Field of the Invention

The present invention relates to a thermostatic mixing valve comprising a valve housing with a hot fluid inlet, a cold fluid inlet, a fluid mixing chamber for receiving fluid from the hot and the cold fluid inlet, and a fluid outlet in fluid communication with the fluid mixing chamber, a spring-biased flow control assembly for controlling flow of fluid to the fluid mixing chamber, a spring, and a thermostat device for operating the flow control assembly, the flow control assembly being arranged to be biased by the spring, wherein the flow control assembly is adapted to be moved by the thermostat device in response to a temperature of the fluid in the mixing chamber such as to close and open a respective fluid communication of the cold fluid inlet and hot fluid inlet with the fluid mixing chamber such as to maintain said temperature at, or at least close to, a preset temperature.

Background of the Invention

Thermostatic mixing valves may be used to regulate the fluid temperature in emergency showers or eyewashers.

Such thermostatic mixing valves may be provided with a cold fluid bypass arrangement in order to secure a flow of fluid in the event of hot fluid supply failure.

US 8,500,035 discloses a thermostatic mixing valve including a cold water bypass passageway that opens upon a failure of a hot water supply.

A drawback of this thermostatic mixing valve is that it may be considered to be complex.

Summary of the Invention

It is an object of the present invention to overcome the above described drawback, and to provide an improved thermostatic mixing valve.

This and other objects that will be apparent from the following summary and description are achieved by a thermostatic mixing valve according to the appended claims. According to one aspect of the present disclosure there is provided a thermostatic mixing valve comprising a valve housing with a hot fluid inlet, a cold fluid inlet, a fluid mixing chamber for receiving fluid from the hot and the cold fluid inlet, and a fluid outlet in fluid communication with the fluid mixing chamber, a spring-biased flow control assembly for controlling flow of fluid to the fluid mixing chamber, a spring, and a thermostat device for operating the flow control assembly the flow control assembly being arranged to be biased by the spring, wherein the flow control assembly is adapted to be moved by the thermostat device in response to a temperature of the fluid in the mixing chamber, wherein the spring is arranged between the flow control assembly and a cup-shaped portion of said valve housing, said fluid communication of the cold fluid inlet with the fluid mixing chamber occurring around said cup- shaped portion, and the thermostatic mixing valve comprises a cold fluid bypass opening being an opening in said cup-shaped portion, a bypass closure member movable between a closed position in which said cold fluid bypass opening is closed by the bypass closure member and an open position in which the cold fluid bypass opening is open and allows a bypass flow of cold fluid to the mixing chamber through said cold fluid bypass opening, and a holding device arranged to apply a holding force to the bypass closure member to hold the bypass closure member in the closed position, and wherein the bypass closure member is arranged to be moved from the closed position to the open position when a pressure force exerted to a pressure surface of the bypass closure member by cold fluid in the cold fluid inlet exceeds said holding force.

A thermostatic mixing valve according to the present disclosure allows a compact and simple valve design. Furthermore, it provides for easy and quick installation of the valve in a system.

During normal operation of the thermostatic mixing valve the bypass closure member is held in the closed position by the holding device. In case of a hot fluid supply failure, such as a hot water supply failure, the thermostat device moves the flow control member toward a position in which the ordinary cold fluid passageway through the valve is closed. Since the ordinary cold fluid opening is blocked the pressure force acting on the pressure surface of the closure member is then increasing and when the pressure force exerted to the pressure surface exceeds the holding force the bypass closure member is urged away from the closed position, thereby allowing flow of cold fluid from the cold fluid inlet to the mixing chamber. Hence, cold fluid is allowed to enter the mixing chamber although the thermostat device holds the fluid control member in a position in which it blocks the normal cold fluid path through the valve. This has the advantage that a sufficient flow of fluid may be delivered even upon a hot fluid failure.

Hence, this thermostatic mixing valve includes a cold fluid bypass passageway controlled by a pressure-operated closure member that opens upon a failure of a hot fluid supply to the valve. The thermostatic mixing valve may be used with safety devices, such as eyewash and drench shower stations, and allows the continued delivery of cold fluid upon hot fluid supply failure. The thermostatic mixing valve may thus allow continued delivery of cold water upon hot water supply failure.

Hence, in a normal operating mode the closure member is held in the closed position by the holding device and in a bypass operating mode the bypass closure member is held in the open position by a pressure force exerted thereon by cold fluid in the cold fluid inlet.

According to one embodiment said bypass opening is formed in a bottom wall of said cup-shaped portion.

According to one embodiment bypass opening is situated centrally in said bottom wall.

According to one embodiment said bypass opening is a central opening in a base surface of the cup-shaped portion, such as a bottom cup, of said valve housing. The bypass opening may thus be arranged in a base surface of a bottom cup of the valve housing.

According to one embodiment the central opening is circular or elliptical.

According to one embodiment the central opening is circular with a diameter of 6-20 mm, more preferably 8-18 mm and most preferably 1 1 -15 mm.

According to one embodiment the area of the central opening is 30-314 mm ² , more preferably 50-250 mm ² and most preferably 95-180 mm ² .

According to one embodiment the central opening is surrounded by a seat against which the bypass closure member is biased by the holding device. According to one embodiment the holding device comprises a spring and preferably a conical spring.

According to one embodiment the spring is a coil spring.

The bypass closure member may thus be spring-biased, which provides for a robust and reliable bypass arrangement.

According to one embodiment said bypass closure member is discshaped.

According to one embodiment the hot fluid inlet and the cold fluid inlet are disposed perpendicular to each other in order to provide a certain flow pattern. Then, the valve employs an L-shaped flow pattern, which enables the valve to be installed in a system in a very easy and quick manner.

Furthermore, it may facilitate service and maintenance of the valve and/or the system in which the valve is installed. The valve may thus be an L-pattern thermostatic mixing valve.

According to one embodiment the hot fluid inlet and the cold fluid outlet are disposed opposite to each other in order to provide a certain flow pattern.

According to one embodiment the hot fluid inlet and the fluid outlet are disposed opposite to each other and the cold fluid inlet is disposed

perpendicular to each of the hot fluid inlet and the fluid outlet. Hence, in this embodiment the valve ports of the thermostatic mixing valve are arranged in a T-configu ration.

According to one embodiment the spring being arranged to bias the flow control assembly is a compression spring.

According to another aspect of the present disclosure there is provided a safety shower system, such as an eyewash or emergency shower system, which safety shower system comprises a thermostatic mixing valve according to the present disclosure.

These and other aspects of the invention will be apparent from and elucidated with reference to the claims and the embodiments described hereinafter. Brief description of the drawings

The invention will now be described in more detail with reference to the appended schematic drawings in which:

Fig. 1 is a cross section showing a thermostatic mixing valve according to an embodiment of the present disclosure in a normal operating mode.

Fig. 2 is a cross section showing the thermostatic mixing valve shown in Fig. 1 upon a hot water supply failure.

Description of preferred embodiments

Fig. 1 illustrates a thermostatic mixing valve 1 , in the form of an L- pattern thermostatic mixing valve, according to an embodiment of the present disclosure. The thermostatic mixing valve 1 comprises a housing 3 with a hot water inlet 5, a cold water inlet 7, a mixing chamber 9 for receiving water from the hot and the cold water inlet, as illustrated by the arrows A and B, respectively, in Fig. 1 . The hot fluid inlet 5 and the cold fluid inlet 7 are disposed perpendicular to each other. In this embodiment, the thermostatic mixing valve thus employs an L-shaped flow pattern, although other flow patterns, such as a T-shaped flow pattern, are possible. The mixed water exits the mixing chamber 9 through a fluid outlet 1 1 .

The desired fluid temperature is preset by means of a schematically shown actuator 13. The actuator 13 presets the temperature in a known manner by screwing in or out an adjustment screw 13a inserted in the upper part of the valve housing 3.

The thermostatic mixing valve 1 further comprises a flow control assembly 15, a spring, in the form of a compression spring 17, and a thermostat device 19. The compression spring 17 is arranged to bias the flow control assembly 15. The flow control assembly 15 is thus spring-biased by the compression spring 17. The compression spring 17 is arranged between the flow control assembly 15 and a cup-shaped portion, in the form of a bottom cup 4, of the valve housing 3. The cup-shaped portion 4, which is a stationary part of the valve 1 , comprises a bottom wall 41 and a side wall extending upwardly from the bottom wall 41 . Fluid communication of the cold fluid inlet 7 with the fluid mixing chamber 9 may occur around said cup- shaped portion 4. The flow control assembly 15 comprises a valve piston 21 which is continuously movable between a first seat 23 with closed hot water inlet 5 and opened cold water inlet 7 and a second seat 25 with closed cold water inlet 7 and opened hot water inlet 5. Hence, when the valve piston 21 is seated against the first seat 23 fluid communication between the hot water inlet 5 and the mixing chamber 9 is blocked by the valve piston 21 and when the valve piston 21 is seated against the second seat 25 fluid communication between the cold water inlet 7 and the mixing chamber 9 is blocked by the valve piston 21 . When the cold fluid inlet 7 is open the fluid communication of the cold fluid inlet 7 with the fluid mixing chamber 9 occurs around the cup-shaped portion 4 of the housing 3.

The thermostat device 19 comprises a temperature responsive control member 27 which is arranged in the mixing chamber 9 for affecting the valve piston 21 according to the preset temperature. The temperature responsive control member 27 and the valve piston 21 are movable together in the mixing chamber 9, immobilized in relation to each other.

The temperature responsive control member 27 is arranged to respond to the temperature in the mixing chamber 9 by means of a thermostat piston 31 slidable in a sleeve 33 formed integrally with the temperature responsive control member 27. The position of the adjustment screw 13a of the actuator 13 defines an end position for the thermostat piston 31 and corresponds to the desired fluid temperature in the mixing chamber 9.

The temperature responsive control member 27 comprises a wax element enclosed in a casing 29 and responding to the temperature of the fluid in the mixing chamber 9 by expanding with rising temperature or contracting with falling temperature. When expanding, the thermostat piston 31 , is pushed upwards in a sleeve 33, moving the valve piston 21 downwards against the action of the spring 17. This closes the hot water inlet 5 and opens the cold water inlet 7. When contracting, the valve piston 21 is pushed upwards by the action of the spring 17, pressing the thermostat piston 31 into the sleeve 33.

The flow control assembly 15 is thus adapted to be moved by the thermostat device 19 in response to a preset temperature. The thermostat device 19 senses the temperature of fluid in the mixing chamber 9 and regulates the flow of hot fluid as needed, to maintain the temperature at, or at least close to, the preset temperature.

The mixing valve 1 further comprises a cold water bypass opening, in the form of a central opening 35 in the bottom cup 4 of the valve housing 3, a bypass closure member 37 and a holding device in the form of a conical coil spring 39. The central opening 35 is disposed in a base surface of a bottom wall 41 of the bottom cup 4 of the valve housing 3.

The bypass closure member 37 is movable between a closed position in which the cold water bypass opening 35 is closed by the bypass closure member 37 and an open position in which the cold water bypass opening 35 is open and allows flow from the cold water inlet 7 to the mixing chamber 9.

The bypass closure member 37 comprises a disc-shaped closure portion 43, which is spring-biased by the conical spring 39 against a seat 45 surrounding the bypass opening 35, and a stem 47 which is fixed to the discshaped closure portion 43.

The holding device 39 is thus arranged for applying a holding force to the valve closure member 37, which holding force holds the bypass closure member 37 in the closed position.

During normal operation of the thermostatic mixing valve 1 , i.e. when hot and cold water supply is present, the bypass closure member 37 is held in the closed position by the holding device 39.

The thermostatic mixing 1 valve may be used to regulate the fluid temperature in emergency shower or eyewash systems. In such systems it is desired to continue deliver a predetermined flow even in the event of hot water supply failure.

Now referring to Fig. 2 the function of the thermostatic mixing valve 1 will be further described.

Upon hot water supply failure in a safety system, such as an eyewash shower system or a drench shower system, fitted with the thermostatic valve 1 the thermostatic device 19 acts to move the valve piston 21 toward the seat 25, thereby blocking cold water supply through the ordinary path through the thermostatic mixing valve 1 . Then, the pressure force PF exerted to the pressure surface 49 of the disc-shaped closure portion 43 by cold water in the cold water inlet 7 increases. When this pressure force exceeds the predeternnined holding force the disc-shaped closure portion 43 will be urged away from the valve seat 45, i.e. moved to an open position. In the open position, illustrated in Fig. 2, the closure member 37 allows cold water to pass through the bypass opening 35 as illustrated by the arrow D in Fig. 2.

Hence, upon a pressure force PF, exerted to the pressure surface 49 of the bypass closure member 37 by fluid in the cold water inlet 7, that exceeds the holding force exerted by the holding device 39 a bypass path through the flow control assembly 15 is opened, causing cold water to enter the mixing chamber 9, as illustrated by arrows D in Fig. 2, and exit the same via the fluid outlet 1 1 .

Hence, upon a hot water supply failure the lack of hot water causes an ordinary cold water opening to be closed by the thermostatic device, the wax element of which retracts upon the lack of hot water.

The bypass passageway, illustrated by arrows D in Fig. 2, formed by the bypass opening 35 is adapted to allow sufficient flow of cold water to bypass the ordinary opening and be directed to the mixing chamber 9.

Upon hot water supply failure, the ordinary cold water passageway, which is formed around the cup-shaped portion 4 of the housing 3, is thus bypassed whereby a cold water bypass flow occurs through the cold fluid bypass opening 35.

A sufficient cold water flow may thus be delivered in the emergency system comprising the thermostatic mixing valve 1 upon a hot water supply failure.

It will be appreciated that numerous variants of the embodiments described above are possible within the scope of the appended claims.

For example, various types of adjustment means, temperature responsive control members and actuators could be used.