GB2026107A

GB2026107A - An engine-driven compressor crankshaft seal

Info

Publication number: GB2026107A
Application number: GB7925397A
Authority: GB
Original assignee: Sachs Systemtechnik GmbH
Current assignee: Sachs Systemtechnik GmbH
Priority date: 1978-07-20
Filing date: 1979-07-20
Publication date: 1980-01-30
Also published as: SE7906217L; FR2431612B3; AT362863B; DE2831878A1; FR2431612A1; ATA499479A

Abstract

This invention relates to a reciprocating piston compressor connected to an internal combustion reciprocating piston engine, more particularly as a drive unit for a heat pump or refrigerating machine, the crank spaces 14, 15 of the engine and the compressor having a common partition 16 through which the crankshaft passes and accommodates the bearing 17 for the same, and the two crank spaces are sealed off from one another by a seal. The seal consists of a bush (20) loaded by a spring (21),and a coacting ring (22), the latter being disposed on the crankshaft (13) so as to rotate therewith but so as to be axially displaceable, and bearing axially against a part (38) fixed to the casing. <IMAGE>

Description

SPECIFICATION An engine-driven compressor This invention relates to a reciprocating piston compressor connected to an internal combustion reciprocating piston engine, more particularly as a drive unit for a heat pump or refrigerating machine, the crank spaces of the engine and the compressor having a common partition through which the crankshaft passes and accommodates the bearing for the same, and the two crank spaces are sealed off from one another by a seal.

In known heat pumps, the internal combustion engines are constructed as physically separate units from the compressors, and the compressor is driven either via a V-belt or a shaft coupling. A construction of this kind is relatively expensive to manufacture, requires a considerable amount of space, and is very heavy.

It is also known to couple a refrigeration compressor directly to a multi-cylinder Diesel engine, one of the Diesel engine cylinders being replaced by a refrigerating compressor cylinder. This construction does not disclose any details for the construction of the seal for the compressor crank space in relation to the engine crank space, nor does this known construction reveal anything concerning the crankshaft seal arrangement.

The object of this invention is to provide a perfect seal between the engine crank space and the compressor crank space, of simple construction, inexpensive manufacture, easy installation and perfect operation irrespective of the axial play of the crankshaft.

To this end, according to the invention, the seal consists of a bush loaded by a spring, and a co-acting ring, the latter being disposed on the crankshaft so as to rotate therewith but so as to be axially displaceable, and bearing axially against a part fixed to the casing, so that the force exerted on the co-acting ring by the spring via the bush is compensated for.

This ensures a perfect seal between the two crank spaces. The axial displaceability of the co-acting ring on the crankshaft particularly enables a continuous crankshaft to be used for the compressor and internal combustion engine, the seal being perfect even with a small amount of axial play.

According to one feature of the invention, the seal formed by the bush and the co-acting ring is supplied with oil. This provides a very good seal, because the sealing elements receive liquid thus avoiding the problem of sealing with respect to gas.

The seal on the crankshaft may be disposed either in the engine crank case or in the compressor crank case optionally. Advantageously, the seal is provided near the crankshaft bearing in the partition, the crankshaft having an axially extended bearing surface on which the co-acting ring is mounted so as to rotate with the crankshaft but so as to be axially slidable. According to the invention, the seal formed by the bush and the co-acting ring for the crankshaft is advantageously fed on one side with the refrigerating machine oil in the compressor circuit when the seal is disposed in the engine crank space.

Since the compressor in the refrigerant circuit requires a separate lubrication with refrigerating machine oil, according to one feature of the invention it is advantageous if an oil pump is disposed on the crank pin in the crank space of the compressor and feeds oil on the compressor side to the seal formed by the bush and the co-acting ring. This ensures a very simple supply of refrigerating machine oil to the shaft seal, in which case the higher pressure in the compressor crank space makes it necessary to provide the oil seal on the compressor side to ensure perfect sealing between the two crank spaces.

In a very simple and inexpensive construction according to the invention, the co-acting ring is connected to the inner gearwheel of an oil gear pump or the co-acting ring is integral with the oil pump gearwheel.

According to another feature of the invention, at least one pin extending in the axial direction of the crankshaft and engaging in a corresponding recess in the co-acting ring is provided to connect the ring to the crankshaft so that it rotates therewith. This mounting of the ring on the crankshaft so that it rotates therewith allows the ring to slide axially in a simple manner. According to one feature of the invention, the or each pin is fixed in a disc provided with a cylindrical projection, said disc being connected to the crank pin so as to rotate therewith.

The crankshaft construction is greatly simplified if, according to the invention, the disc connected to the crank pin and having the cylindrical projection bears the journal on which the connecting rod of the compressor is mounted. In this way the crank pin can be made of relatively small diameter so that the seal consisting of the bush and the co-acting ring can also be of small diameter and hence operates at a relatively favourable low rubbing speed. The disc is fixed on the crank pin by a central screw extending axially. Advantageously, according to the invention, a positive connection is provided between the disc and the crank pin.

According to the invention, the seal chamber sealed off from the crank space of the compressor by the bush and co-acting ring communicates via a duct with the engine crank space. Lubricating oil is fed to the seal chamber via the duct, so that the seal formed by the bush and the co-acting ring receives oil on both sides.

Further embodiments and advantages will be apparent from the description of the con struction and operation of the embodiments of the invention explained by way of example hereinafter with reference to the drawings wherein: Figure 1 is a diagram showing the drive unit consisting of the internal combustion reciprocating piston engine and the piston compressor with a shaft disposed in the engine crank space.

Figure 2 is a diagram showing the drive unit, the shaft seal disposed between the crank space spaces being disposed on the crankshaft on the compressor side.

Figure 3 is a heat pump drive unit consisting of a one-cylinder internal combustion reciprocating piston engine and a one-cylinder reciprocating piston compressor, and Figure 4 is an enlarged-scale view of the seal between the crank spaces of the engine and compressor.

The drive unit shown diagrammatically in Figs. 1 and 2 consists of a two-cylinder internal combustion reciprocating piston engine 1 and a two-cylinder reciprocating compressor 2, units 1 and 2 having a common crankshaft 3. A common partition 4 is provided between the crank space of the engine 1 and the crank space of the compressor 2 and bears a bearing 5 for the crankshaft 3. A seal 6 is provided near the partition 4 to seal off the two crank spaces from one another.

In Fig. 1, the seal 6 is in the crankcase space of the engine 1, while the seal chamber 7 facing the crank space of the compressor 2 communicates with the crank space of the compressor 2. In these conditions there is no difficulty in supplying the seal chamber 7 with the oil used for lubricating the compressor 2.

in contrast to Fig. 1, in the embodiment shown in Fig. 2 the shaft seal 6 is disposed in the crankcase space of the compressor 2.

Here again the seal 6 is mounted on the extended bearing of the crankshaft 3 and has a seal chamber 8 facing the crank space of the engine 1 and communicating with that space.

The drive unit for a heat pump or refrigerating machine as shown in Fig. 3 consists of a one-cylinder Diesel engine as the reciprocating engine 10, and a one-cylinder reciprocating compressor 11. The engine 10 and the compressor 11 are disposed in a common engine cylinder block 1 2 and act on the common crankshaft 1 3. A partition 16, which also bears the bearing 1 7 for the crankshaft 13, is provided between the crank space 1 4 of the engine 10 and the crank space 1 5 of the compressor 11. The second crankshaft bearing 1 8 is at the end of the crankshaft 1 3 adjacent the flywheel in the engine casing.To facilitate assembly, the cylinder block 1 2 has a crank case bottom part bolted to the cylinder block 1 2 in the bearing plane.

As shown to an enlarged scale in Fig. 4, the shaft seal consists of a bush 20 which is mounted in the partition 1 6 and which is pressed, by the spring 21, against the coacting ring 22, which is connected to the crankshaft 1 3 so as to rotate therewith. The partition 1 6 is integrated in the engine cylinder block 1 2 and in the crank case bottom part 19. The co-acting ring 22 is integral with the externally toothed inner wheel 23 of the oil pump, inner wheel 23 running in the outer wheel 26. A sleeve 25 is rigidly connected to the partition 1 6 and is sealed off from the latter, the bush carrier 24 being guided and sealed in said sleeve while the spring 21 bears against the sleeve 25 at one end and against the bush carrier 24 at the other end.

Bush 20 is fixed in the carrier 24 and bears axially, as a result of the force of the spring 21, against the co-acting ring 22, which in turn bears against a component 38 fixed to the casing. The co-acting ring 22 is axially slidable on the relatively small-diameter crank pin 27 but is sealed off from the surface of the crank pin. In order to connect the coacting ring 22 to the crankshaft 13 so that it will rotate therewith, the ring 22 has a recess 28 in which a pin 29 engages, said pin 29 being fixed in a disc 31 provided with a cylindrical projection 30. Said disc 31 is rigidly connected to the crankshaft 1 3 by the screw 32 extending axially. A positive connection 34 is provided to secure the disc 31 on the crank pin 27 so that it rotates therewith.

The compressor connecting rod is overhung on the journal 33 which is fixed on the disc 31 or integral therewith. Since the crank pin 27 has a relatively small diameter, the shaft seal consisting of the bush 20 and the coacting ring 22 can also have a small diameter, so that the running speed at the seal is low.

The seal chamber 35 on the compressor side receives lubricating oil or refrigerating machine oil. This is fed by the oil pump consisting of the inner gearwheel 23 and the outer gearwheel 26. The shaft seal consisting of the bush and co-acting ring thus runs in lubricating oil and a liquid seal is thus obtained between the crank space 1 5 of the compressor and the crank space 14 of the engine, perfect sealing of the crank space 1 5 being obtained although it contains gaseous refrigerant under pressure.

A duct 37 connecting the crank space 14 of the engine to the seal chamber 36 is provided near the bearing 1 7 for the crankshaft 1 3 in the partition 16. The lubricating oil used to lubricate the engine passes through this duct 37 into the seal chamber 36, so that the shaft seal consisting of the bush 20 and co-acting ring 22 receives liquid lubricant on both sides.

Axial play of the crankshaft 1 3 simply has the effect that the co-acting ring 22 or the coacting ring integral with the inner gearwheel 23 of the oil pump moves axially on the crank pin 27 but does not perform any axial move ment with respect to the bush 20. To this end, the co-acting ring 22 or the ring integral with the oil pump gearwheel 23 bears axially against the part 38 rigidly connected to the partition 1 6. The fixed part 38 and the Co- acting ring 22 rotating with the crankshaft 1 3 form an axial bearing in these conditions, the bearing load being produced basically by the force of the spring 21, which acts on the coacting ring 22 via the bush carrier 24 and the bush 20.

Claims

1. A reciprocating piston compressor con nected to an internal combustion reciprocating piston engine, more particularly as a drive unit for a heat pump or refrigerating machine, the crank spaces of the engine and the compressor having a common partition through which the crankshaft passes and accommodates the bearing for the same, and the two crank spaces are sealed off from one another by a seal, characterised in that the seal consists of a bush loaded by a spring, and a Co- acting ring, the latter being disposed on the crankshaft so as to rotate therewith but so as to be axially displaceable, and bearing axially against a part fixed to the casing.

2. A drive unit according to claim 1, characterised in that the bush seal consisting of the bush and co-acting ring is not divided at the periphery and the corresponding part of the crankshaft is built-up.

3. A drive unit according to claims 1 and 2, characterised in that the seal formed by the bush and the co-acting ring is supplied with oil.

4. A drive unit according to claims 1 to 3, characterised in that the seal formed by the bush and the co-acting ring for the crankshaft is disposed in the internal combustion engine crank space and one side of it is fed with refrigerating machine oil in the compressor circuit.

5. A drive unit according to claims 1 to 4, characterised in that an oil pump is disposed on the crank pin in the crank space of the compressor and feeds oil on the compressor side to the seal formed by the bush and the co-acting ring.

6. A drive unit according to claims 1 to 5, characterised in that the co-acting ring is connected to the oil pump gearwheel.

7. A drive unit according to claims 1 to 5, characterised in that the co-acting ring is integral with the oil pump gearwheel.

8. A drive unit according to claims 1 to 7, characterised in that at least one pin extending in the axial direction of the crankshaft and engaging in a corresponding recess in the Co- acting ring is provided to connect the Co- acting ring to the crankshaft so that it rotates therewith.

9. A drive unit according to claims 1 to characterised in that the or each pin is fixed in a disc provided with a cylindrical projection, said disc being connected to the crank pin so as to rotate therewith.

10. A drive unit according to claims 1 to 9, characterised in that the disc connected to the crank pin and having the cylindrical projection bears the journal on which the connecting rod of the compressor is mounted.

11. A drive unit according to claims 1 to 10, characterised in that the disc is fixed on the crank pin by a central screw extending axially.

1 2. A drive unit according to claims 1 to 11, characterised in that a positive connection is provided between the disc and the crank pin.

1 3. A drive unit according to claims 1 to 12, characterised in that the seal chamber sealed off from the crank space of the compressor by the bush and co-acting ring communicates via a duct with the engine crank space.

14. A drive unit according to claims 1 to 13, characterised in that lubricating oil is fed to the seal chamber via the duct.