Reciprocating compressor and method for operating a reciprocating compressor

Abstract

The invention relates to a reciprocating compressor, comprising: a cylinder; a piston able to move linearly inside the cylinder; an oil circuit for building up a film of oil in a gap between an inner wall of the cylinder and the piston; an electric oil pump which can be activated separately from the piston and pumps oil from an oil sump into the oil circuit, the oil pump having a further cylinder in which a further piston is able to move linearly, the further piston being able to be magnetized, the further cylinder having a compression chamber fluidically connected to the oil sump and to the oil circuit, and the oil pump having a coil for generating a magnetic field, in order to magnetically make the further piston move linearly; and a control device configured to activate the further piston by energizing the coil, in such a way that the energizing of the coil generates a magnetic field by means of which the further piston is magnetically made to move linearly in order to modify a compression volume of the compression chamber for the purpose of pumping oil from the oil sump into the oil circuit, wherein the control device is configured to activate the further piston independently of the piston. The invention relates to a method for operating a reciprocating compressor, to a computer program and to a machine-readable storage medium.

Description

[0001] R. 412008

[0002] - 1 -

[0003] Description

[0004] title

[0005] Reciprocating compressor and method for operating a reciprocating compressor

[0006] The invention relates to a reciprocating compressor, a method for operating a reciprocating compressor, a computer program and a machine-readable storage medium.

[0007] State of the art

[0008] For the lubrication and sealing of reciprocating compressors, an oil film in the gap between the piston and cylinder is necessary. Various oil pump principles are used to create the oil circuit. In these systems, the oil pump is driven by the movement of the entire compressor. The delivery rate is therefore directly linked to the movement of the compressor. In the event of a leak in the oil circuit, it is only refilled after the compressor starts. The formation of the oil film in the relevant gap therefore occurs with a time delay.

[0009] Patent US 8,070,460 B2 discloses a reciprocating pump.

[0010] Disclosure of the invention

[0011] The object underlying the invention is to provide a concept that enables an oil supply to a reciprocating compressor that is independent of compressor movement. R. 412008

[0012] - 2 -

[0013] This problem is solved by means of the respective subject matter of the independent claims. Advantageous embodiments of the invention are the subject matter of dependent claims.

[0014] According to a first aspect, a reciprocating compressor is provided, comprising: a cylinder, a piston arranged to move linearly within the cylinder, an oil circuit for building up an oil film in a gap between an inner wall of the cylinder and the piston, an electric oil pump controllable separately from the piston for pumping oil from an oil sump into the oil circuit, wherein the oil pump has a further cylinder in which a further piston is arranged to move linearly, wherein the further piston is magnetizable, wherein the further cylinder has a compression chamber which is fluidly connected to the oil sump and to the oil circuit, wherein the oil pump has a coil for generating a magnetic field in order to move the further piston magnetically in a linear fashion, a control device which is configured to actuate the further piston by energizing the coil such that a magnetic field is generated when the coil is energized.by means of which the further piston is moved magnetically in a linear fashion to change a compression volume of the compression chamber in order to pump oil from the oil sump into the oil circuit, wherein the control device is configured to actuate the further piston independently of the piston.

[0015] Following a second aspect, a procedure for operating a reciprocating compressor according to the first aspect is provided, comprising the following steps:

[0016] The control device actuates the second piston by energizing the coil such that a magnetic field is generated by the coil, by means of which the second piston is moved linearly by magnetic force to change the compression volume of the compression chamber in order to pump oil from the oil sump into the oil circuit. R. 412008

[0017] - 3 -

[0018] According to a third aspect, a computer program is provided, comprising commands which, when the computer program is executed by the control unit of the reciprocating compressor according to the first aspect, cause it to execute a procedure according to the second aspect.

[0019] According to a fourth aspect, a machine-readable storage medium is provided on which the computer program is stored according to the third aspect.

[0020] The invention is based on the understanding that the above problem is solved by providing the reciprocating compressor with an electric oil pump that can be controlled independently of the piston. This electric oil pump can draw oil from an oil sump into the oil circuit to build up an oil film in the gap between the inner wall of the cylinder and the piston. Because this electric oil pump can be controlled independently of the piston, the oil film in the gap between the inner wall of the cylinder and the piston can be built up independently of any movement of the reciprocating compressor, and in particular, of any movement of the piston. This makes it advantageously possible, for example, to build up the oil film even before the piston moves linearly within the cylinder.In other words, this makes it advantageously possible to start the oil supply even before the compressor starts, in order to build up the oil film.

[0021] This advantageously avoids a dry start. Because the oil supply is independent of compressor movement, an on-demand oil delivery rate can be advantageously achieved.

[0022] The concept described here is based on an independently controlled electric oil pump that generates a pumping effect by changing the volume in the compression chamber. The independent electric control advantageously decouples the oil delivery from the operating state of the overall compressor. According to R. 412008 described here.

[0023] - 4 -

[0024] In this concept, a magnetic field is generated via an electric coil. This magnetic field causes a relative movement between the second piston and the second cylinder, resulting in a linear magnetic movement of the second piston. The resulting change in the volume of the compression chamber advantageously creates a pumping effect, which draws oil from the sump into the oil circuit, thus transferring oil from the sump into the oil circuit.

[0025] In one embodiment of the piston compressor, it is provided that the compression chamber is fluidly connected to the oil sump and to the oil circuit via a check valve in such a way that the corresponding check valve only allows one flow direction from the oil sump into the compression chamber and from the compression chamber into the oil circuit, respectively.

[0026] This results, for example, in the technical advantage that the oil can be efficiently pumped from the oil sump through the compression chamber into the oil circuit.

[0027] According to this embodiment, the compression chamber is fluidically connected to the oil sump via a first check valve in such a way that the first check valve only allows one flow direction from the oil sump into the compression chamber, wherein the compression chamber is fluidly connected to the oil circuit via a second check valve in such a way that the second check valve only allows one flow direction from the compression chamber into the oil circuit.

[0028] In one embodiment of the reciprocating compressor, it is provided that the further piston is arranged at least partially inside the coil.

[0029] This results, for example, in the technical advantage that the generated magnetic field can act efficiently on the other piston. R. 412008

[0030] - 5 - In one embodiment of the reciprocating compressor, it is provided that the control device is configured to control the further piston independently of an operating state of the reciprocating compressor.

[0031] This results, for example, in the technical advantage that the oil film can be built up independently of the operating condition of the reciprocating compressor.

[0032] In one embodiment of the method, it is provided that the further piston is controlled by the control device independently of the operating state of the reciprocating compressor.

[0033] This results, for example, in the technical advantage that the oil film can be built up independently of the operating condition of the reciprocating compressor.

[0034] The process characteristics are derived analogously from the characteristics of the reciprocating compressor, and vice versa. Statements made in connection with the process apply analogously to the reciprocating compressor, and vice versa.

[0035] The method is, for example, a computer-implemented method.

[0036] The control unit is, for example, programmed to execute the computer program.

[0037] The fact that the further piston is magnetizable means in particular that the further piston consists of or is formed from one or more magnetizable materials or comprises one or more such materials.

[0038] Examples of materials include: Ferritic steel, martensitic steel and neodymium (NdFeB).

[0039] The invention is explained in more detail below with reference to preferred embodiments. Figure 412008 shows:

[0040] - 6 -

[0041] Fig. 1 shows a reciprocating compressor,

[0042] Fig. 2 shows a flowchart of a method for operating a reciprocating compressor and

[0043] Fig. 3 shows a machine-readable storage medium.

[0044] Fig. 1 shows a reciprocating piston compressor 101 in a schematic representation.

[0045] The reciprocating compressor 101 comprises a cylinder 103 and a piston 105, which is arranged to be linearly movable within the cylinder 103.

[0046] For clarity, cylinder 103 and piston 105 are shown in a truncated view.

[0047] The reciprocating compressor 101 includes an oil circuit 107 for building up an oil film in a gap 109 between an inner wall 111 of the cylinder 103 and the piston 105.

[0048] Furthermore, the reciprocating compressor 101 includes an electric oil pump 113, which can be controlled separately from the piston 105, for pumping oil from an oil sump 115 into the oil circuit 107.

[0049] The oil pump 113 has a further cylinder 117 in which another piston 119 is arranged. The further piston 119 is magnetizable.

[0050] The further cylinder 117 has a compression chamber 121, which is fluidly connected to the oil sump 115 and to the oil circuit 107.

[0051] The reciprocating compressor 101 includes a control device 123, which is configured to actuate the further piston 119 by energizing a coil 124 of the electric oil pump 113 in such a way that when the coil 124 is energized, a magnetic field is generated by means of which the further piston 119 R. 412008

[0052] - 7 - is moved linearly by magnetic force to change the compression volume of the compression chamber in order to pump oil from the oil sump into the oil circuit to build up the oil film in the gap 109. The control device 123 is configured to actuate the further piston 119 independently of the piston 105. The further piston 119 is arranged at least partially inside the coil 124.

[0053] The reciprocating compressor 101 includes a power source 125 that provides the electrical current. The control unit 123 is configured to control the power source 125 such that it provides the required electrical current.

[0054] By energizing the coil 124, a magnetic field is generated, by means of which the further piston 119 is moved linearly within the further cylinder 117, so that the compression volume of the compression chamber 121 is increased or decreased accordingly, so that a pumping effect is effected to pump oil from the oil sump 115 into the oil circuit 107.

[0055] Fig. 1 schematically shows the further piston 119 in two positions: once drawn with solid lines, once drawn with dashed lines with the reference numeral 127.

[0056] The compression chamber 121 is connected to the oil sump 115 via a first check valve 129 such that the first check valve only allows flow from the oil sump 115 into the compression chamber 121. This flow direction is indicated by a first arrow with the reference numeral 131.

[0057] The compression chamber 121 is connected to the oil circuit 107 via a second check valve 133 such that the second check valve 133 only allows flow from the compression chamber 121 into the oil circuit 107. This flow direction is indicated by a second arrow with the reference numeral 135. R. 412008

[0058] - 8 -

[0059] The oil circuit 107 includes a supply line 137, which leads from the compression chamber 121 to the gap 109. The oil circuit 107 includes a return line 139, which leads from the gap 109 back to the oil sump 115.

[0060] Oil is thus pumped by the oil pump 113 from the oil sump 115 via the supply line 137 to the gap 109 in order to build up an oil film in the gap 109. Oil is then pumped back to the oil sump 115 via the return line 139.

[0061] The second piston has a first side 141 and a second side 143 opposite the first side 141, which defines the compression chamber 121. Both sides 141 and 143 are end faces of the second piston 119.

[0062] Fig. 2 shows a flowchart of a method for operating a reciprocating compressor according to the first aspect, comprising the following steps:

[0063] The control device 201 actuates the further piston by energizing the coil 203 in such a way that a magnetic field is generated by the coil, by means of which the further piston is moved magnetically linearly in order to change a compression volume of the compression chamber in order to pump oil from the oil sump into the oil circuit.

[0064] Fig. 3 shows a machine-readable storage medium 301 on which a computer program 303 is stored. The computer program 303 comprises instructions which, when executed by the control unit of the reciprocating compressor according to the first aspect, cause it to execute a procedure according to the second aspect.

Claims

R. 412008 - 9 - Claims 1. Reciprocating compressor (101) comprising: a cylinder (103), a piston (105) arranged to move linearly within the cylinder (103), an oil circuit (107) for building up an oil film in a gap (109) between an inner wall (111) of the cylinder (103) and the piston (105), an electric oil pump (113) controllable separately from the piston (105) for pumping oil from an oil sump (115) into the oil circuit (107), wherein the oil pump has a further cylinder (117) in which a further piston (105) is arranged to move linearly, wherein the further piston (105) is magnetizable, wherein the further cylinder (117) has a compression chamber (121) which is fluidly connected to the oil sump (115) and to the oil circuit (107), wherein the oil pump has a coil for generating a a magnetic field to move the further piston (105) magnetically linearly, a control device (123) which is set up,to actuate the further piston (105) by energizing the coil in such a way that a magnetic field is generated when the coil is energized, by means of which the further piston (105) is moved linearly by magnetic force to change a compression volume of the compression chamber (121) in order to pump oil from the oil sump (115) into the oil circuit (107), wherein the control device (123) is configured to actuate the further piston (105) independently of the piston (105).

2. Reciprocating compressor (101) according to claim 1, wherein the compression chamber (121) is fluidically connected to the oil sump (115) and to the oil circuit (107) via a check valve (129, 133) in such a way that the corresponding check valve (129, 133) only allows one flow direction from the oil sump (115) into the compression chamber (121) and from the compression chamber (121) into the oil circuit (107). R. 412008 - 10 - 3. Reciprocating piston compressor (101) according to claim 1 or 2, wherein the further piston (105) is arranged at least partially inside the coil.

4. Reciprocating piston compressor (101) according to one of the preceding claims, wherein the control device (123) is configured to control the further piston (105) independently of an operating state of the reciprocating piston compressor (101).

5. Method for operating a reciprocating compressor (101) according to any of the preceding claims, comprising the following steps: Control (201) of the further piston (105) by the control device (123) by energizing (203) the coil such that a magnetic field is generated by the coil, by means of which the further piston (105) is moved magnetically linearly in order to change a compression volume of the compression chamber (121) in order to pump oil from the oil sump (115) into the oil circuit (107).

6. Method according to claim 5 with respect to the reciprocating compressor (101) referred back to claim 4, wherein the further piston (105) is controlled by the control device (123) independently of an operating state of the reciprocating compressor (101).

7. Computer program (303) comprising commands which, when the computer program (303) is executed by the control device (123) of the reciprocating compressor (101) according to one of claims 1 to 4, cause it to execute a method according to claim 5 or claim 6.

8. Machine-readable storage medium (301) on which the computer program (303) according to claim 7 is stored.

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