, the basically flat sealing surface 16 has a continuous bulge 24 which increases the surface pressure on the sealing element 15, thus securing the sealing element 15 between cylinder head cover 8 and valve plate 9 and preventing the sealing element 15 from being pushed out during operation.

[0045] The two contact surfaces 12,13 are formed by a stepped recess of the support element 14, wherein the contact surfaces 12,13 are aligned parallel to the valve plate 9 or parallel to the sealing surface 16. In alternative embodiments, it can also be provided that the contact surfaces 12,13 are aligned parallel to one another, but run obliquely with regard to the sealing surface 16, or that the contact surfaces 12,13 are designed to be curved, for example, to correspond to the shape of the stop plates 6a,7a. The described possibilities for the arrangement and design of the first and second contact surface 12,13 can be applied to any number of contact surfaces.

[0046] FIGS. 2a and 3a clearly show that the stop plates 6a,7a of the outlet valves 6,7 are designed differently, while the valve springs 10 are designed to be structurally identical. It goes without saying that the outlet valves 6,7 can also have differently designed valve springs 10. The two outlet valves 6,7 are in a closed position, in which the outlet opening 11 is closed by the valve spring 10. As a rule, the outlet valves 6,7 assume this position during the suction stroke and during compression, before the valve springs 10 yield to the dynamic pressure and assume the opening position.

[0047] In order to clarify the arrangement of the contact surfaces 12,13, FIG. 5 shows the cylinder head cover 8, which is fastened to the valve plate 9, without an outlet valve 6,7. It can be clearly seen that the first contact surface 12 is arranged at a first standard distance N.sub.1, and the second contact surface 13 is arranged at a second standard distance N.sub.2 to the valve plate 9 or the sealing surface 16. The first contact surface 12 is arranged closer to the longitudinal axis 22 of the outlet opening 11, i.e., it has a shorter distance to the longitudinal axis 22 in radial direction (with regard to the longitudinal axis 22). The first standard distance N.sub.1 is also greater than the second standard distance N.sub.2, and so, with regard to the valve plate 9, the first contact surface 12 lies higher up than the second contact surface 12. In the present embodiment, the first standard distance N.sub.1 of the first contact surface 12 is 6.1 mm, while the second standard distance N.sub.2 of the second contact surface 13 is 5.2 mm. If a third and fourth contact surface were provided, the third contact surface would have a shorter standard distance than the second contact surface, and the fourth contact surface would have a shorter standard distance than the third contact surface, and so the contact surface with the greatest radial distance to the longitudinal axis 22 has the shortest standard distance to the valve plate 9.

[0048] These different standard distances N.sub.1,N.sub.2 ensure that the first stop plate 6a bearing against the first contact surface 12 (FIGS. 2a and 2b) allows for a greater opening of the valve spring 10 (FIG. 2b) than the second stop plate 7a bearing against the second contact surface 13 (FIG. 3b), wherein the two stop plates 6a,7a have essentially the same thickness. In other words, with the design according to the invention of the two contact surfaces 12,13, it is possible in a simple manner to adjust different opening positions of the valve spring 10, depending on whether a stop plate 6a is provided for the first contact surface 12, or whether a stop plate 7a is provided for the second contact surface 13. A comparison of FIGS. 2b and 3b shows particularly clearly the two different opening positions of the valve springs 10 of the two different outlet valves 6,7, wherein the valve spring 10 of the first outlet valve 6 is open wider in its opening position than the valve spring 10 of the second outlet valve 7.

[0049] In order to clarify this substantive matter, FIG. 6 shows a detailed view of the first outlet valve 6 in the open position (see FIG. 2b), wherein particularly the area around the outlet opening 11 in the valve plate 9 is shown. The first stop plate 6a is supported by the first contact surface 12 of the cylinder head cover 8. A first opening height of the first valve spring 10, measured along the longitudinal axis 22 as the distance between the upper side of the valve plate 9 and the underside of the valve spring 10 which bears against the first stop plate 6a, is indicated. In the present embodiment, the opening height H.sub.1 is 2.6 mm, while the second opening height H.sub.2 of the second outlet valve 7 (not depicted) is determined analogously and in the present embodiment is 1.6 mm. Conceivable values for the opening height H of the valve spring for coolant compressors with a displacement between 15 cm.sup.3 and 21 cm.sup.3 are 1.0 mm, 1.2 mm, 1.6 mm, 1.8 mm, 2.6 mm, and 2.8 mm. It goes without saying that each of the contact surfaces 12,13 defines an opening height H of a valve spring 10 of an outlet valve, and any combination of different opening heights H is conceivable. For coolant compressors with a smaller or larger displacement, values deviating from the values indicated above can also be provided for the opening height H.

[0050] It is also clearly shown that in the opening position, the valve springs 10 of both outlet valves 6,7 bear against the corresponding stop plate 6a,7a with their entire surface, and the stop plates 6a,7a are curved such that they correspond to the bending line of the valve springs 10. The stop plates 6a,7a each comprise a fastening section 17, by means of which the stop plates 6a,7a are fastened to the valve plate 9, and a free section 18, wherein the free section 18 forms the stop surface for the valve spring 10, as is indicated by way of example in FIGS. 2a and 3a. At the end opposite of the fastening section 17, the free section 18 has an end portion 19 which is in mesh with one of the contact surfaces 12,13. As can be seen in FIGS. 2 and 3, the contact surfaces 12,13 are arranged on the side of the outlet opening 11 which is opposite of the fastening section 17, and so the stop plates 6a,7a are supported on both ends. The fastening section 17, together with a fastening section of the valve spring 10, is riveted to the valve plate 9.

[0051] The first stop plate 6a differs from the second stop plate 7a particularly with regard to the length, i.e. the extension from the end portion 19 to the opposite end of the fastening section 17, and with regard to the curvature. As a result, the contact with one of the contact surfaces 12,13 can be ensured in a simple manner by the dimensioning of the length and the curvature of the stop plates 6a,7a in accordance with the standard distance and the radial distance of the contact surfaces 12,13.

[0052] FIG. 4 shows a three-dimensional drawing of the cylinder head cover 8 according to the invention, showing particularly the arrangement of the contact surfaces 12,13 and the design of the support element 14. It further shows the sealing surface 16 and the, in this embodiment, four fastening openings 23 which are arranged on the side of the cylinder head cover 8 that faces the valve plate 9. The fastening openings 23, which correspond to corresponding openings in the valve plate 9 and threaded holes in the cylinder housing 3, are used to receive fastening means, such as screws, by means of which the cylinder head cover 8 is fastened to the cylinder housing 3. By tightening the fastening means, the sealing element 15 is deformed to seal the hollow space and the cylinder, and the stop plate 6a,7a is elastically deformed and thus pre-stressed by the contact with the contact surface 12,13.

LIST OF REFERENCE SIGNS

[0053] 1 Compressor housing [0054] 2 Electric drive unit [0055] 3 Cylinder housing [0056] 4 Piston [0057] 5 Crankshaft [0058] 6 First outlet valve [0059] 6a First stop plate [0060] 7 Second outlet valve [0061] 7a Second stop plate [0062] 8 Cylinder head cover [0063] 9 Valve plate [0064] 10 Valve spring [0065] 11 Outlet opening [0066] 12 First contact surface [0067] 13 Second contact surface [0068] 14 Support element [0069] 15 Sealing element [0070] 16 Sealing surface [0071] 17 Fastening section [0072] 18 Free section [0073] 19 End portion of the free section [0074] 20 Suction silencer [0075] 21 Cylinder head arrangement [0076] 22 Longitudinal axis of the outlet opening 11 [0077] 23 Fastening opening [0078] 24 Bulge