Patent Application
20180180064
The invention relates to an ejector arrangement comprising a housing and at least two ejectors arranged in said housing, wherein each ejector has a motive inlet, a suction inlet, an outlet, and a valve element.
An ejector arrangement of this kind is for example known from JP 2010-014353 A. Therein a plurality of ejectors is arranged in parallel in a refrigeration cycle.
In refrigeration systems ejectors are used as a pump to increase the pressure of a fluid coming from the suction inlet. Ejectors (sometimes also called injectors) to this end use the Venturi effect to increase the pressure coming from the suction inlet by providing a high pressure motive fluid supplied by the motive inlet.
Depending on the requirements of the refrigeration system it may be necessary to have a large capacity of fluid per time provided by the ejectors. On the other hand, a single ejector has a limited capacity for high pressure fluid that can be provided at the outlet. For example, from the above JP 2010-014353 A it is therefore known to use several ejectors in parallel.
However, the above solution only works optimal if the refrigerant system runs at full capacity. While one may provide each ejector with control means for individual adjustment of the opening degree in order to adjust the total amount of fluid provided by the ejectors at the outlet, this complicates the construction of the ejector arrangement and therefore increases the costs of the refrigeration system.
The object of the present invention therefore is to provide an ejector arrangement that allows to control the mass flow of fluid through the ejector arrangement while keeping the construction simple.
According to the present invention the above object is solved in that the ejector arrangement comprises a common actuator that is arranged to engage at least two of the valve elements to open the motive inlets.
With this solution the ejectors can all be opened between 0% and 100% allowing a good control of the mass flow of fluid through the ejectors. At the same time a common actuator for engaging and displacing the valve elements to open the individual motive inlets of the ejectors keeps the construction simple. The common actuator can be arranged to engage all of the valve elements at the same time or successively to open the motive inlets when the common actuator is displaced.
In a preferred embodiment the common actuator engages at least one of the valve elements before another valve element when the common actuator is displaced along a common axis. The common actuator may thus lift the individual valve elements to open the individual motive inlets one after another. This allows to gain a more gradual control of the mass flow of fluid through the whole injector arrangement. It is also possible that the common actuator engages two or more valve elements at the same time before engaging the next two or more valve elements.
In a further preferred embodiment each ejector is provided with a check valve or non-return valve at the suction inlet. Such a check valve or non-return valve may for example be a completely pressure controlled ball-valve or a ball-valve with a biasing member. This solution ensures that there is no risk of medium coming from the motive inlet flowing in the reverse direction through the suction inlet.
In a further preferred embodiment the housing comprises a cylindrical body around a common axis and the ejectors are arranged on a circular path around the common axis. This solution allows for a compact construction even if a large number of ejectors is used in the ejector arrangement. At the same time the construction may be kept simple because the common actuator may for example have a rotational symmetry around the common axis, in this case the cylinder axis of the cylindrical body of the housing.
Preferably at least one ejector has a larger flow capacity than the remaining ejectors. Preferably this ejector is the first ejector that is opened by the common actuator starting from the completely closed state of the ejector arrangement. This way, the ejector with the larger flow capacity is enabled to cope with the mixture of vapor and liquid that may typically be present during colder environmental conditions, e.g. during winter time. For example, the motive inlet with a larger flow capacity may have a motive inlet with a larger mean free flow cross section compared to the other motive inlets of the other ejectors. One may also chose the first two ejectors that are being opened by the common actuator to have a larger flow capacity than the remaining motive inlets of the other ejectors.
It is preferred that a common suction line is arranged in an end face of the housing connected to all suction inlets of the ejectors. This solution allows for a compact construction, in particular if the individual ejectors are sealed to the same end face of the common housing.
In a further preferred embodiment a common motive line connected to all motive inlets is arranged in the housing. The motive line may then for example be connected to a motive chamber in the housing. The valve elements may then block the flow of motive fluid from the motive line through the motive chamber and further through the motive inlets in the closed position of the valve elements.
It is preferred that when the common actuator is displaced towards an opening direction, the common actuator begins to open the next motive inlet only after the previously opened motive inlet is fully open. The individual ejectors are thus opened and activated one after another in such a way that only one ejector is being opened at a time while the common actuator is being displaced. All the other ejectors are either fully open or fully closed at the same time. This solution allows for a better proportional control of the mass flow through the ejector arrangement by controlling the common actuator.
It is preferred that when the common actuator is displaced towards an opening direction, the common actuator begins to open the next motive inlet before the previously opened motive inlet is fully open. This solution may be advantageous if the opening behavior of the individual ejectors near the fully open or fully closed position of the motive inlet is nonlinear. Consequently, one may still achieve a better proportional control of the whole ejector arrangement by controlling the common actuator.
It is preferred if at least two motive inlets are opened in parallel by the common actuator when the common actuator is displaced along the common axis. This solution is preferable if a large number of ejectors are used. It is however still possible that the common actuator always opens two, three, four or more motive inlets at the same time in such a way that only these two, three, four or more actuators are opened at the same time while all other ejectors are either fully open or fully closed. This solution allows for a faster increase in total mass flow by displacing the common actuator while still keeping a proportional control of the mass flow through the whole ejector arrangement.
It is preferred if the common actuator comprises a pilot valve wherein the pilot flow is controlled by an electric valve. This solution is preferable if the pressure differences in the ejector arrangement are large and it may thus be difficult to control a non-piloted valve. The electric valve may be a magnetic valve or a stepper motor valve.
In a preferred embodiment the common actuator comprises an actuating element with a plurality of orifices, each of which accommodates a valve element. The valve elements may in this case only move along the common axis inside the respective orifice. The orifices may have the shape of channels along the common axis inside the actuating element. The orifices may have a first end with a cross section that is smaller than the largest parallel cross section of the corresponding valve element. In this case the valve element may thus only fully enter or exit the orifice at the second end of the orifice. Preferably, the second end of the orifice may be closed, e.g. by a plug, after the valve element has been inserted. This allows for a simple assembly with the valve elements arranged in the actuating element.
It is preferred if the valve elements comprise a section with a larger cross section and a section with a smaller cross section, wherein at least two valve elements comprise sections with a smaller cross section that have a different length along a common axis. In this case the relative length of the sections of different cross section may be different for each valve element to adjust when the common actuator starts to displace the individual valve element while being displaced along the common axis. The sections may have the shape of two cylinders of different diameter, that are connected at an end face of the cylinders. The valve elements may comprise an annular shoulder that may engage a stop of the common actuator for each valve element. The length of orifices in which the valve elements may be received is preferably the same for all valve elements in this embodiment.
In a further preferred embodiment the housing comprises a circumferential wall, wherein the outlets are arranged radially outside the circumferential wall and the suction inlets are arranged radially inside the circumferential wall. This solution allows for a compact construction of the ejector arrangement, for example when the common housing comprises a cylindrical body. In the latter case the circumferential wall may also have a substantially cylindrical shape.
In another preferred embodiment each ejector is sealed to an end face of the housing. This way one may ensure that in a region encircled by the combination of the ejectors the suction flow has a flow path to all suction inlets of the injectors. On the other hand one may also ensure that in a region radially outside of the combined ejectors the fluid flow from the individual outlets of the ejectors may be guided, for example into a common outlet chamber.
Preferably a common outlet line connected to all ejector outlets is arranged in the housing. This common outlet line may for example be connected to an outlet chamber connected to all outlets of the individual ejectors.
Preferably all outlets are connected to an outlet chamber in the housing. This outlet chamber may, for example, be arranged radially outside a circumferential wall in the housing.
In a further preferred embodiment, a common motive line connected to all motive inlets is arranged in the housing.
A preferred embodiment of the invention will now be described in more detail with reference to the drawings, wherein:
Referring to
A motive line 10 provides high pressure motive fluid to all motive inlets 4, 5. All ejectors 2, 3 are arranged in a common housing 11. The housing 11 comprises a cylindrical body 12. The cylindrical body 12 is substantially rotationally symmetric around a common axis 13.
The motive fluid enters through the motive line 10 into a motive chamber 14 neighboring all motive inlets 4, 5.
All outlets 8, 9 of the ejectors 2, 3 lead the fluid into an outlet chamber 15. The outlet chamber is arranged radially outside a circumferential wall 16 in the housing 11. The outlet chamber 15 is connected to an outlet line 17.
All ejectors 2, 3 are arranged in parallel to the common axis 13. Both the motive line 10 and the outlet line 17 enter the housing 11 perpendicular to the common axis 13. A suction line 18 enters the common housing 11 parallel to the common axis 13. The suction line 18 is connected to an end face 19 of the housing 11.
All ejectors 2, 3 are sealed to the end face 19 of the housing 11. Radially inside the circumferential wall 16 a suction chamber 20 is arranged connected to the suction line 18 and all suction inlets 6, 7. At the suction inlets 6, 7 non-return valves 21, 22 are arranged, in this case ball-valves.
The ejector arrangement 1 further comprises one valve element 23, 24 for each ejector 2, 3. When an ejector 2, 3 is inactive the respective valve element 23, 24 closes the respective motive inlet 4, 5 such that no motive fluid coming from the motive line 10 can enter the ejector 2, 3.
The valve elements 23, 24 are arranged in a common actuator 25. The common actuator 25 comprises an actuating element 26 as well as a valve member 27. The common actuator 25 in this case comprises a pilot valve, wherein the pilot flow is controlled by a magnetic valve. The solenoid of the magnetic valve is not shown in the figures for simplicity.
The pilot valve here comprises a pilot chamber 28 as well as a pilot hole 29. The pilot hole 29 may be opened or closed by actuating the valve member 27. A tip 30 of the valve member 27 engages the pilot hole 29 and closes the pilot chamber 28 from a fluid connection to the suction line 18 when the common actuator is not activated.
Referring to
In
As can be seen in
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The difference in the opening behavior between the individual ejectors 41, 44 in this embodiment is reached by having orifices 49, 50 with a different length for each ejector 41, 42. At the same time the stop 51 of the ejector 41 engages the shoulder 52 of the valve element 43 earlier than the stop 53 engages the shoulder 54 of the valve element 44 when the common actuator 55 is moved towards an opening direction, i.e. in this case upwards. The advantage of the second embodiment compared to the first embodiment is that the assembly of the ejector arrangement is simplified, because all valve elements 43, 44 are the same and thus there is no risk of a wrong assembly by inserting a valve element into a wrong orifice. The common actuator 55 in the second embodiment thus comprises an asymmetric actuating element 56 with orifices 49, 50 having a different length for each orifice 49, 50. According to the first embodiment in
While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15173582.6 | Jun 2015 | EP | regional |
This application is a National Stage application of International Patent Application No. PCT/EP2016/061739, filed on May 25, 2016, which claims priority to European Patent Application No. 15173582.6, filed on Jun. 24, 2015, each of which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/061739 | 5/25/2016 | WO | 00 |
