JP6738347B2 - Reciprocating compressor for cooling device - Google Patents

Description

The present invention relates to a reciprocating compressor for a cooling device.

The reciprocating compressor of the present invention includes a closed circuit having a main branch portion and at least one secondary economizer branch portion, and is used in a cooling device in which a predetermined amount of refrigerant circulates. At the branch portion of the closed circuit, all the refrigerant circulates at two predetermined distribution flow rates and is discharged from the compressor. Such a secondary economizer branch is, on the one hand, fluidly connected to a section of the closed circuit contained between the condenser and the expansion valve, and on the other hand the distribution flow through the secondary branch to the compressor. It is fluidly connected to the cylinder of the reciprocating compressor for reinjection. As is known, a condenser, expansion valve, evaporator, and reciprocating compressor are fluidly connected to each other along a closed circuit. As is further known, the distribution flow of refrigerant through the secondary economizer branch, which may include an additional expansion valve and a heat exchanger, or an additional evaporator, results in a maximum and minimum pressure in the chiller circuit. Has a pressure intermediate to that of the fluid to the condenser and the pressure of the fluid to the evaporator along the main branch.

In general, in compressors commonly used in refrigeration systems, the exact position of the compressor into which the aforementioned distribution flow coming from the secondary economizer branch is injected is always determined. For example, in screw compressors, which are known by known law to increase in pressure in the direction of the compressor axis, the exact injection point of the dispensed flow coming from the secondary economizer branch can be found. The same is true for other types of compressors such as screw compressors and scroll compressors. Although the operating principle and pressure distribution in the compression chamber are different from those in the screw compressor, the scroll compressor can always know the pressure at any point in the compression chamber.

When a reciprocating compressor including a cylinder and a piston that reciprocates in the cylinder is used, the pressure changes with the passage of time, and in the suction and compression strokes, the cylinder as a whole, regardless of the position of the piston in the cylinder, Always substantially the same.

However, in a cooling device having a reciprocating compressor, in order to make it possible to use a secondary economizer branch, Patent Document 1 by Emerson Climate Technologies Inc. In addition to having a general suction duct arranged, use a cylinder provided with side suction holes with a circular cross section for the inflow of the distribution flow coming from the economizer branch described above at a defined intermediate pressure. Is described. A valve, the opening and closing of which is synchronized with the drive shaft of the compressor, is arranged in a suction hole of a cylinder of the compressor through a complicated mechanism including at least one cam and at least one follower. ing. Thereby, the distribution flow rate of the above-mentioned refrigerant from the secondary economizer branch portion can be injected only immediately before the pressure of the piston reaches a pressure slightly lower than the pressure of the above-mentioned secondary distribution flow rate.

Another solution is being investigated in order to avoid having to use a complicated synchronization system as described in US Pat. In particular, U.S. Pat. No. 5,837,049 to Carrier Company describes how to provide a compressor cylinder with a circular suction hole that is exposed by the piston during the suction stroke and is covered by the piston during the compression stroke of the piston. Has been. For reciprocating compressors with the same displacement, part of the piston stroke is used to allow the inflow of the distribution flow of refrigerant from the secondary economizer bifurcation, so if there are no lateral holes, the compressor Unfortunately, the work that can be done is significantly reduced. It is very difficult to use a compressor with the same amount of displacement as that used in a cooling device without a secondary economizer branch, especially if the distribution flow rate is considerably high to be 50% of the total flow rate. .. In fact, in such a case, the suction holes for the refrigerant liquid would be significantly longer in the axial direction of the cylinder and thus would have a larger displacement than would normally be used, thus reducing the overall cost. You will have to use a large compressor.

U.S. Patent Application Publication No. 2014/0170003 International Publication No. 2007/064321

Therefore, the object of the present invention is that it can be used in a cooling device provided with at least one secondary economizer branch, the performance is the same, more than a reciprocating compressor used in a conventional cooling device, The object is to provide a reciprocating compressor having a small displacement amount.

A further object of the invention is, in addition to achieving the above mentioned objects, to provide a reciprocating compressor which is very simple to implement even when starting from known compressors without lateral holes.

The above object and other objects are achieved by a reciprocating compressor for a cooling device, which is provided with a closed circuit according to the present invention, wherein the closed circuit is a main recirculation refrigerant of a first flow rate flowing into the compressor. A branch portion and at least one secondary economizer branch portion in which a second flow rate refrigerant circulates at a pressure different from the pressure of the first flow rate refrigerant, and the compressor has at least one cylinder; And at least one piston reciprocating in the at least one cylinder between top dead center and bottom dead center, the compressor comprising at least one piston for inflow of the first flow rate of refrigerant. A suction duct and at least one first suction hole provided in the wall of the cylinder for inflow of the second flow rate of the refrigerant are provided, and the piston has at least the first suction hole in its suction stroke. At least partially exposed therein and covering the first suction hole at least during its compression stroke, the first suction hole having a slit shape with a main dimension substantially transverse to the axis of the cylinder. Characterize.

In fact, a long main dimension slit-shaped first suction hole that substantially traverses the axis of the cylinder does not significantly affect the displacement dimension of the compressor itself, and allows a large amount of flow from the secondary economizer branch. Allows the refrigerant to flow. In fact, the dimensions of the slit are very limited along the axial direction of the cylinder, i.e. in height, but significantly larger across the cylinder axis, i.e. in length. In this way, a large amount of refrigerant can flow into the cylinder in the same very short time as the piston stroke for opening and closing the side holes.

The term slit refers to a notch of any shape formed in the wall of a cylinder and having a predominant dimension (also referred to as the main dimension) with respect to other dimensions. In particular, in this example, the major or dominant or more relevant dimension is the dimension lying in a plane transverse to the compressor cylinder axis and parallel to the compressor cylinder axis, i.e. the slit height. It is not the dimension in the depth direction.

According to an embodiment disclosed herein, the first suction hole is arranged next to the bottom dead center of the piston, preferably the first suction hole is aligned with the bottom dead center of the piston. It has a lower side that is substantially coplanar. Such a solution makes it possible at the same time to avoid the displacement of the compressor in the suction and compression strokes in the lateral holes and the undue loss of compression work.

According to the invention, the at least one closed circuit of the cooling device further comprises at least one additional secondary economizer branch in which an additional flow of refrigerant circulates, the compressor being the addition in the compressor. Further comprising at least one second suction hole provided in the wall of the cylinder for the inflow of a flow rate of the refrigerant, wherein the second suction hole has a main dimension substantially transverse to the axis of the cylinder. Has a slit shape and is arranged at a distance further from the bottom dead center than the distance at which the first suction hole is located, and the piston exposes the second suction hole at least during its suction stroke. And cover the second suction hole at least during the compression stroke. The additional flow rate coming from the additional secondary economizer branch flows into the cylinder of the compressor through the second suction hole at a pressure lower than the pressure of the second flow rate coming from the secondary economizer branch section. In such a case, such a configuration is particularly suitable.

According to embodiments disclosed herein, the first suction hole and the second suction hole, both having a slit shape, are substantially or generally rectangular, i.e. facing the inner surface of the cylinder of the compressor. The slit surface is substantially rectangular on the inner cylinder surface of the compressor cylinder. Substantially rectangular shapes whose top or bottom dimension is significantly larger than the height of the two sides, ie the dimension along the axial direction of the compressor cylinder, have sides which are fused together, i.e. sharp. It is also possible to have a substantially rectangular surface profile on the inner surface of the cylinder without edges.

Further, the ratio of the dimension in the height direction of the first suction hole and/or the second suction hole to the length, that is, the dimension along the main direction is smaller than 0.5, preferably 0.2. Smaller than In fact, Applicants have tested and such dimensions have been found to give the best performance. It should be noted that the length of the slit is calculated along the arc of the cylinder through which the slit extends so that it passes through the center of the height of the slit on a plane transverse to the axis of the cylinder.

In addition, the lower edge of the second suction hole is flush with the upper edge of the first suction hole.

According to a further embodiment, the first suction hole and/or the second suction hole comprises at least one non-return valve operatively connected. This check valve prevents the refrigerant flowing back into the compressor through the first and second suction holes from flowing backward during the piston ascending step, that is, the refrigerant compressing step.

More specifically, the check valve is a deformable reed type and is housed in the wall of the cylinder. This makes the compressor more compact, eliminating the need for complex elements to synchronize the opening and closing of the side holes.

It is a schematic diagram of the cooling device provided with the reciprocating compressor by this invention. It is a PH line diagram of the refrigerating cycle regarding the refrigerating device of FIG. It is a typical longitudinal section inside a cylinder of a compressor in a suction and compression step. It is a typical longitudinal section inside a cylinder of a compressor in a suction and compression step. It is a typical longitudinal section inside a cylinder of a compressor in a suction and compression step. It is a typical longitudinal section inside a cylinder of a compressor in a suction and compression step. FIG. 3 is a vertical cross-sectional view of a cylinder of a reciprocating compressor according to the present invention, showing first and second suction holes provided in the wall of the cylinder of the compressor. FIG. 3 is a cross-sectional view of a cylinder of a reciprocating compressor according to the present invention showing first and second suction holes provided in the wall of the cylinder of the compressor. It is a schematic diagram of another cooling device provided with the reciprocating compressor by this invention. FIG. 6 is a PH diagram of a refrigeration cycle relating to the cooling device of FIG. 5.

For purposes of illustration only, and without limitation, some specific embodiments of the present invention are described below with reference to the accompanying drawings.

In each figure, reference numeral 100 indicates a reciprocating compressor according to the present invention.

FIG. 1 shows a reciprocating compressor 100 according to the present invention comprising a cylinder 110 and a piston 111 which reciprocates in a cylinder 110 between a top dead center S (see FIG. 3d) and a bottom dead center I (see FIG. 3c). It is a schematic diagram of the cooling device 200 provided with. In particular, the cooling device 200 includes a closed circuit C in which a certain amount of refrigerant circulates. This closed circuit C includes, in that order, a main branch portion M in which a refrigerant having a first flow rate X circulates and flows into the reciprocating compressor 100 through a suction duct 109, a first secondary branch portion E, and a second branch portion E. And a secondary branch E′. In the first secondary branch E, the second flow rate X1 of the refrigerant circulates, and in the additional secondary branch E', the additional flow rate X2 of the refrigerant circulates. The sum of the flow rates circulating in the main branch section M and the two secondary branch sections E and E′ is the flow rate flowing out of the reciprocating compressor 100 through the closed circuit C.

As shown in FIG. 1, the cooling device 200 further includes a condenser 101, a first expansion valve 102, and a first evaporator 103. Both the first expansion valve 102 and the first evaporator 103 are arranged along the main branch M of the closed circuit C in which the flow rate X circulates. The flow rate X is given by the difference between the total flow rate that circulates in the closed circuit C and the flow rates X1 and X2 that circulate in the two secondary branches E and E′, and the suction on the upper surface of the cylinder 110 of the reciprocating compressor 100. It enters the reciprocating compressor 100 directly through the duct 109 (see FIG. 3a).

The two secondary branches E and E'include a second expansion valve 130, 130' and a second evaporator 140, 140', respectively. In each of the secondary branches E and E', all values of the circulation flow rate, pressure and temperature are different. This type of configuration allows the cooling device 200 to cool three different chambers connected to each evaporator 103, 140, 140'. In particular, the second flow rate X1 and the additional flow rate X2 circulating along the secondary branch E and the additional secondary branch E', respectively, are at different temperatures and pressures. The pressure of the flow rate X1 that circulates along the secondary branch E is intermediate between the pressure of the fluid in the condenser 101 and the pressure in the first evaporator 103, and the additional secondary branch E′ is circulated. The pressure of the additional flow rate X2 of the refrigerant is intermediate between the pressure of the fluid of the first flow rate X and the pressure of the fluid of the second flow rate X1.

Note that in FIG. 1, the thermodynamic states of the refrigerant circulating in the closed circuit C of the cooling device 200 are indicated in parentheses by the numbers 1-8. 2, the thermodynamic cycle performed by the refrigerant in the cooling device 200 is shown, together with information on the thermodynamic state of the fluid at corresponding points in the closed circuit C. The numbers 9 and 10 shown in the graph of FIG. 2 indicate the openings of the second suction hole 112 and the first suction hole 107 provided in the wall 110a of the cylinder 110 of the reciprocating compressor 100, as will be described later. Corresponds to the thermodynamic state of the refrigerant in the compressor 100 during the suction step (FIGS. 3b and 3c).

FIG. 5 shows an additional cooling device 200' comprising a reciprocating compressor 100 similar to one of the embodiments shown in FIG.

The cooling device 200′ includes a main branch M in which a refrigerant of a first flow rate X circulates at a predetermined pressure, a first condenser 101, a first evaporator 103, a first condenser 101 and a first condenser 101. A closed circuit C having a first expansion valve 102 arranged between one evaporator 103 is provided. The closed circuit C also includes a first economizer branch E in which the refrigerant having the second flow rate X1 circulates. The first economizer branch E is fluidly connected to the reciprocating compressor 100 and a section 106 of the closed circuit C included between the first condenser 101 and the first expansion valve 102.

In the embodiments disclosed herein, the closed circuit C further comprises an additional economizer branch E'for an additional flow rate X2 of refrigerant.

According to the embodiments disclosed herein, the economizer branch E, and the additional secondary economizer branch E'include a second expansion valve 150, 150', a first condenser 101 and a first condenser 101 and a first expansion valve. It comprises at least one heat exchanger 160, 160' with a section 106 of the closed circuit C contained between the expansion valves 102.

According to the embodiments disclosed herein, the second flow rate X1 is the pressure P ₂ of the condenser and the suction pressure of the cylinder 110 in the cylinder 110 of the reciprocating compressor 100, that is, the suction step of the reciprocating compressor 100. In the above, the suction pressure P ₈ is intermediate to the pressure P ₁ of the fluid having the flow rate X flowing from the suction duct 109 into the cylinder 110 of the compressor.

Note that in FIG. 5, the thermodynamic states of the refrigerant circulating in the closed circuit C of the cooling device 200' are indicated in parentheses by the numbers 1-10. Next, in FIG. 6, the thermodynamic cycle performed by the refrigerant in the closed circuit C is shown, together with information on the respective thermodynamic conditions of the refrigerant. Reference numerals 11 and 12 shown in the graph of FIG. 6 denote suction at the openings of the second suction hole 112 and the first suction hole 107 in the wall 110 a of the cylinder 110 of the reciprocating compressor 100, as described later. The steps (FIGS. 3b and 3c) correspond to the thermodynamic state of the refrigerant in the compressor 100.

According to the present invention, in both the cooling devices 200, 200′, the reciprocating compressor 100 has a first suction hole provided in the wall 110a of the cylinder 110 for the inflow of the above-mentioned second flow rate X1 of the refrigerant. It is equipped with 107.

The reciprocating compressor 100 further includes a second suction hole 112 for the inflow of the refrigerant having the additional flow rate X2. More specifically, the second suction hole 112 is arranged at a distance D from the bottom dead center I of the piston 111, which is larger than the distance d at which the first suction hole 107 is located. This distance is assigned to two planes P and P1 which intersect the axis A of the cylinder 110 and pass through the center of the height H of the suction holes 107 and 112.

According to the embodiments disclosed herein, the first suction hole 107 for the second flow rate X1 of the refrigerant (R404a in this example) is a slit and is located at the bottom dead center I of the piston 111. The piston exposes the first suction hole 107 during the suction stroke and covers the first suction hole 107 during the compression stroke. Further, as described above, the second flow-in refrigerant for the inflow of the additional flow amount X2 arranged at the distance D from the bottom dead center I of the piston 111, which is further away than the distance d at which the first suction hole 107 is located, is provided. The suction hole 112 is also a slit. Also, the second slit 112 is arranged in the wall 110a of the cylinder, and the piston exposes the second suction hole 112 before exposing the first suction hole 107 during the suction stroke of the piston. The second suction hole 112 is covered during the compression stroke after the suction hole 107 has been covered.

In particular, both the first suction hole 107 and the second suction hole 112 are provided with a slit whose main dimension L substantially intersects the axis A of the cylinder 110. In particular, the slit is on the inner surface 110c of the cylinder 110 and has a substantially rectangular surface along the arc of the cylinder 110. More specifically, for example, such a surface forms the wall 110a of the cylinder 110 in a state where the rotation axis of the milling machine is parallel to the axis A of the cylinder 110 and the front direction of the milling machine is orthogonal to the axis of the cylinder 110. Obtained by cutting with a milling machine. Thus, the surfaces thus obtained are fused to one another and are substantially rectangular, even though the rectangular sides are not connected to each other by sharp edges. Preferably, the ratio of height H to length L (which is also the primary dimension) is 0.2. Here, the length is measured along the arc drawn by the slit along the inner surface of the cylinder 110c (see especially the dotted line shown in FIG. 4b). In particular, the length L must be measured on the plane P or P1 which intersects the axis A of the cylinder and passes through the middle of the height H of the respective slits.

In any case, it should be noted that any slit having a dimensional ratio of height H to length L of less than 0.5 is still within the protection scope of the present invention. Further, it should be noted that the slit, ie the surface extending to the inner surface 110c of the cylinder 110, follows the shape of the wall 110a of the cylinder 110 itself, so that the lower side and the upper side merge on each connecting side.

In particular, as shown in FIGS. 3a to 3d, the first suction hole 107 has a lower side 107a that is substantially flush with the bottom dead center I of the piston 111. More specifically, the lower side 112a of the second suction hole 112 is flush with the upper side 107b of the first suction hole 107.

According to the embodiment shown in Figures 3a to 3d, only the second suction hole 112 is provided with a non-return valve 180 functionally coupled. Here, in the embodiment shown in FIGS. 4a and 4b, both the first suction hole 107 and the second suction hole 112 are provided with a deformable reed-type check valve 180.

The check valve 180 is dimensioned to deform only when a predetermined pressure is exceeded. Moreover, the check valve 180 is housed in the wall 110 a of the cylinder 110 of the first condenser 101. In the undeformed state, the check valve 180 abuts on the pair of protrusions 190 and 191 that come into contact with the outer surface 110b of the cylinder 110.

A reciprocating compressor 100 provided with a first suction hole 107 and a second suction hole 112, and thus a cooling device 200 or 200 provided with a secondary economizer branch E and an additional secondary economizer branch E′. ', the solution when the reciprocating compressor 100 is provided with at least one first suction hole 107 but not at least one second suction hole 112, and It should be mentioned that the cooling device 200 or 200' provided with only the secondary economizer branch E is still within the protection scope of the present invention. In this case, the first flow rate entering the reciprocating compressor 100 through the suction duct 109 is given by the difference between the total flow rate circulating in the closed circuit C and the unique second flow rate X1.

The operation of the reciprocating compressor 100 in the two cooling devices 200, 200' described respectively in Figures 1 and 5 is illustrated in Figures 3a to 3d. In fact, during the compressor suction step, ie when the piston 111 of the compressor 100 descends from top dead center S to bottom dead center I, the suction valve 113 of the compressor 100 passes from the main circuit M through the suction duct 109. It is open to receive the incoming fluid flow rate X (see Figure 3a). Subsequently, the piston 111 exposes the second suction hole 112, from which the additional flow rate X2 of refrigerant coming from the additional secondary economizer branch E'flows. Then, the suction valve is closed due to the increase in pressure. The pressure of such an additional flow X2 of refrigerant is higher than the pressure in the cylinder 110, so that the pressure rises inside the cylinder 110 (thermodynamic state 9 or depending on the cooling device 200 or 200'). 11). Of course, the check valve 180 remains open during such a step (see Figure 3b).

The piston then exposes the first suction hole 107, allowing a second flow rate X1 of refrigerant coming from the secondary economizer branch E to enter the cylinder 110. Of course, the pressure of the second flow rate X1 of the refrigerant coming from the secondary economizer branch E is higher than the pressure of the additional flow rate X2 of the refrigerant and the suction pressure. In any case, due to the mixing with the second flow rate X1, the pressure in the cylinder 110 of the compressor 100 rises before the compressor 100 starts the compression stroke (in the cooling device 200, the thermodynamic state 10, Thermodynamic state 12) in the cooling device 200'. Then, the piston 111 rises again and compresses the fluid in the cylinder 110 until the top dead center S is reached. When the pressure in the cylinder exceeds the condensing pressure, the exhaust valve 114 starts to open. During the rise of the piston 111, the check valve 180 arranged on the wall 110a of the cylinder 110 remains closed when the pressure in the cylinder 110 exceeds the pressure of the additional flow X2 coming from the additional secondary economizer branch E'. It must be noted that there is.

Finally, the mounting of the first suction hole 107 and/or the second suction hole 112 is carried out by easy milling or similar technical machining of the cylinder 110 along a plane transverse to the axis A of the cylinder 110 itself. It is preferable. Thereby, the cylinder of the existing reciprocating compressor having no through side hole can be converted by the easy milling of the cylinder 110. In this way, the cylinder is converted so that it is possible to operate a cooling device with at least one secondary economizer branch without having to perform complicated machining on the cylinder from a technical point of view or economically. You can

100 reciprocating compressor 101 first condenser 102 first expansion valve 103 first evaporator 106 section 107 first suction hole 107a lower side 107b upper side 109 suction duct 110 cylinder 110a wall 110b outer surface 110c inner surface 111 piston 112 second 2 Inlet hole 112a Lower side 113 Inlet valve 114 Exhaust valve 130,130' Second expansion valve 140,140' Second evaporator 150,150' Second expansion valve 160,160' Heat exchanger 180 Check Valve 190,191 Protrusion 200 Cooling device A Cylinder axis C Closed circuit E, E'Secondary economizer branch I Bottom dead center M Main circuit S Top dead center X1 First flow rate X2 Second flow rate

Claims (8)

A reciprocating compressor (100) for a cooling device (200) provided with a closed circuit (C), wherein the closed circuit is a main unit in which a refrigerant of a first flow rate (X) circulates and flows into the compressor. A branch (M), at least one secondary economizer branch (E) in which the fluid of the second flow rate (X1) circulates at a pressure different from the pressure of the refrigerant of said first flow rate (X), and an additional At least one additional secondary economizer branch (E') in which a refrigerant of flow rate (X2) circulates,
The compressor has at least one cylinder (110) and at least one piston (111) reciprocating in the at least one cylinder between a top dead center (S) and a bottom dead center (I). Is provided,
The compressor has at least one suction duct for the inflow of the first flow rate of refrigerant and at least one first suction duct provided on the wall of the cylinder for the inflow of the second flow rate of refrigerant. With a hole (107),
The piston at least partially exposes the first suction hole (107) during its suction stroke and covers the first suction hole at least during its compression stroke,
Here, the first suction hole (107) has a slit shape having a dimension (L) that substantially intersects the axis (A) of the cylinder, and is disposed at the bottom dead center of the piston.
The compressor further comprises at least one second suction hole (112) provided in the wall of the cylinder for inflow of the additional flow rate (X2) of refrigerant in the compressor,
Here, the second suction hole (112) has a slit shape having a dimension (L) substantially crossing the axis (A) of the cylinder, and the first suction hole (107) is formed from the bottom dead center. ) Is arranged at a distance (D) farther than the distance (d) at which
The cooling device is characterized in that the piston exposes the second suction hole (112) at least during its suction stroke and covers the second suction hole at least during its compression stroke. Reciprocating compressor (100) for 200). The reciprocating compressor (100) of claim 1, wherein the first suction hole has a lower side (107a) that is substantially flush with a bottom dead center of the piston. The said 1st suction hole and/or said 2nd suction hole have a substantially rectangular shape located in the cylindrical inner surface (110c) of the said cylinder (110), The claim 1 or 2 characterized by the above-mentioned. Reciprocating compressor described (100) The ratio of the height (H) to the length (L) of the first suction hole and/or the second suction hole is less than 0.5, preferably less than 0.2. Item 3. The reciprocating compressor (100) according to Item 3. The lower side (112a) of the second suction hole is flush with the upper side (107b) of the first suction hole (107) according to any one of claims 1 to 4. Reciprocating compressor (100) as described. The first suction hole (107) and/or the second suction hole (112) comprises at least one operatively coupled check valve (180). The reciprocating compressor (100) according to any one of items 1 to 5. The reciprocating compressor (100) according to claim 6, wherein the check valve is a deformable reed type. The reciprocating compressor (100) of claim 7, wherein the check valve is housed in a wall (110a) of the cylinder (110).

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