Patent Description:
Encapsulated, especially hermetically sealed, refrigerant compressors have been known for a long time and are mainly used in refrigeration cabinets, such as refrigerators or refrigerated shelves, but can also be used in mobile appliances. The refrigerant process as such has also been known for a long time. Refrigerant is thereby heated by energy absorption from the space to be cooled in an evaporator and finally superheated and pumped to a higher pressure level using the refrigerant compressor having a cylinder and a reciprocating piston. At this higher pressure level the refrigerant is cooled via a condenser and is conveyed back into the evaporator via a throttle, via which throttle the pressure is reduced and the refrigerant is further cooled down, before the cycle starts anew.

The path of the (usually gaseous) refrigerant through the compressor can be described as follows:
The refrigerant enters a compressor shell of the refrigerant compressor, which compressor shell encapsulates a pump unit of the refrigerant compressor, through a suction pipe, which is in the operating state connected to the evaporator of the refrigerant appliance. During a suction cycle, the refrigerant is sucked through a suction muffler, a suction opening of a valve plate, which suction opening is released by a suction valve spring, into a cylinder of the pump unit of the refrigerant compressor. The suction is caused by linear movement of a piston inside the cylinder. During a compression part of a compression and discharge cycle, the refrigerant is compressed within the cylinder by the linear movement of the piston until a discharge valve spring releases a discharge opening of the valve plate. During a discharge part of the compression and discharge cycle, the so compressed refrigerant then flows through the discharge opening of the valve plate into a discharge muffler and leaves the compressor shell through a discharge pipe, which is connected to the discharge muffler by a discharge connection tube. The discharge tube is in the operating state connected to the condenser of the refrigerant appliance.

The pump unit comprises a cranktrain, which includes the piston and is causing the linear movement of the piston inside the cylinder, a crankcase, in which a crankshaft of the cranktrain is mounted, the crankcase also having a cylinder housing, an electric drive unit, which comprises a rotor and a stator, and a cylinder head arrangement. The cylinder head arrangement includes the valve plate, the suction valve spring, the discharge valve spring, the suction muffler and the discharge muffler. The pump unit is supported within the compressor shell on a plurality of support spring assemblies, preferably on four support spring assemblies.

The shell usually comprises a lower shell part and an upper shell part, which are welded together. The discharge pipe and the suction pipe as well as a maintenance pipe (also known as service pipe) are hermetically connected to the shell. As the refrigerant compressor is a stand-alone product, which is integrated into a refrigerant appliance at some stage of the assembly process, the discharge pipe, the suction pipe and the maintenance pipe are also called discharge connector, suction connector and maintenance connector as they are configured to be connected with respective elements with the refrigerant appliance during assembly and/or in the operation state.

The movement of the piston is caused by rotation of the crankshaft, wherein the piston is connected to a crank-pin of the crankshaft via a connecting rod. The electric drive unit is required to facilitate the rotation of the crankshaft, wherein the rotor is fixed to the crankshaft.

Usually an electronic control unit is mounted to an outside surface of the compressor shell, wherein the stator is connected to an electric pass through element (also known as "fusite") via an inner harness and the electronic control unit is connected to the electric pass through element via an outer harness. The electronic control unit powers the stator and thereby controls the rotational speed of the pump unit of the refrigerant compressor.

<CIT> discloses a suction muffler for a refrigerant compressor. In one of the embodiments the suction muffler housing consists of three separate housing parts, wherein the top housing part comprises inlet and outlet of the suction muffler. The middle housing part is placed between the top housing part and a bottom housing part, wherein partition or dividing walls which form the dampening chambers are integrally formed with the middle housing part.

<CIT> discloses a combined suction and discharge muffler, which comprises a first (upper) muffler shell and a second (lower) muffler shell, in which second muffler shell a partition/seperator is inserted to divide the suction muffler cavity in two sub-sections.

It is an object of the invention to provide a suction muffler with a compact design, which is relatively cheap to produce and easy to assemble. A further object of the invention is to provide an optimised muffler design with regard to an external oil circulation.

In order to achieve at least one of the objects set out above in a suction muffler as defined initially it is suggested according to the invention that the suction muffler further comprises an inner housing element, which is inserted into the suction muffler housing, which inner housing element separates the suction muffler volume into the first suction muffler chamber and a second suction muffler chamber. Due to this specific design, the two muffler chambers, which act as resonators required to reduce the noise level of the suction muffler as well as of a pump unit of the refrigerant compressor in general, can be defined in a very simple way. Further the complexity of the lower housing part and of the upper housing part is reduced as the suction muffler chambers are created by the insertable inner housing element, which can also have a relatively simple and straightforward design. As the inner housing element is inserted into the suction muffler housing during assembly, the lower housing part and the upper housing part of the suction muffler housing can be welded together and contain the inner housing part within. Therefore production costs can be lowered and the size of the suction muffler can be reduced with regard to suction mufflers according to the prior art.

According to the invention, the inner housing element comprises, preferably consists of, a top wall and a side wall, wherein the first suction muffler chamber is bounded by the lower housing part, the top wall of the inner housing element and the side wall of the inner housing element, and wherein the top wall has a protruding tubular section, wherein at least a section of the inlet tube is received by the protruding tubular section of the inner housing element. The inner housing element having a top wall and a side wall, which are preferably forming an L-shaped inner housing element, allows for a comparably easy design of the inner housing element and defining the boundaries of the first suction muffler chamber. The protruding tubular section, which forms an opening in the top wall, allows refrigerant to enter the first suction muffler chamber as a section of the inlet tube is received by the protruding tubular section. In order to close the first suction muffler chamber, the outline of the top wall (as seen from a height direction) resembles the outline of the suction muffler housing, especially of the lower housing part. Accordingly, the outline of the side wall of the inner housing element resembles a cross section of the suction muffler housing, especially of the lower housing part, in a plane being parallel to the height direction.

A further embodiment variant of the invention provides that two slots are formed at an inner surface of the lower housing part in order to guide the side wall of the inner housing element during mounting and to support opposite edges of the side wall in the lower housing part. Each slot can be formed by a set of two reinforcement ribs protruding from an inner surface of the lower housing part. The reinforcement ribs are preferably running in parallel to a height direction so that the side wall of the inner housing element can be inserted into the slots in a simple way. The slots are used for supporting and positioning the inner housing element inside the suction muffler housing. They are further used to guide the inner housing element into the correct position during assembly and to fix it there, before the lower housing part and the upper housing part of the suction muffler are mated.

In order to position the inner housing element within the suction muffler housing and to define the first suction muffler chamber, a further embodiment variant of the invention provides that the top wall of the inner housing element is aligned with an upper edge of the lower housing part. The upper edge can be formed as a part of the circumferential fixing groove of the lower housing part.

According to a further embodiment variant of the invention it is provided that the protruding tubular section of the inner housing element is extending perpendicularly to both sides of the top wall of the inner housing element. Because of this design of the inner housing element, the protruding tubular section extends (in the mounted state of the suction muffler) on one side of the top wall inside the upper housing part (and thus into the second suction muffler chamber) in order to form an overlapping section with the suction pipe. On the other side of the top wall, the protruding tubular section of the inner housing element extends into the lower housing part of the suction muffler and thus into the first suction muffler chamber. Accordingly the flow of the refrigerant can be optimised within the suction muffler as the protruding tubular section distributes the refrigerant to the respective portions of the suction muffler housing.

In a further embodiment variant it is provided that the protruding tubular section of the inner housing element and the inlet tube of the upper housing part are oriented in parallel, wherein an air gap is formed between the protruding tubular section of the inner housing element and the inlet tube of the upper housing part, through which air gap refrigerant can flow from the first suction muffler chamber to the second suction muffler chamber. Due to the air gap the protruding tubular section of the inner housing element does not only direct the refrigerant coming from the inlet pipe into the first suction muffler chamber, but also acts as a connector of the first suction muffler chamber and the second muffler chamber. Therefore refrigerant can flow from the first suction muffler chamber and the second muffler chamber through the air gap, which further optimises the refrigerant flow and the noise dampening characteristics of the suction muffler.

In order to further improve the flow characteristics of the refrigerant within the suction muffler a further embodiment variant of the invention provides that the protruding tubular section of the inner housing element and the inlet tube of the upper housing part are arranged eccentrically to each other. Preferably the eccentric cross section of the air gap resulting from the positioning of inlet tube and protruding tubular section can be used to specifically influence how much refrigerant flows to which specific portion of the second suction muffler chamber.

As the pump unit of the refrigerant compressor is lubricated during operation via oil as a lubricant, that is conveyed by the pump unit and splashed onto the pump unit, droplets of oil can be contained within the refrigerant that is sucked into the suction muffler. In order to prevent that the oil accumulates within the suction muffler and prevents it from functioning properly, the lower housing part has the oil drain opening through which oil can drain from the suction muffler. However as the suction muffler has two separate chambers oil needs to be drained from both chambers. In order to prevent the requirement of having two separate oil drain openings for each suction muffler chamber, a further embodiment variant of the invention provides that the side wall of the inner housing element has an oil opening for allowing oil from one suction muffler chamber to flow to the oil drain opening located in the other suction muffler chamber. Preferably the oil opening is located in a bottom section of the side wall of the inner housing element and is relatively small compared to the cross section of the protruding tubular section of the inner housing element, so that an oil accumulation formed in a bottom section of the lower housing during operation can clos the oil opening and prevents formation of a second flow path from the first suction muffler chamber into the second suction muffler chamber.

In order to improve the oil draining efficiency of the suction muffler, even in case the refrigerant compressor is placed on an inclined surface and thus is not oriented correctly, a further embodiment variant of the invention provides that the oil drain opening is located at a lowest point of an inner surface of the lower housing part, wherein the inner surface is declining toward the oil drain opening at least in sections adjacent to the oil drain opening. Due to this design oil flows towards the oil drain opening even in the afore mentioned case and does not accumulate in the chamber not having an oil drain opening. It is, however, not required that the whole lower part of the inner surface needs to incline towards the oil drain opening as there can be relatively flat sections, if they are not in the direct vicinity of the oil drain opening.

According to a further embodiment variant of the invention the second suction muffler chamber is bounded by the upper housing element, the top wall of the inner housing element, the side wall of the inner housing element and a section of the lower housing part. Thus, both suction muffler chambers are defined and bounded solely by inner surfaces of the lower housing part and the upper housing part as well as by the inner housing element.

A further embodiment variant of the invention provides that the inlet opening is surrounded by an embossing, which embossing is located on an outer surface of the upper housing part. Preferably the embossing is located at an outer surface of the upper housing part. The embossing prevents oil drops which splash onto the suction muffler during operation from directly entering the suction muffler as they are redirected by the embossing and flow along the embossing around the inlet opening.

In a further embodiment variant of the invention it is provided that the embossing is chamfered towards the inlet opening and/or that the embossing has at least two tangential extensions. The chamfering improves the flow characteristics of the refrigerant flowing into the suction muffler whereas the tangential extensions, especially if they are oriented parallel to each other, improve the oil drain from the embossing. It is preferred that the tangential extensions are positioned symmetrical to a vertical symmetry plane of the inlet opening.

Due to the lack of available space within a compressor shell of the refrigerant compressor due to the aim to minimise the size of the refrigerant compressor, it is in some embodiments not possible to place an embossing that projects over the contour of the suction muffler, a further embodiment variant provides that the embossing is located in a recessed area of the outer surface of the upper housing part. Due to the recessed area the available space can be used optimally, while still benefitting from the technical effect of the embossing. It is thus especially preferred that the embossing does not project over the contour of the surrounding non-recessed surfaces of the outer surface of the upper housing part.

A further preferred embodiment variant of the invention provides that the lower housing part has an outer tubular extension which is surrounding the oil drain opening. The outer tubular extension further improves the formation of droplets of oil coming from the oil drain opening and allows the oil to drip off the suction muffler. Preferably the outer tubular extension is spaced apart from the oil drain opening.

The above described characteristics are further improved in another embodiment variant of the compressor which provides that the outer tubular extension of the lower housing part has a diagonal cut, preferably a <NUM>° cut end section.

In a further embodiment variant of the suction muffler it is provided that the outlet section is formed by a suction connector head for connecting the suction muffler with a suction valve of a cylinder head assembly of the refrigerant compressor, which suction connector head has a sealing surface for connection with a valve plate of the refrigerant compressor, wherein the suction connector head is connected with an outlet tube, which is located within the upper housing part. The suction connector head allows to easily establish a secure connection of the suction muffler to the valve plate and seal this connection. The outlet tube within the suction muffler housing is used to further improve the flow characteristics of the refrigerant within the muffler volume, especially within the second suction muffler chamber.

A further embodiment variant of the invention provides that the suction muffler, especially the suction muffler housing, the inner housing element and the suction connector head, is/are made of a polybutylene terephthalate [PBT] based polymer material. Even though other polymer materials having the same material properties can be used for manufacturing suction mufflers, PBT based polymer material based products have been tested to have a superior combination of availability, costs, thermal properties - especially thermal conductivity - and mechanical properties. Furthermore the suction muffler housing is usually produced via injection moulding.

In a further preferred embodiment variant of the suction muffler it is provided that the polymer material is fibre-reinforced, preferably by glass fibres. Fibre-reinforced polymer materials have even further improved characteristics especially with regard to the mechanical stability. Preferably the polymer material used is PBT GF30, which has a <NUM>% share of glass fibres and can be bought under the commercial name Ultradur® B4300G6 from BASF.

The invention further relates to an encapsulated refrigerant compressor having.

wherein the cylinder head assembly comprises the suction muffler according to the invention described above.

The invention will now be explained in more detail below with reference to one exemplary embodiment. The scope of protection is defined by the subject matter of the appended claims. The drawings are provided by way of example and are intended to explain the concept of the invention, but shall in no way restrict it or even render it conclusively, wherein:.

<FIG> shows an outside view of an, in particular hermetically, encapsulated refrigerant compressor <NUM> which extends along a length direction x, a width direction y and a height direction z. Length direction x, width direction y and height direction z form an orthogonal reference system. In general the length dimension of the refrigerant compressor measured along the length direction x is greater than the width dimension measured along the width direction y.

In the following reference will occasionally be made to a (usually gaseous) refrigerant, which flows through the refrigerant compressor <NUM>. It is self evident that these remarks refer to an operating state of the refrigerant compressor <NUM>, but that usually no refrigerant is present in the refrigerant compressor <NUM> when the refrigerant compressor <NUM> is produced or sold as a stand-alone product.

The refrigerant compressor <NUM> comprises a compressor shell <NUM>, which in this embodiment consists of a lower shell part <NUM> and an upper shell part <NUM>. The upper shell part <NUM> and the lower shell part <NUM> are welded together. On both sides of the lower shell part <NUM>, which extend mainly in the length direction x, a supporting base plate <NUM> is fixed to the compressor shell <NUM>. Each supporting base plate <NUM> has two openings <NUM> for mounting support damper assemblies <NUM> (see <FIG>).

A suction pipe <NUM>, which is connectable to a low pressure side of a refrigerant appliance, enters the upper shell part <NUM> on a lateral side of the refrigerant compressor <NUM>. During operation refrigerant is sucked into the refrigerant compressor <NUM> through the suction pipe <NUM>, mainly during a suction cycle of a pump unit <NUM> (see <FIG>) of the refrigerant compressor <NUM>. Therefore, in an operating state, the suction pipe <NUM> is connected directly or indirectly, e.g. through piping of the low pressure side of the refrigerant appliance, to an evaporator of the refrigerant appliance. With regard to the compressor shell <NUM>, the suction pipe <NUM> enters the upper shell part <NUM> through a second connector element <NUM>, which second connector element <NUM> is hermetically connected to the upper shell part <NUM> on the one hand and to the suction pipe <NUM> on the other hand, for example by welding and/or soldering.

A discharge pipe <NUM> as well as a maintenance pipe <NUM> enters the lower shell part <NUM> on a front side of the refrigerant compressor <NUM>. The discharge pipe <NUM> enters the lower shell part <NUM> through a first connector element <NUM>, which first connector element <NUM> is hermetically connected to the lower shell part <NUM> on the one hand and to the discharge pipe <NUM> or maintenance pipe <NUM> respectively on the other hand, for example by welding and/or soldering. During operation, refrigerant compressed by the pump unit <NUM> can escape the refrigerant compressor <NUM> through the discharge pipe <NUM>, mainly during a compression and discharge cycle of the pump unit <NUM>. Therefore, the discharge pipe <NUM> is connectable to a high pressure side of the refrigerant appliance to allow compressed refrigerant to be fed to a high pressure side of the refrigerant appliance. In the operation state the discharge pipe <NUM> is connected directly or indirectly, e.g. through piping of the high pressure side of the refrigerant appliance, to a condenser of the refrigerant appliance.

The maintenance pipe <NUM> can be used to insert lubrication oil and/or refrigerant into the refrigerant compressor <NUM> during assembly of the refrigerant application or during maintenance operations. The maintenance pipe <NUM> is, similar to the suction pipe <NUM>, connected to the lower shell part <NUM> by a second connector element <NUM>, which is hermetically connected to the lower shell part <NUM> on the one hand and to the maintenance pipe <NUM> on the other hand, for example by welding and/or soldering.

With regard to <FIG> all main components of the refrigerant compressor <NUM> as well as their functions will be briefly described. The refrigerant compressor <NUM> comprises the shell <NUM>, an electronic control unit <NUM>, which is detachably mounted to the compressor shell <NUM>, and the pump unit <NUM> (see <FIG>), which is located inside the compressor shell <NUM> and supported by four support spring assemblies <NUM>. The refrigerant compressor <NUM> is mounted on four support damper assemblies <NUM>, which are connected to the respective openings of the two supporting base plates <NUM>. Each support damper assembly <NUM> includes a damper pin <NUM>, an outer dampening element <NUM>, a lining disk <NUM> and a securing element <NUM>.

As can be seen in <FIG>, the suction pipe <NUM> enters the upper shell part <NUM> through a second connection opening <NUM>, whereas the maintenance pipe <NUM> enters the lower shell part <NUM> through a third connection opening <NUM>. Even though not visible in <FIG>, the discharge pipe <NUM> enters the lower shell part <NUM> through a first connection opening.

The pump unit <NUM> comprises an electric drive unit <NUM>, a cranktrain <NUM>, a crankcase <NUM> and a cylinder head assembly <NUM>, which includes a suction muffler <NUM> and a discharge muffler <NUM>.

Each support spring assembly <NUM> comprises a mounting pin <NUM>, which is fixed, preferably welded, to the lower shell part <NUM>, a lower spring pin <NUM>, which is mounted on the respective mounting pin <NUM>, and a support spring <NUM>, which is supported on the lower spring pin <NUM>.

The electric drive unit <NUM> comprises a stator <NUM>, a rotor <NUM> and an inner harness <NUM>. The stator <NUM> has a lower end element <NUM> made of plastic, which lower end element <NUM> comprises four upper spring holders <NUM> for the respective support springs <NUM>. The stator <NUM> is fixed to the crankcase <NUM> via two stator mounting screws <NUM>. The inner harness <NUM> connects the stator <NUM> with an electric pass through element <NUM>, which is located in the compressor shell <NUM>. On the outside of the compressor <NUM> the electronic control unit <NUM> is connected to the electric pass through element <NUM> via an outer harness <NUM>, in order to control the rotation speed of the pump unit <NUM>.

The cranktrain <NUM> comprises a piston <NUM> and a crankshaft <NUM>, which is rotatably mounted inside a main bearing <NUM> of the crankcase <NUM> on the one hand and axially supported on the crankcase <NUM> by a ball bearing <NUM>. The crankshaft <NUM> has a crank pin <NUM> on which a connecting rod <NUM> is mounted, which connecting rod <NUM> connects the crank pin <NUM> with a piston pin <NUM> of the piston <NUM>. The piston pin <NUM> is fixed to the piston <NUM> via a clamping sleeve <NUM> that is inserted into a matching axial opening in the piston <NUM> and the piston pin <NUM>. On a lower end of the crankshaft <NUM>, opposite the end with the crankpin <NUM>, the rotor <NUM> is mounted to the crankshaft <NUM>, preferably via press fitting. Further an oil pickup <NUM> for conveying lubricant from a lubricant sump formed in the lower shell part <NUM> during operation into a lubricant conveying system of the cranktrain <NUM> is mounted to the rotor <NUM> via three mounting rivets <NUM>.

The crankcase <NUM> includes a cylinder housing <NUM>, in which a cylinder <NUM> is formed. The piston <NUM> reciprocates within the cylinder <NUM> during operation of the refrigerant compressor <NUM> in order to suck refrigerant into the cylinder <NUM> during a suction cycle and to compress and discharge the compressed refrigerant during a compression and discharge cycle. On the crankcase <NUM> a set of two first protrusions <NUM> is located on the side opposite of the cylinder housing <NUM> and a set of two second protrusions <NUM> is located on the cylinder housing <NUM> itself. Inner dampening elements <NUM> are attached to each of the first protrusions <NUM> and second protrusions <NUM>, which inner dampening elements <NUM> interact with respective regions of an inner surface of the upper housing part <NUM> in order to dampen vibrations of the pump unit <NUM> during operation and to prevent damages during transport.

In order to establish a suction path and a discharge path for the refrigerant from the suction pipe <NUM> via the cylinder <NUM> to the discharge pipe <NUM>, the cylinder head assembly <NUM> is mounted onto a cylinder head section of the cylinder housing <NUM>. The cylinder head assembly <NUM> comprises a cylinder gasket <NUM>, a suction valve spring <NUM>, a valve plate <NUM> and a discharge valve spring <NUM>, wherein the valve plate <NUM> has a suction opening <NUM> and a discharge opening <NUM>. The cylinder gasket <NUM> and the suction valve spring <NUM> are located on a suction side 530a of the valve plate <NUM>, which suction side 530a faces towards the piston <NUM>. The discharge valve spring <NUM> is located on a discharge side 530b of the valve plate <NUM>, which faces in the opposite direction of the piston <NUM>. When assembled, the valve plate <NUM>, the suction valve spring <NUM> and the cylinder gasket <NUM> are pressed into a valve plate seat <NUM> of the cylinder housing <NUM>, as will be described below in detail.

A suction connector head <NUM> of the suction muffler <NUM> and a discharge connector head <NUM> of the discharge muffler <NUM> are pressed onto the discharge side 530b of the valve plate <NUM>, wherein a first sealing element <NUM> is placed between the valve plate <NUM> and the suction connector head <NUM> as well as the discharge connector head <NUM> respectively.

During the suction cycle of the pump unit <NUM>, the piston <NUM> inside the cylinder <NUM> moves away from the valve plate <NUM>, so that a negative pressure builds up in the cylinder <NUM>, because the suction valve spring <NUM> keeps the suction opening <NUM> of the valve plate <NUM> closed due to its spring force, while the discharge valve spring <NUM> closes the discharge opening <NUM> of the valve plate <NUM>. When the negative pressure exceeds a certain threshold, the suction valve spring <NUM>, which at least has a section configured as a reed valve, opens the suction opening <NUM> to allow refrigerant to flow from the suction pipe <NUM> through the suction muffler <NUM> into the cylinder <NUM>.

During the compression cycle of the pump unit <NUM>, the piston <NUM> inside the cylinder <NUM> moves in the direction of the valve plate <NUM>, so that the refrigerant in the cylinder <NUM> is compressed, because the discharge valve spring <NUM> keeps the discharge opening <NUM> of the valve plate <NUM> closed due to its spring force, while the suction valve spring <NUM> keeps the suction opening <NUM> of the valve plate <NUM> closed. Once the pressure of the compressed refrigerant exceeds a predefined threshold, the discharge valve spring <NUM>, which is configured as a reed valve, opens the discharge opening <NUM> of the valve plate <NUM> to allow refrigerant to flow from the cylinder <NUM> through the discharge muffler <NUM> to the discharge tube <NUM>.

The suction muffler <NUM> includes a lower housing part <NUM>, an upper housing part <NUM> and an inner housing element <NUM>, which is inserted into a suction muffler volume <NUM> defined by the lower housing part <NUM> and the upper housing part <NUM> of the suction muffler <NUM>. Refrigerant is sucked into the suction muffler <NUM> via an inlet opening <NUM> located in the upper housing part <NUM> mainly during the suction cycle of the pump unit <NUM>. The suction muffler <NUM> dampens sound based on the well-known Helmholtz principle when refrigerant flows through it, i.e. by chambers formed within the suction muffler <NUM> which act as resonators that absorb sound. The refrigerant escapes the suction muffler <NUM> through the suction connector head <NUM>, which is placed above the suction opening <NUM> of the valve plate <NUM> and is located on the upper housing part <NUM> of the suction muffler <NUM>.

The discharge muffler <NUM> includes a lower housing part <NUM>, an upper housing part <NUM> and the discharge connector head <NUM>, which is connected to the upper housing part <NUM> of the discharge muffler <NUM>. During the discharge cycle of the pump unit <NUM>, compressed refrigerant coming from the discharge opening <NUM> of the valve plate <NUM> enters the discharge muffler <NUM> though the discharge connector head <NUM>. The discharge muffler <NUM> dampens sound based on the well-known Helmholtz principle when refrigerant flows through it, i.e. by chambers formed within the discharge muffler <NUM> which chambers act as resonators that absorb sound and or by pulsation filtering. The compressed refrigerant escapes the discharge muffler <NUM> through a discharge connection tube <NUM>, which is connected to the discharge tube <NUM> via connection sleeve <NUM> and an O-ring seal <NUM>.

The mounting of the cylinder head assembly <NUM> to the cylinder housing <NUM> is facilitated by a mounting assembly <NUM> (see <FIG>), which comprises a clamping element <NUM> for clamping the valve plate <NUM> to the valve plate seat <NUM> and a fixing element <NUM>, which presses the suction connector head <NUM> and the discharge connector head <NUM> onto the valve plate <NUM>. The fixing element <NUM> is latched onto the clamping element <NUM>. The clamping element <NUM> further comprises two positioning pins <NUM> (see <FIG>), which are used for aligning the discharge connector head <NUM> with the discharge opening <NUM> and the suction connector head <NUM> with the suction opening <NUM> respectively.

<FIG> shows the pump unit <NUM> of the refrigerant compressor <NUM> in an assembled state. The suction muffler <NUM> and the discharge muffler <NUM> are fixed to the cylinder housing <NUM> via the clamping element <NUM> and the fixing element <NUM> of the mounting assembly <NUM>, while the crankshaft <NUM> is inserted into the crankcase <NUM> and the stator <NUM> is surrounding the rotor <NUM>.

<FIG> shows a schematic rear view of an embodiment of the suction muffler <NUM> according to the invention from an angled top view, in which other main components of the cylinder head assembly <NUM> for connecting the suction muffler <NUM> with the cylinder housing <NUM> are presented in an exploded view. The suction muffler <NUM> comprises the lower housing part <NUM> having an outer surface 610b and the upper housing part <NUM> having an outer surface 620b. The lower housing part <NUM> has an outer tubular extension <NUM> with a diagonal cut at the bottom, which outer tubular extension <NUM> is surrounding an oil drain opening <NUM> (see <FIG>), which will be described in more detail below.

When assembled, a sealing surface 640a of the suction connector head <NUM> is pressed onto the discharge side 530b of the valve plate <NUM>, which faces in the opposite direction of the piston <NUM> (see <FIG>). The first sealing element <NUM> is placed between the valve plate <NUM> and the suction connector head <NUM>. The discharge valve spring <NUM> is located on a discharge side 530b of the valve plate <NUM>. On the suction side 530a of the valve plate <NUM>, which suction side 530a faces towards the piston <NUM> (see <FIG>), the cylinder gasket <NUM> and the suction valve spring <NUM> of the cylinder head assembly <NUM> are located.

As can be seen in detail in <FIG>, the valve plate <NUM> features the suction opening <NUM> for letting refrigerant flow from the suction muffler <NUM> into the cylinder <NUM>, when the suction valve spring <NUM> is opening the suction opening <NUM>. The valve plate <NUM> further features the discharge opening <NUM> for letting compressed refrigerant flow from the cylinder through the discharge muffler <NUM> to the discharge tube <NUM>, when the discharge valve spring <NUM> opens the discharge opening <NUM>. The suction opening <NUM> can be closed by a suction reed valve section <NUM> of the suction valve spring <NUM>.

The first sealing element <NUM> comprises a first sealing section 550a and a second sealing section 550b, wherein the first section 550a is essentially shaped as a flat gasket and the second section 550b has characteristics and a cross section similar to an O-ring seal. The first sealing element <NUM> further comprises a suction opening <NUM> in the first section 550a and a discharge opening <NUM> in the second section 550b. The suction opening <NUM> of the first sealing element <NUM> is arranged to essentially match with the suction opening <NUM> of the valve plate <NUM>, so that refrigerant can also pass the first sealing element <NUM>, when refrigerant is sucked through the suction muffler <NUM> into the cylinder <NUM>. When mounted, the fixing element <NUM> (see <FIG>) compresses the first sealing section 550a between the sealing surface 640a of the suction connector head <NUM> and the discharge side of the valve plate <NUM> in order to seal the low-pressure connection between the valve plate <NUM> and the suction connector head <NUM> in the region of the suction opening <NUM>. The second sealing section 550b is configured to be inserted into a circumferential groove of a sealing surface of the discharge connector head <NUM>. Accordingly the second sealing section 550b is designed to seal the high-pressure connection between the valve plate <NUM> and the discharge connector head <NUM> of the discharge muffler <NUM> in the region of the discharge opening <NUM>, when the fixing element <NUM> presses the discharge connector head <NUM> onto the valve plate <NUM>.

The suction connector head <NUM> has an outlet opening <NUM>, so that refrigerant can flow from the suction muffler <NUM> into the cylinder <NUM> during the suction cycle. The dimensions of the outlet opening <NUM> of the suction connector head <NUM> match those of the suction opening <NUM> of the first sealing element <NUM>, so that the sealing surface 640a presses the first sealing section 550a against the valve plate <NUM>.

As can be seen in <FIG> the suction connector head <NUM> has two first positioning openings <NUM>, with which the suction muffler <NUM> is positioned on the positioning pins <NUM> of the clamping element <NUM>, when assembled (see <FIG>).

<FIG> shows a schematic front view of the suction muffler <NUM> from an angled top view.

In this front view the inlet opening <NUM>, which is located in the upper housing part <NUM> and connected to the interior inlet tube <NUM>, is visible. Through the inlet opening <NUM> refrigerant is sucked into the suction muffler <NUM> mainly during the suction cycle of the pump unit <NUM>. The inlet opening <NUM> is surrounded by an embossing <NUM>, which embossing <NUM> is also located in a recessed area <NUM> on the outer surface 620b of the upper housing part <NUM>. As the inlet opening <NUM> is located in this recessed area <NUM> it is made possible that the embossing <NUM> does not extend over an enveloping surface of the suction muffler <NUM>, wherein the embossing <NUM> simultaneously can extend from the outer surface 620b of the upper housing part <NUM>.

The purpose of this embossing <NUM> is to prevent oil drops or droplets, which splash onto the suction muffler <NUM> during operation, from entering the suction muffler <NUM> through the inlet opening <NUM>. In case oil drops or droplets are formed in the area surrounding the inlet opening <NUM>, the embossing <NUM> forms an obstacle so that the fluid oil cannot enter the suction muffler <NUM>, and on the other hand the embossing <NUM> serves to make the oil flow down along the embossing <NUM> by gravitational force and/or vibration of the pump unit <NUM>. To better direct the oil downwards, two tangential extensions 623a are provided. The tangential extensions 623a are positioned symmetrical to a vertical symmetry plane of the inlet opening <NUM> and are originating from the outmost points of the inlet opening <NUM> in relation to said vertical symmetry plane.

In <FIG> the lower housing part <NUM> of the suction muffler <NUM> of <FIG> and the inner housing element <NUM> arranged therein is presented.

The lower housing part <NUM> has a circumferential fixing groove <NUM> to receive a circumferential fixing protrusion <NUM> of the upper housing part <NUM> of the suction muffler <NUM> (see e.g. <FIG>). The circumferential fixing protrusion <NUM> and the circumferential fixing groove <NUM> are welded together during production of the suction muffler <NUM>. The circumferential fixing groove <NUM> is formed by a first wall section <NUM> and a second wall section <NUM> of the lower housing part <NUM> spaced apart from the first wall section <NUM> (compare <FIG>). The second wall section <NUM> projects over the first wall section <NUM> and thereby forms an upper edge <NUM> of the lower housing part <NUM>. Further, the outer tubular extension <NUM> protrudes from a bottom section of the lower housing part <NUM> downwards in the direction opposite of the inlet opening <NUM>.

The inner housing element <NUM> divides the suction muffler volume <NUM> (see <FIG>) into a first suction muffler chamber <NUM> and a second suction muffler chamber <NUM> (see also <FIG>). The first suction muffler chamber <NUM> is bounded by the lower housing part <NUM>, a top wall <NUM> of the inner housing element <NUM> and a side wall <NUM> of the inner housing element <NUM> (compare <FIG>). The inner housing element <NUM> is arranged in the lower housing part <NUM> in such a way that the top wall <NUM> of the inner housing element <NUM> is aligned with the upper edge <NUM> of the lower housing part <NUM> and is preferably oriented horizontally.

In order to be able to fix the inner housing element <NUM> in a stable manner inside the suction muffler <NUM> a plurality of reinforcement ribs <NUM> is provided, and one of which reinforcement ribs <NUM> can be seen in <FIG> (compare <FIG> and <FIG>).

The inner housing element <NUM> has a protruding tubular section <NUM> for fluidly connecting the first suction muffler chamber <NUM> with the second suction muffler chamber <NUM>, which tubular section <NUM> extends perpendicularly to both sides of the top wall <NUM> of the inner housing element <NUM> (see <FIG>). The protruding tubular section <NUM> has an annular cross section with a cylindrical inner surface and a cylindrical outer surface.

<FIG> shows a detailed view of the inner housing element <NUM> from the embodiment of <FIG>. The inner housing element <NUM> comprises the top wall <NUM> and the side wall <NUM> for dividing the muffler volume <NUM> into the first suction muffler chamber <NUM> and the second suction muffler chamber <NUM> (compare <FIG> and <FIG>). The side wall <NUM> has an oil opening <NUM> for allowing oil flow from one suction muffler chamber <NUM> to the other suction muffler chamber <NUM>, when assembled. The side wall <NUM> extends perpendicularly from the top wall <NUM>. Further, the contour of the top wall <NUM> corresponds with the contour of the second wall section <NUM> of the lower housing part <NUM> so that an edge portion of the top wall <NUM> abuts against the second wall section <NUM> of the lower housing part <NUM>, when assembled (see <FIG>).

Further the inner housing element <NUM> comprises the protruding tubular section <NUM>, which perpendicularly extends to both sides of the top wall <NUM> of the inner housing element <NUM>. Thereby the protruding tubular section <NUM> in other words forms a cylindrical tube, which penetrates the top wall <NUM>.

<FIG> shows a top view of the lower housing <NUM> of the suction muffler <NUM> according to the embodiments of <FIG>.

The lower housing part <NUM> has an inner surface 610a, which acts as a boundary for the first suction muffler chamber <NUM> and the second suction muffler chamber <NUM>. Furthermore, the outer surface 610b of the lower housing part <NUM> forming an outer contour of the can be seen. For fixing the lower housing part <NUM> to the upper housing part <NUM>, the lower housing part <NUM> has the circumferential fixing groove <NUM> as described previously.

Inside the lower housing part <NUM> of the suction muffler <NUM> the oil drain opening <NUM> is located, so that oil collecting on a bottom section of the inner surface 610a can drain from the suction muffler volume <NUM>.

Further, two sets of reinforcement ribs <NUM> are provided in the inside of the housing part <NUM>, which reinforcement ribs <NUM> protrude from the inner surface 610b of the lower housing part <NUM> an run parallel to the height direction. In each set, two reinforcement ribs <NUM> are spaced apart from each other in order to form a slot <NUM>. Further, the two sets of reinforcement ribs <NUM> are arranged opposite each other in such a manner, that the side wall <NUM> of the inner housing element <NUM> can be guided into the slots <NUM>. The slots <NUM> are designed to support opposite edges of the side wall <NUM> of the inner housing element <NUM>.

<FIG> shows a bottom view of the upper housing element <NUM> of the suction muffler <NUM>.

The upper housing part <NUM> has an inner surface 620a, which acts as a boundary for the first suction muffler chamber <NUM> and the second suction muffler chamber <NUM>. Furthermore, the outer surface 620b forming an outer contour of the upper housing part <NUM> can be seen. For fixing the upper housing part <NUM> to the lower housing part <NUM>, the upper housing part <NUM> has the circumferential fixing protrusion <NUM> described before. The circumferential fixing protrusion <NUM> perfectly fits into the circumferential fixing groove <NUM> of the lower housing part <NUM>, when assembled. Inside the upper housing part <NUM> the inlet tube <NUM> for directing refrigerant to the first suction muffler chamber is provided, which is connected to the inlet opening <NUM> (see <FIG>). Further, an outlet tube <NUM> is located within the upper housing part <NUM>, which connects the second suction muffler chamber <NUM> with the outlet opening <NUM> of the suction connector head <NUM>.

<FIG> shows a sectional view of a side view of the suction muffler <NUM>, wherein the sectional plane is the vertical symmetry plane of the inlet opening <NUM>.

The suction muffler <NUM> according to the present embodiment consists of the lower housing part <NUM> and the upper housing part <NUM>, which together form the suction muffler housing <NUM>. As can be seen in detail, the circumferential fixing protrusion <NUM> of the upper housing part <NUM> fits into the circumferential fixing groove <NUM> of the lower housing part <NUM> to adjoin the muffler housing <NUM>, wherein the upper housing part <NUM> and the lower housing part <NUM> are welded together.

The inner housing element <NUM>, which is inserted into the muffler volume <NUM> enclosed by the muffler housing <NUM>, divides the suction muffler volume <NUM> into the first suction muffler chamber <NUM> and the second suction muffler housing <NUM> by means of the top wall <NUM> and the side wall <NUM> as described before.

Inside the suction muffler <NUM> the inlet tube <NUM> is provided, which is connected to the inlet opening <NUM> located in the upper housing part <NUM>. An end section of the inlet tube <NUM> is extends into the protruding tubular extension <NUM> of the inner housing element <NUM> in such a manner that an air gap <NUM> is formed. Refrigerant can flow from the inlet opening <NUM> through the inlet tube <NUM> into the first suction muffler chamber <NUM>. The tubular section <NUM> of the inner housing element <NUM> and the inlet tube have longitudinal axes which are oriented in parallel.

Refrigerant can therefore enter the suction muffler <NUM> via the inlet opening <NUM> and is directed into the first suction muffler chamber <NUM> by the inlet tube <NUM>. Afterwards the refrigerant can flow from the first suction muffler chamber <NUM> into the second suction muffler chamber <NUM> via the air gap <NUM> formed between an outer surface of the inlet tube <NUM> and an inner surface of the protruding tubular section <NUM>. Furthermore, it can be seen that the inner housing element <NUM>, the inlet tube <NUM> and the outlet tube <NUM> are surrounded by the muffler housing <NUM> and contained within the suction muffler volume <NUM>.

<FIG> shows a further, partially offset sectional view the suction muffler <NUM>. The first sectional plate incorporates a first longitudinal axis of the protruding tubular section <NUM> of the inner housing element <NUM> and a second longitudinal axis of the outlet tube <NUM>. The second sectional plane is intersecting with the first sectional plane and runs in direction of a lateral end section of the suction muffler housing <NUM>.

An inlet section <NUM> of the suction muffler <NUM> comprises the inlet opening <NUM>, which is connected to the inlet tube <NUM>. Preferably the inlet tube <NUM> is integrally formed with the upper housing part <NUM>. Via the inlet section <NUM> refrigerant can enter the suction muffler <NUM> as described in detail before.

An outlet section <NUM> of the suction muffler <NUM> comprises the suction connector head <NUM>, the outlet opening <NUM> and the outlet tube <NUM>. Via outlet section <NUM> refrigerant can leave the suction muffler <NUM> as described in detail before.

It is apparent from synopsis of <FIG> and <FIG> with the previously discussed figures that the inner housing element <NUM> divides the suction muffler volume <NUM> into the first suction muffler chamber <NUM> and the second suction muffler chamber <NUM> by means of the top wall <NUM> and the side wall <NUM>. Lateral edge portions of the side wall <NUM> of the inner housing element <NUM> are arranged in the slots <NUM> between two reinforcement ribs <NUM> and are supported the reinforcement ribs <NUM> forming the slots. The side wall <NUM> comprises the oil opening <NUM> for allowing oil from the second suction muffler chamber <NUM>, which has not oil drain opening, to flow to the oil drain opening <NUM> located in the first suction muffler chamber <NUM>. Thus, the first suction muffler chamber <NUM> and the second suction muffler chamber <NUM> are also connected via oil opening <NUM>. However, oil that accumulates within the first suction muffler chamber <NUM> within the region of the oil drain opening <NUM> during operation will close the oil opening <NUM> in the side wall as well as the oil drain opening <NUM>.

As can be seen, the oil drain opening <NUM> is located on the bottom of the lower housing part <NUM>, wherein the inner surface 610a is declining towards the oil drain opening <NUM> at least in sections adjacent to the oil drain opening <NUM>. As a result of this design the oil drain opening <NUM> is located at the lowest point of the lower housing part <NUM>. Oil can drain through the oil drain opening <NUM> and drips from the oil drain opening <NUM> by trickling along an inner surface of the outer tubular extension <NUM>. On the diagonal cut end section, preferably a <NUM>° angled diagonal cut, of the outer tubular extension <NUM>, droplets are forming from the oil draining from the oil drain opening <NUM>.

Claim 1:
A suction muffler (<NUM>) for an encapsulated refrigerant compressor (<NUM>), comprising
- a suction muffler housing (<NUM>) defining a suction muffler volume (<NUM>), wherein the suction muffler housing (<NUM>) is made of plastic material, wherein the suction muffler housing (<NUM>) has a lower housing part (<NUM>) and an upper housing part (<NUM>);
wherein the upper housing part (<NUM>) includes
- an inlet section (<NUM>) to allow refrigerant to enter the suction muffler volume (<NUM>), the inlet section (<NUM>) comprising an inlet opening (<NUM>) and an inlet tube (<NUM>) for directing refrigerant to a first suction muffler chamber (<NUM>), the inlet opening (<NUM>) being connected to the inlet tube (<NUM>) and
- an outlet section (<NUM>) to allow refrigerant to escape from the suction muffler volume (<NUM>) of the suction muffler (<NUM>) towards the cylinder (<NUM>) of the refrigerant compressor (<NUM>);
wherein the lower housing part (<NUM>) includes an oil drain opening (<NUM>);
the suction muffler (<NUM>) further comprises an inner housing element (<NUM>), which is inserted into the suction muffler housing (<NUM>), which inner housing element (<NUM>) separates the suction muffler volume (<NUM>) into the first suction muffler chamber (<NUM>) and a second suction muffler chamber (<NUM>),
characterized in that
the inner housing element (<NUM>) comprises a top wall (<NUM>) and a side wall (<NUM>),
wherein the first suction muffler chamber (<NUM>) is bounded by the lower housing part (<NUM>), the top wall (<NUM>) of the inner housing element (<NUM>) and the side wall (<NUM>) of the inner housing element (<NUM>),
and wherein the top wall (<NUM>) has a protruding tubular section (<NUM>), wherein at least a section of the inlet tube (<NUM>) is received by the protruding tubular section (<NUM>) of the inner housing element (<NUM>).