EP1991818A1

EP1991818A1 - Expansion valve for an air conditioner

Info

Publication number: EP1991818A1
Application number: EP07702921A
Authority: EP
Inventors: Axel MÜLLER; Rene Schulz
Original assignee: Thomas Magnete GmbH
Current assignee: Thomas Magnete GmbH
Priority date: 2006-02-02
Filing date: 2007-01-20
Publication date: 2008-11-19
Also published as: DE102006004781B4; DE102006004781A1; WO2007087992A1

Abstract

The invention relates to an expansion valve for coolant of an air conditioner circuit for mobile applications such as a motor vehicle. Said expansion valve comprises at least one coolant inlet and outlet (2), functional valve mechanisms for actuating and controlling the same, and a pressure-proof envelope (8, 11) which surrounds the valve (1). The invention is characterized in that the expansion valve (1) comprises a valve block (11) in which the coolant inlet and outlet (3), all functional valve mechanisms, and the envelope (8, 11) form an integral part while also comprising an emergency discharge device (12) by means of which the coolant is discharged from the air-conditioning circuit in case of an emergency.

Description

Expansion valve for air conditioning

The invention relates to expansion valve for refrigerant of an air conditioning circuit for mobile applications such as a motor vehicle according to the preamble of claim 1. In a typical air conditioning circuit with the refrigerant R 744 for mobile applications such as in a car, a refrigerant based on CO ₂ with the Designation R 744 from the low-pressure area to the high-pressure area of more than 100 bar and then flows through an external heat exchanger in the transcritical state, in which incoming air ensures cooling of the refrigerant. Before entering an expansion element, an internal heat exchanger further cools the fluid. The expansion element consists of a thermostable expansion valve in which the reduction of the fluid pressure takes place by the throttling process. In a subsequent evaporator, the refrigerant absorbs heat from the air flowing into the interior of the vehicle.

R 744, operated in the supercritical range, has a pressure range three times higher than the conventional refrigerant R 134a, which due to its high global warming potential is to be substituted by R 744, since the latter is neutral in terms of the damage to the ozone layer.

The high pressure level at R 744 requires a correspondingly pressure-resistant design of all its components for the expansion valve in order to avoid external leakages of the refrigerant and the resulting pressure drop. For this purpose, in other applications than R 744 usually seals made of elastomeric material in the form of O-rings used. However, the use of plastics and elastomers is problematic for components in contact with R 744 because of their solution properties for R 744 they tend to fail by explosive decompensation. Expansion valves can be carried out in cartridge design. Such a cartridge valve is sealed via separate sealing elements in a separate block. As another embodiment, valves are known which are screwed with a sealing adhesive into a separate valve block containing the corresponding ports. The seal in the block interior between high and low pressure side takes over a special sealing element.

In mobile applications, such as in a motor vehicle, additional passive safety measures must be provided for the refrigerant CO _{2 to} prevent uncontrolled escape of the refrigerant. An uncontrolled release of the refrigerant R 744 in high concentrations in the passenger compartment, for example, lead to damage or health effects of inmates. DE 103 05 947 A1 shows a generic expansion valve for a refrigerant for regulating the high pressure of an air conditioner. The valve is designed as a cartridge valve and works as a slide valve, in which internal leakage can not be completely avoided. The valve body has a pressure-tight enclosure, but inlet and outlet of the valve must be sealed against each other in the additionally required valve block. In order to be able to reduce external leakage relative to the external environment, these can hardly be completely avoided with the solution proposed in DE 103 05 947 A1, further sealing devices are essential. A safety function for a drain of the refrigerant in the event of an accidental crash is not provided.

DE 102 19 667 A1 shows a further expansion valve for the refrigerant R 744, in which the valve parts are integrated in a valve sleeve called as a screw sleeve. The screw sleeve is Surrounded by a valve block in which channels are arranged for the inflow and outflow. The screw sleeve creates additional leaks to be sealed. Even with this arrangement, no safety function is provided for the drainage of the refrigerant in the event of an accidental crash.

DE 196 46 849 C1 shows an arranged outside the passenger compartment emergency lowering device for an air conditioner of a motor vehicle in a crash-related accident. The device is designed in the form of a nozzle which, in the event of a crash, generates an opening of the refrigerant circuit to the outlet of the refrigerant. It is also proposed that the air conditioning system each have a separate drain valve on the individual modules, which can be activated via safety-related sensors.

Another emergency lowering device shows DE 102 41 367 A, which uses a pyrotechnic actuator to trigger the refrigerant flow.

It is the object of the invention to provide a cost-effective, compact expansion valve in pressure-resistant design with extremely low leakage with an additional safety device. The object is achieved in combination with the preamble by the characterizing features of claim 1.

In air conditioning systems for mobile applications, the avoidance of external leakage is a significant qualitative differentiator. For this purpose, the number of points to be sealed is kept as low as possible. This is particularly important in applications for the refrigerant R 744, since in addition to the known elastomeric seals only very expensive alternatives (metallic seals, etc.) come into consideration. It is therefore proposed to address the difficulties involved in the use of plastics and elastomers for the refrigerant R 744. To bypass beating parts, in the solution according to the invention not only to reduce the number of points to be sealed by functional integration, but generally to bring about a complete seal both internally and externally. In this sense, the valve block itself assumes the function of a sealing element to be provided according to the prior art between the high and a low pressure side of the expansion valve. The screwing of the valve with a time-consuming bonding, which also makes high demands on the cleanliness of the thread, completely eliminated.

External leakage is reliably avoided, as sealing elements are superfluous - except for the unavoidable pipe line connections for the refrigerant. The space in which the refrigerant is located, by the cohesive connection of pole tube and block gas-tight to the outside. In addition to cost savings, the design of the valve as a block valve with a smaller number of components offers a market advantage due to a possible integration of additional functions.

The valve according to the invention is designed as a block valve, whereby a separate valve block can be omitted to achieve compact overall dimensions. The direct integration of valve components into the valve block reduces the number of components without sacrificing overall functionality.

In the valve block, a device for discharging the refrigerant is installed in addition to increasing the passive safety. Through a targeted opening of the valve block itself, the refrigerant can escape from the air conditioning circuit. Additional special safety devices such as drain valves or the like on components are no longer required. By providing the necessary safety functionality for the circuit directly through the expansion valve is taken over, account for further components for the air conditioning cycle. Prior to the release of the emergency lowering device, the pressure-tight space in which the refrigerant circulates under high pressure is separated from the exterior of the air conditioning system. This is also ensured for refrigerants which have a high permeation tendency. The proposed emergency lowering device is a safety device and therefore triggers quickly.

The additional safety device in the form of the emergency lowering device comes without additional connection points. Additional sealing measures are not required.

Advantageously, the emergency lowering device is arranged outside the passenger compartment of the vehicle, so that the refrigerant is discharged outside this cell in an emergency, as mentioned, in particular the refrigerant R 744 in high concentrations could affect the health and safety of passengers in the passenger compartment.

In a further advantageous embodiment of the invention, the Notablasvorrichtung is triggered by an accident-related event. For this purpose, the device has a release pin which, in the event of activation, can be combined by an actuator which can be actuated electromagnetically, pyrotechnically, mechanically and / or manually and which can be combined, for example, with the deployment mechanism of the airbag, the safety belts, an active headrest or other safety devices and their trigger signal can use. The actuator is preferred, but not necessarily outside the pressure chamber in which the refrigerant is located. The defined opening of the system takes place in the event of damage by the actuator, for example, by an electrical signal, a trigger pin moves. The trip signal may also be from a sensor inside the vehicle. Gastraumes are generated, provided that a critical concentration of the refrigerant is detected.

The emergency lowering device can be reversible or irreversible, wherein preferably the above-mentioned additional electromagnetic actuator for the reversible solution comes into question, while the irreversible discharge device would preferably be operated using the pyrotechnic actuator or also an electromagnetically actuated actuator.

Because the refrigerant can not only be drained off via the reversible device, but also in the refrigeration cycle by an additional (re) filling device or refilled. A targeted opening of the outer wall, through which the pressurized refrigerant can escape, takes place by displacing a sealing or seat body, preferably a ball, which is in the untripped state in the sealing position. It is in it - preferably by self-retention, d. H. by friction or alternatively by spring force - held. When triggered, the seat body is moved by means of a plunger, which is actuated by the actuator, out of its seat and thus releases the path of the refrigerant out of the air conditioning circuit to the outside. The seat is designed in such a way that the ball is pressed into the seat when the inside of the circuit is over-pressurized, thus meeting the pressure requirements. The ball seat must be secured against possible negative pressure in the interior of the circle, preferably by self-locking the ball in a conical seat with a smaller cone angle.

By destroying preferably a part of the outer wall, an opening for discharging the refrigerant is generated, this is irreversible. In this case, the draining off of the refrigerant can be realized by a targeted opening at a predetermined breaking point provided for this purpose. Siert, preferably a bursting disc or a prepared for the same purpose position of the outer wall.

Alternatively, the opening can be made by piercing the outer wall with a mandrel or a hollow body, preferably a hollow needle, so that the refrigerant escapes indirectly through the interior of the hollow body. The hollow body opens a locally prepared point in the outer wall. This may be a discontinuous wall thickness distribution, a special use in the outer wall, which itself seals the pressure chamber in the untriggered state, or with the aid of a membrane or a combination of both solutions. As examples of such inserts are metal foams preferably having a pore-free surface of the same material or also a membrane which seals the pressure chamber and by a special component of foam (metal, plastic, etc.), ceramic or plastic is supported.

As an alternative to puncturing the membrane with a hollow body, the membrane can also cause an opening of the outer wall by causing it itself to break or rupture, thus allowing the refrigerant to flow out. The valve according to the invention is preferably actuated electromagnetically. The valve function has for this purpose a control or valve spool, which is actuated by the armature of an electromagnet and which is moved directly in the block, which also includes all external connections for the inflow and outflow of the refrigerant. The pole core and the cone of the electromagnet are incorporated in the design directly into the valve block.

In order to ensure that no external leakage occurs in the area of the electromagnet or other actuator for the valve, the pressure-resistant enclosure of the magnet, referred to as a sleeve, is connected directly to the control capacitor of the actuator. kergegenstückes of the magnet joined. This is preferably done cohesively, such as by welding. This completes this part of the valve pressure-resistant and leak-free. Furthermore, in this way can be dispensed with the elastomeric sealing of the armature space by means of O-rings, so that the assembly can be simplified. The valve block facing away from the end of this sleeve is preferably designed hemispherical to meet the pressure requirements.

The valve block is fixed and leak-free connected to the envelope of the valve. To avoid a further interface between the casing and the valve block, both parts may alternatively consist of a single block. If the valve stem is made of non-magnetic material, the control cone for the magnetic flux guide must be made of magnetizable material as a separate part. In this case, it is preferably joined in a metallic sealing manner with the valve block.

Further advantageous embodiments of the invention will become apparent from the dependent claims and the embodiments illustrated in the drawings. Fig. 1 shows a longitudinal cross section through the expansion valve according to the invention with emergency lowering device.

Fig. 2 to 6 show different variants of the emergency lowering device.

1 shows a schematic diagram in the form of a longitudinal cross-section through an expansion valve 1 according to the invention, which is used as an expansion element in an air conditioning system. It serves to regulate the high pressure in a transcritical CO ₂ climate cycle in mobile applications. This happens because the refrigerant in the expansion valve targeted to a lower pressure is throttled (expansion organ). The internal pressure of the refrigerant is thereby reduced in an isenthalpic expansion.

The valve 1 according to the invention has an inlet and a drain 2 in the form of channels, the connection of which can be opened or closed in the desired manner via a valve slide 3. Also intermediate positions can be regulated analogously. The inlet and outlet 2 respectively forms the high or low pressure side of the valve 1, depending on the direction of the refrigerant. Since the valve can be flowed through bidirectionally, the inlet and the outlet 2 each have the same reference numerals. The throttling of the refrigerant takes place inside the valve.

The valve functions are actuated electromagnetically by a cup-shaped electromagnet 4 shown in the upper area of FIG. 1 by means of magnet armature 5, which is driven by an externally arranged magnet coil 6 with yoke 24, which is acted upon by a plug element 7 with a corresponding drive signal. The electromagnet 4 is surrounded by a housing 8, in which the magnetic coil 6 and the plug element 7 are integrated. The housing 8 thus forms a space which is closed inwardly by a coaxial with the axis of the armature 5 cup-shaped sleeve 9, which serves as a guide for the lifting movement of the armature 5, wherein the open end of the sleeve 9 in the direction of the lifting movement of the armature 5 is arranged and the sleeve bottom forms the rear Hubbegrenzung and is executed like a ball. The open end of the sleeve 9 is mounted directly on the outer wall of the control cone 10 of the electromagnet 4, the control cone 10 and the associated pole 13 in turn being part of a valve block 11, which is shown in the lower part of FIG. In the valve block 11, all valve functional devices of the valve part of the expansion valve 1, such as the slide 3, the inlet or drain 2 and additionally an emergency drain device 12 integrated, which will be described in more detail below. Control cone 12 and pole 13 thus form an adapter for the valve block 11. When the valve block 11 is made of a non-magnetic material, the cone 12 must be made of magnetizable material and, unlike in Fig. 1, as a separate part. It is then joined to the valve block 11 and sealed separately.

In the illustration of Fig. 1, the sleeve 9 of the electromagnet 4 and the valve block 11 are designed as separate components, which are joined via a junction pressure and free of leakage. Alternatively, both components can also be designed as a compact unitary component that does not require a joint.

The connection between sleeve 9 and control cone 10 is preferably cohesively. This not only creates a pressure-resistant anchor interior, but also a safe external leakage-free valve interior. In this way, it is possible to dispense with an additional, for example elastomeric, sealing of the armature space by means of O-rings, so that the assembly can be simplified and carried out in a process-proof manner.

The valve spool 3 is arranged in an axial vertical bore 16 shown in Fig. 1. By the vertical lifting movement of the armature 5 upwards, the valve slide 3 is moved from the dargstellten closed position for the inlet and outlet 2 arranged perpendicular thereto in an open position. By the voltage applied to the plug element 7 control signal, the valve spool movement and thus the passage rate for the refrigerant can be controlled. A spring 15 acts as a counterforce against the valve slide moved by magnetic force, which acts with its upper end against the valve slide 3 and acts on its opposite end. set end is supported at the bottom of the bore 16. Thus, a balance of power between the substantially acting magnetic force and the spring force is generated.

To reduce the pressure forces on the valve spool 3, channels, openings or holes can be arranged on or in the slider 3.

The emergency lowering device 12 according to the invention is integrated in the representation of FIG. 1 in the valve block 11. The device 12 comprises an additional actuator 19 which is activated, for example, by a signal which is generated by sensors in the vehicle in the event of a crash or accident. The valve block has for this purpose an outwardly sealed channel 17, which runs parallel to the inlet or outlet opening channel 2 in Fig. 1, and opens into the valve interior, in which the refrigerant is located. In the illustration of Fig. 1, the channel 17 opens in the valve spool bore 16. The discharge point is closed by a closure 18 during normal operation of the valve 1. In an emergency, the closure 18 is pushed by a ram 14 attached to the actuator 19 from its closed position to an open position. The refrigerant can thus flow through the channel 17 from the valve interior into a tank arranged outside the passenger compartment or into the open air.

The closure 18 of the emergency lowering device 12 can be made reversible and non-reversible, wherein FIG. 2 shows an embodiment for the reversible embodiment. The closure 18 of FIG. 1 is designed in the representation of FIG. 2 as a seat or sealing body in the form of a ball 20, which is brought by the plunger movement of the actuator 19 from its sitting or closed position into the open position. For better centering of the ball 20 whose bearing point in the valve block 11 is conically shaped, the Contour towards the valve interior opens, so that due to the pressure difference between the valve interior and the outside of the ball 20 is centered by itself in their seat.

In the irreversible embodiment of the Notabassvorrichtung 12 of FIGS. 3 to 6 of the plunger 14 of the actuator 19 is designed as a hollow needle 21, the top of the outer wall pierces the valve block 11 to the valve interior by the actuation of the actuator 19. The refrigerant can thus flow through the interior of the hollow needle 21. Due to the design as a hollow needle 21, the channel 17 can be sealed leakage-free with the plunger 14. The puncture point of the hollow needle 21, as shown in the embodiment in Fig. 4, are performed by a discontinuous wall thickness distribution of the valve block 11 at the site. For a predetermined breaking point for the flow of the refrigerant is realized. Fig. 5 shows the SoII- fracture parts as a foam insert 22 in the outer wall of the valve block 11. To avoid leakage or pressure losses from the valve interior, the predetermined breaking point in the sealed state, as shown in Fig. 6, additionally supported by a membrane 23 become.

Claims

claims

1) Expansion valve for refrigerant of an air conditioning circuit of an air conditioning system for mobile applications such as a motor vehicle, comprising at least one inflow and outflow (2) of the refrigerant and valve function means for its actuation and control and a pressure-resistant enclosure surrounding the valve (1) (8, 11), characterized in that the expansion valve (1) has a valve block (11) in which the inflow and outflow (2) of the refrigerant, all valve functional means and the envelope (8, 11) are an integral part and an emergency lowering device (12 ), with which the refrigerant is discharged from the air conditioning circuit in an emergency.

2) Expansion valve according to claim 1, characterized in that the emergency lowering device (12) is arranged outside the passenger compartment of the vehicle.

3) Expansion valve according to claim 1 or 2, characterized in that the Notablasvorrichtung (12) is triggered by an accident-related event.

4) Expansion valve according to one or more of claims 1 to 3, characterized in that the emergency lowering device (12) comprises an actuator (19) acting on a triggering device.

5) Expansion valve according to claim 4, characterized in that the actuator (19) electromagnetically, pyrotechnically, mechanically and / or manually operable and can be combined with safety devices of the vehicle.

6) Expansion valve according to claim 4 and 5, characterized in that the actuator (19) outside the valve block (11) is arranged.

7) Expansion valve according to claim 4 and 5, characterized in that the actuator (19) within the valve block (11) is arranged.

8) Expansion valve according to one or more of claims 1 to 7, characterized in that the emergency lowering device (12) operates irreversibly.

9) Expansion valve according to claim 8, characterized in that the irreversible embodiment comprises a supported membrane (23), a porous insert (22) or a predetermined breaking point on the sheath (8, 11).

10) Expansion valve according to one or more of claims 1 to 7, characterized in that the emergency lowering device (12) operates reversibly.

11) Expansion valve according to claim 10, characterized in that the reversible design comprises an additional body in the sealing seat (20).

12) Expansion valve according to claim 10 or 11, characterized in that the reversible embodiment comprises a refilling device for the refrigerant. 13) Expansion valve according to one or more of claims 1 to 12, characterized in that the valve function comprises an actuated by an armature of an electromagnet valve slide (3).

14) Expansion valve according to claim 13, characterized in that the valve block (11) comprises the pole core (13) and the control cone (10) of the electromagnet.

15) Expansion valve according to one or more of claims 1 to 14, characterized in that the valve block (11) fixed and leak-free with the sheath (8, 11) of the valve (1) is connected.

16) Expansion valve according to one or more of claims 1 to 15, characterized in that the valve block (11) and the sheath (8) form a material unit.

17) Expansion valve according to one or more of claims 1 to 16, characterized in that the refrigerant comprises CÜ ₂ (R 744) in transcritical application.