GB2165317A

GB2165317A - Improvements in or relating to piston compressors

Info

Publication number: GB2165317A
Application number: GB08517796A
Authority: GB
Inventors: Friedrich Bauer
Original assignee: ENFO Grundlagen Forschungs AG
Current assignee: ENFO Grundlagen Forschungs AG
Priority date: 1984-07-27
Filing date: 1985-07-15
Publication date: 1986-04-09
Also published as: FR2568320A1; IT8521566A0; IT1200677B; GB2165317B; DE3526255A1; GB8517796D0

Abstract

A piston compressor is provided with a combined suction and pressure valve, which has a common valve seating plate (8) arranged between the cylinder (1) and the cylinder head (4). The valve seating plate (8) is provided with suction channels (11) and a split ring suction plate (13) and with at least one pressure channel (12) and a tongue- shaped pressure plate (16). The pressure channel (12) is arranged in the region enclosed by the suction plate (13) and the pressure plate (16) is secured by screws 17 outside the circumference of the suction plate (13) on the valve seating plate (8). The suction plate (13) comprises a spring ring which is open or split at one point, one end being secured by screws (14) on the valve seating plate (8) and the other being freely movable to an end stop. The pressure plate (16) crosses over the suction plate (13) in the region of its secured end, in which no suction channels are provided. <IMAGE>

Description

SPECIFICATION Improvements in or relating to piston compressors The invention relates to a piston compressor of the type having a combined suction and pressure valve, which has a common valve seating plate arranged between the cylinder and the cylinder head of the compressor and provided with suction channels and an annular -suction plate and with at least one pressure channel arranged in the region enclosed by the suction plate and a tongue-shaped pressure plate, which is secured outside the circumfer ence of the annular suction plate on the valve seating plate.

Piston compressors of this type are already known. British Patent 737 908 discloses a piston compressor the approximately annular suction plate of which is clamped on one side between the cylinder and the valve seating plate and controls the suction channels with its free end. In its inner region the suction plate has a recess, above which pressure channels are provided in the valve seating which are controlled by means of a pressure plate which crosses over the suction plate in the manner of an arc. This arrangement allows for a relatively simple design of the cylinder head with a diametrically projecting dividing wall between the suction chamber and the compression chamber. Only a relatively small portion of the cylinder surface is, however, provided for the suction channels.

Further piston compressors with combined valves are known from Austrian Patent 265 337, British Patent 839 169 and US Patent 2 984 408. In these patents both the suction valves and the pressure valves plates which penetrate the cylinder diametrically and which are formed in the shape of a tongue. The pressure channels are provided laterally adja cent the suction plates so that the conveyed medium can flow through them. This valve design allows for only small cross sectional areas of passage of the suction channels rela tive to the cross sectional area of the cylinder of the compressor, on account of which this design is only suitable for large compressors and those embodiments of which only low re quirements are made with respect to convey ing performance.

In the case of the combined compressor valve which is also known from German Pa tent 866 712, both the suction plate and the pressure plate comprise respectively a ring which is connected to a hub by means of webs. The hubs of both plates are secured on the valve seating plate with a screw which is arranged in the valve axis. This valve design allows for suction channels in the valve sea ting plate which project circularly, but requires complicated guiding of the channels and diverting the flow of the conveyed medium in the valve seating plate, so that production is expensive and pressure losses during the passage of the medium through the valves high.

According to the invention, there is provided a piston compressor comprising a combined suction and pressure valve having a common valve seating plate which is arranged between a cylinder and a cylinder head of the compressor and which is provided with suction channels, with an annular suction plate, with at least one pressure channel which is arranged in a region enclosed by the suction plate, and with a tongue shaped pressure plate which is secured outside the circumference of the annular suction plate on the valve seating plate, the suction plate comprising a spring ring which is open at one point and which is clamped by one end to the valve seating plate but is freely movable at its other end, the pressure plate crossing the annular suction plate in a region which surrounds the securing point of the suction plate and, in which no suction channels are provided, the pressure plate extending in a substantially radial direction to the pressure channel.

It is thus possible to provide piston compressors such that, in the case of small spatial requirements, simple structure and frictionless guiding of the closure plates of the valves, and relatively large cross sectional areas of passage, in particular of the suction valve, are possible and a small clearance can be obtained.

A simple design of the compressor valves can be provided which meets all requirements made of valves of this type to the full in a surprising way. Both closure plates are guided so as to be frictionless, without taking up additional space for performing the guiding or for possible guides.

The annular suction plate allows for the arrangement of suction channels across a wide area of the cylinder circumference near the cylinder edge, so that a large cross sectional area of passage can be accommodated by the valve seating plate. By means of the arrangement of the pressure plates in a region in which the suction plate is lifted only slightly off the valve seating plate and where no passage channels of the suction valve are provided, the suction valve is not impaired by the pressure valve. The closure plates can be se cured simply on the valve seating plate, e.g.

by screws. The clearance of the piston com pressor can be kept small and the cylinder head can also have a relatively simple form.

Compressor valves are known from Swiss Patent 38 61 7 with a suction plate which comprises a spring ring which is open at one point and is clamped by one end on the valve seating plate, and which is freely movable by its other end up to an end stop. In this case, simple annular valves are involved which can be used both as a suction valve or a pressure valve and can be inserted into valve recesses of the compressor. Contrastingly, in the case of the invention it is not the design of the closure plate which is involved per se, but a particular spatial arrangement of the suction plate and the pressure plate relative to one another.

In a preferred embodiment of the invention the longitudinal axis of the pressure plate is arranged at least approximately in the axial plane of the compressor which passes through the securing point of the suction plate. In this way, maximum use is made of the space provided for the valves.

In a further embodiment of the invention the piston compressor can be formed in such a way that the suction plate at its outer edge projects across at least a portion of its width into a annular groove shaped recess in the cylinder wall which communicates with the valve seating plate and which forms the end stop for the lifting movement. In this embodiment the suction plate is arranged so as to be protected and an end stop, which avoids too large a deflection, is associated therewith about its entire circumference. Further, this arrangement allows for an additional increase in the cross sectional area of passage, because the graduated circle, on which the suction channels are recessed in the valve seating plate, is also enlarged with the enlargement of the outer circumference beyond the cylinder edge.

In order to prevent a disadvantageous enlargement of the clearance, the suction plate may surround concentrically a projection which projects from the piston head in the axial direction of the cylinder and which projects into the pressure channel of the valve seating plate in the upper dead centre position of the piston.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows an axial middle section through the upper part of a compressor with cylinder head and valves; and Figure 2 shows a cross-section on line ll-ll in Fig. 1.

The compressor comprises a cylinder 1 with a cylinder borehole 2, in which a piston 3 is displaceable. Above the cylinder 1, a cylinder head 4 is provided which has a suction chamber 5 and a pressure chamber 6, which are separated from one another by a dividing wall 7. Between the cylinder 1 and the cylinder head 4 a valve seating plate 8 is clamped which is sealed with a sealing ring 9 against the cylinder 1 and against the cylinder head 4 with a sealing disc 10.

In the valve seating plate 8, a plurality of suction channels 11 are arranged on a graduated circle which is concentric to the cylinder axis and a pressure channel 12 is arranged in the cylinder axis. An annular suction plate 13, which is secured on the valve seating plate 8 at one end by two screws 14 provided on the securing point and which is associated with the suction channels 11, covers all suction channels 11 and can be lifted off the suction channels 11 resiliently in an annular groove shaped recess 15 of the cylinder 1. The pressure valve comprises a tongue-shaped pressure plate 16 which covers the pressure channel 12 and is secured on the valve seating plate 8 by means of screws 17. A projecting rib 18 in the pressure chamber 6 forms an end stop for the lifting movement of the pressure plate 16.It can also be seen from Fig. 1 that the piston 3 has a projection 19 which projects in an axial direction, and which projects coaxially through the suction plate 13 into the pressure channel 12 of the valve seating plate 8.

The pressure plate 16 is secured by means of screws 17 outside the circumference of the suction plate and extends by its free end in an approximately radial direction to the pressure channel 12. As can be seen in particular from Fig. 2, the pressure plate 16 crosses over the annular suction plate 13 in the region of the securing point of the suction plate 13, i.e.

near the securing screws 14, in which region no suction channels 11 are provided in the valve seating plate 8. There is therefore no loss of space for the suction channels 11 in this arrangement as a result of the pressure plate 16, so that the suction channels can occupy a large cross section.

In the embodiment the longitudinal axis of the pressure plate 16 projects approximately in the axial plane of the compressor which passes through the securing point 4 of the suction plate 13, as a result of which there is maximum use of space. Since the suction plate 13, however, also lifts only slightly off the valve seating plate 8 in the region in communication with with the securing point, no appreciable cross sectional area of passage can be cleared in this section either.

The pressure plate 16 can also, therefore, deviate from the optimum arrangement shown in the embodiment and cross over the suction plate 13 laterally adjacent the securing point 14.

The dividing wall 7 between the suction chamber 5 and the pressure chamber 6 projects concentrically to the pressure channel 12, so that the cylinder head 4 also has a simple and clear shape. The annular groove shaped recess 15 in the cylinder 1 forms an end stop for the annular suction plate 13 in its lifting movement, which at least projects by its outer edge into the recess 15. The projection 19 of the piston 3, which fills up the pressure channel 12 in the dead centre position of the piston, effects a small clearance space of the compressor.

Claims

1. A piston compressor comprising a com bined suction and pressure valve having a common valve seating plate which is arranged between a cylinder and a cylinder head of the compressor and which is provided with suction channels, with an annular suction plate, with at least one pressure channel which is arranged in a region enclosed by the suction plate, and with a tongue shaped pressure plate which is secured outside the circumference of the annular suction plate on the valve seating plate, the suction plate comprising a spring ring which is open at one point and which is clamped by one end to the valve seating plate but is freely movable at its other end, the pressure plate crossing the annular suction plate in a region which surrounds the securing point of the suction plate and, in which no suction channels are provided, the pressure plate extending in a substantially radial direction to the pressure channel.

2. A piston compressor as claimed in claim 1, in which the longitudinal axis of the pressure plate is disposed substantially in an axial plane of the compressor which passes through the securing point of the suction plate.

3. A piston compressor as claimed in claim 1 or 2, in which the suction plate on its outer edge projects across at least a portion of its width into an annular groove shaped recess in the cylinder wall which communicates with the valve seating plate and which forms an end stop for lifting movement.

4. A piston compressor as claimed in any one of the preceding claims, in which the suction plate surrounds concentrically a projection which projects from a piston head in the axial direction of the cylinder and which projects in the top dead centre point of the piston into the pressure channel of the valve seating plate.

5. A piston compressor substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.