DE102017106147B4 - Reciprocating machine with cooling device - Google Patents

Abstract

The invention relates to a reciprocating piston machine for compressing a fluid, in particular ambient air, for a compressed air system of a motor vehicle, comprising a cylinder housing (1), a piston which can be moved up and down in the piston chamber (4, 5) of the cylinder housing (1), and a cylinder head with a valve support plate (9), a cooling duct (6, 7, 8, 10, 13, 16) being provided for cooling at least a partial area of the cylinder head which runs at least in sections through the valve support plate (9). To improve the cooling effect it is proposed that the cooling channel (6, 7, 8, 10, 13, 16) has a section which runs through the cylinder housing (1), with at least one connecting section (11, 12, 14, 15) in the valve support plate (9 ) is provided which connects the cooling channel section (10, 13, 16) of the valve support plate (9) to the cylinder housing section (6, 7, 8).

Description

The invention relates to a reciprocating piston machine for compressing a fluid, in particular ambient air, for a compressed air system of a motor vehicle.

Such reciprocating piston machines are known and comprise a cylinder housing, a piston which can be moved up and down in the piston space of the cylinder housing, and a cylinder head with a valve support plate. For cooling, a cooling channel is provided which runs through at least a partial area of the cylinder head.

In order to improve the performance of the compressor, it is particularly important to ensure efficient cooling of the top dead center area. The dead center area or the dead volume is the area between the valve carrier plate and the upper piston position. This is the area where the greatest heat is generated during operation. If the heat build-up is too great, the result is that the oil ejection increases, as the fitting dimensions between the piston rings and the cylinder change unfavorably. Using an oil separator, the oil must then be extracted or separated from the compressed air.

In order to dissipate the heat from this area, cooling fins and cooling channels are known. In the DE 10 2009 011 214 A1 For example, a compressor is disclosed which comprises a cylinder space in which an inner liner made of a stable material such as gray cast iron is used, with an annular gap being provided between the inner liner and the cylinder housing, which is used as a cooling channel. With this structure, the housing can be made of a light material such as aluminum, so that good heat dissipation is guaranteed.

Furthermore, from the JP11173209A a cylinder housing is known that has a cooling water channel cast into the cylinder housing.

Another solution for cooling the upper dead volume area is in the EP 2 708 746 A1 disclosed. A hollow valve support plate through which a flow of cooling medium flows is used here.

From the DE 10 2005 059 491 A1 Another piston compressor is known whose cylinder housing expands a coolant connection as an inlet for the coolant, with another coolant connection as an outlet for the coolant either on the cylinder head or also on the cylinder housing, so that the coolant flows around the cylinder housing on both sides.

One of the objects of the invention is to propose an alternative, improved construction of the cylinder head area of a reciprocating piston engine, which allows a more efficient cooling of the dead volume area and at the same time reduces the oil ejection.

According to the invention, this object is achieved with a reciprocating piston engine according to claim 1. Further advantageous configurations and preferred solution variants are described in the dependent claims.

According to the invention, a reciprocating piston machine for compressing a fluid, in particular ambient air, is proposed for a compressed air system of a motor vehicle. This comprises a cylinder housing, a piston that can be moved up and down in the piston chamber of the cylinder housing, and a cylinder head with a valve carrier plate, a cooling channel for cooling at least a partial area of the cylinder head being provided, which runs at least in sections through the valve carrier plate.

To improve the cooling, it is provided that the cooling channel has a section that runs through the cylinder housing, at least one connecting section being provided in the valve carrier plate, which connects the cooling channel section of the valve carrier plate to the cylinder housing section.

According to the invention, a single cooling channel is provided which runs through the valve support plate and a partial area of the cylinder housing and consists of several partial sections. The section of the cooling channel that runs through the cylinder housing can be designed to be open towards the valve support plate, so that it can easily be cast along with the casting of the cylinder housing.

In a preferred embodiment, the reciprocating piston machine has a pre-compression stage and a post-compression stage, the piston chamber of the post-compression stage being completely flowed around. With increasing compression, the temperature of the compressed air also increases, so that the maximum temperature arises in the dead volume area, the upper cylinder area, of the booster stage. At least this area requires improved cooling, which is achieved by completely flowing around the dead volume area of the booster stage.

Furthermore, the cooling channel sections are incorporated into the cylinder housing on the front side in such a way that they are covered by the valve support plate. The sealing of the channels in the cylinder housing is on the face side in the contact planes with the Valve carrier plate incorporated into the cylinder housing and is closed or sealed by means of the valve carrier plate. A seal can also be provided between the cylinder housing and the valve carrier. The channels introduced on the end face can be easily produced in a mold by means of cores that can be demolded.

The cooling channel sections can have a depth of 5 to 40 mm. Furthermore, the width of the channels can be adapted to the circumstances and the space available. The width and depth of the channels are preferably adapted to the required flow volume.

To further improve the cooling effect, the cooling medium flow can be divided by the course of the cooling duct sections, so that the flow around the booster stage on both sides.

Furthermore, the cooling channel section between the compressor stages can be designed to be deeper than the outside circumferential cooling channel sections. The deeper the channel section is made between the cylinders, the smaller the distance between them can be selected. In this case, depths of 25-40mm are preferred in order to achieve sufficient air flow.

The cooling medium inlet and the cooling medium drain take place via connections in the valve carrier plate.

According to an advantageous embodiment it is provided that at least the cylinder housing is designed as an aluminum die-cast part, it being possible to use an aluminum alloy which has a hardness of at least 90 HB (Brinell). Such a hardness has been found to be particularly advantageous in investigations.

Further features of the reciprocating piston engine according to the invention and further advantages of the invention emerge from the following description of preferred exemplary embodiments with reference to the drawings.

The invention is explained in more detail below with the aid of sketches.

• 1 eine Ansicht auf das Zylindergehäuse ohne die Ventilsitzplatte
• 2 einen Schnitt durch das Zylindergehäuse
• 3 eine Ansicht auf die Ventilsitzplatte mit dem darunter angeordneten Zylindergehäuse

In these show:

• 1 a view of the cylinder housing without the valve seat plate
• 2 a section through the cylinder housing
• 3 a view of the valve seat plate with the cylinder housing arranged below

1 shows a view of the cylinder housing 1 , without the valve seat plate 9 , a two-stage reciprocating piston machine for compressing a fluid, in particular ambient air, for the compressed air system of a motor vehicle.

In the cylinder housing 1 are two parallel piston spaces 4th , 5 arranged, in each of which a piston, not shown, can be moved up and down. The pistons have different diameters and are connected in series with one another in such a way that the air in the pre-compressor stage 5 pre-compressed and in the post-compression stage 4th is compressed to the desired final pressure.

The more the air is compressed, the higher its temperature. In the area of the upper dead volume 17th the highest temperature is reached in each case, so that there is also the greatest need for cooling here. Especially in the booster stage 4th Because of the temperatures that arise here, the cooling requirement is particularly high.

If the temperature is too high, unwanted oil is thrown out, as the sealing effect of the piston rings against the wall of the cylinder decreases as the temperature rises.

To improve the cooling effect in the dead volume area 17th To achieve a cooling channel is provided, which consists of several cooling channel sections 6th , 7th and 8th exists, which are cast or introduced into the cylinder housing. These channel sections can be produced directly when the cylinder housing is being cast. Provided that these are designed such that they can be demolded. The covering and sealing of the duct sections 6th , 7th and 8th takes place by means of the valve support plate 9 , wherein a sealing element can also be provided.

In the embodiment shown here, the inflow of cooling water takes place via the connecting section 11 in the valve support plate 9 . The cooling water flow is then divided into two partial flows and through the channel sections 6th and 7th left and right on the booster stage 4th passed by. About the connection section 12th the recombined cooling water flow is returned to the valve carrier plate 9 directed.

About the connection section 14th the flow of cooling water enters the channel section 8th and from there over the connecting section 12th back into the valve support plate 9 . The pre-compression stage 5 is therefore not completely flowed around, the interruption of the cooling channel has the advantage that the cylinder housing can be made more compact.

In 2 is the cylinder housing 1 shown in section. The channel sections 6th , 7th and 8th have different depths, the depth being adapted to the corresponding cooling requirements. The indicated dead volume area 17th is designed in such a way that the valves attached to the valve support plate 9 are attached, cannot come into contact with the cylinder or strike against it.

3 is a view of the valve seat plate 9 with the cylinder housing arranged below 1 shown. In this view there are further cooling duct sections 10 , 13th and 16 to recognize. The connecting sections can also be seen 11 , 12th , 14th and 15th through which the cooling water enters the cylinder housing.

If you look at the 1 and 3 the course of the entire cooling duct can be tracked. Via the one in the valve support plate 9 arranged cooling medium inlet 2 the cooling water first reaches the area of the booster stage 4th to remove them from the valve support plate 9 from above and over the partial duct sections 6th and 7th to cool from the side.

The cooling water then flows through the area of the pre-compressor stage 5 , over the cooling duct sections 13th , 8th and 16 that has a lower cooling requirement.

The covering and sealing of the duct sections 10 , 13th and 16 takes place by means of corresponding plates that are assigned to the cylinder head.

In a further embodiment, the channel can also flow through other components of the cylinder head. Alternatively, it is also conceivable that a second cooling channel is passed through the cylinder head, by means of which further subregions of the cylinder head can be cooled.

The other channels in the valve carrier plate are the inlet and outlet channels 18th , 19th , 20th and 21 of the two compressor stages 5 , 4th .

List of reference symbols

1

Cylinder housing

2

Cooling medium supply

3

Coolant drain

4th

Piston chamber booster stage

5

Piston chamber pre-compressor stage

6th

Cooling duct section

7th

Intermediate cooling duct section

8th

Cooling duct section

9

Valve support plate

10

Cooling duct section

11

Connection section

12th

Connection section

13th

Cooling duct section

14th

Connection section

15th

Connection section

16

Cooling duct section

17th

Dead volume area

18th

Intake duct

19th

Compressed air outlet duct

20th

Final pressure outlet duct

21

Intake duct

Claims (8)

Reciprocating piston machine for compressing a fluid, in particular ambient air, for a compressed air system of a motor vehicle, comprising a cylinder housing (1), a piston which can be moved up and down in the piston chamber (4, 5) of the cylinder housing (1), and a cylinder head with a Valve support plate (9), with a cooling channel (6, 7, 8, 10, 13, 16) being provided for cooling at least a partial area of the cylinder head, which runs at least in sections through the valve support plate (9), the cooling channel (6, 7, 8) , 10,13,16) has a section which runs through the cylinder housing (1), at least one connecting section (11, 12, 14, 15) being provided in the valve support plate (9), which connects the cooling duct section (10, 13, 16) connects the valve carrier plate (9) with the cylinder housing section (6, 7, 8), characterized in that the cooling medium inlet (2) and the cooling medium outlet (3) take place via connections in the valve carrier plate (9). Reciprocating engine according to Claim 1 , characterized in that the reciprocating piston machine has a pre-compression stage (5) and a post-compression stage (4), the piston space of the post-compression stage (4) being completely flowed around. Reciprocating engine according to Claim 1 , characterized in that cooling duct sections (6, 7, 8) are incorporated into the cylinder housing (1) on the end face in such a way that they are covered by the valve support plate (9). Reciprocating engine according to Claim 1 , characterized in that the cooling channel sections (6, 7, 8) have a depth of 5 to 40 mm. Reciprocating engine according to Claim 2 , characterized in that the cooling medium flow is divided by cooling channel section valves (6, 7) so that the flow around the booster stage (4) is on both sides. Reciprocating engine according to Claim 1 , characterized in that a cooling channel section (7) between the compressor stages (4, 5) is deeper than the outside circumferential cooling channel sections (6, 7). Reciprocating engine according to Claim 6 , characterized in that the cooling channel sections (7) have a depth of 25 to 40mm. that Reciprocating engine according to Claim 1 , characterized in that the cylinder housing (1) is made from a die-cast aluminum.

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