Patent Publication Number: US-2007119989-A1

Title: Flow channel switching valve and shower system

Description:
TECHNICAL FIELD  
      The present invention relates to a channel switching valve and a shower system.  
     BACKGROUND ART  
      Conventionally, as a channel switching valve, an arrangement disclosed in Patent Document 1 is known, for example. The channel switching valve comprises a temperature sensitive spring which reversibly changes its shape depending on the temperature of fluid flowing into the inside of the channel switching valve and a valve body which is biased by the temperature sensitive spring. When load is applied to the valve body with change in shape of the temperature sensitive spring, the valve body moves to switch between a state in which a drain port for fluid having a proper temperature, which is fluid having a temperature in a predetermined temperature range, is linked to the channel and a state in which a drain port for fluid having an improper temperature, which is fluid having a temperature out of a predetermined temperature range, is linked to the channel.  
      If this kind of channel switching valve is applied to a shower system which is used in a bath, for example, it is possible to have an arrangement in which hot water, which is water having a proper temperature, is drained from a shower head while cold water or scalding water, which is water having an improper temperature, is drained from a drain port different from the shower head. In this case, a user does not feel uncomfortable due to cold water or scalding water being suddenly drained from the shower head.  
      However, in the above described channel switching valve, the user cannot intentionally cause water having an improper temperature to be drained from the shower head. For example, if cold water is required in the summer or if scalding water is required in the winter, the user cannot cause cold water or scalding water to be drained from the shower head.  
      In order to resolve such a problem, Patent Document 2 discloses an improved shower system which can drain not only water having a proper temperature, but also water having an improper temperature as required, from a shower head. The shower system comprises a relief mechanism for water having an improper temperature which inhibits water having an improper temperature to be drained from the shower head, a bypass channel provided so as to bypass the relief mechanism, and a switching valve for opening or closing the bypass channel. In this shower system, when a user desires to allow water having an improper temperature to be drained from the shower head, he/she may open the bypass channel by operating the switching valve. In this way, water having an improper temperature is drained from the shower head through the bypass channel, without passing through the relief mechanism.  
      However, in the shower system in Patent Document 2, it is required that a channel for draining water having a proper temperature from the shower head and a channel (the above described bypass channel) for draining water having an improper temperature from the shower head be separately provided. Therefore, this shower system is relatively large and requires a large installation space. Thus, if the space in a bath is small, the shower system cannot be installed.  
      Patent Document 1: Japanese Patent Laid-Open No. 10-299926  
      Patent Document 2: Japanese Patent Laid-Open No. 2003-=b  24232   
     DISCLOSURE OF THE INVENTION  
      It is a purpose of the present invention to provide a more compact channel switching valve which can drain not only fluid having a proper temperature, but also fluid having an improper temperature as required through a drain port for draining fluid having proper temperature. It is also a purpose of the present invention to provide a shower system comprising such a channel switching valve.  
      To achieve the above described purposes, in one aspect of the present invention, a channel switching valve is provided. The channel switching valve includes a valve casing, a valve body, and valve body activating means. The valve casing includes a fluid supply port for supplying fluid into the valve casing, a first drain port for draining fluid having a temperature out of a predetermined temperature range, which is supplied into the valve casing through the fluid supply port, a second drain port for draining fluid having a temperature in the predetermined temperature range, which is supplied into the valve casing through the fluid supply port, a first channel connecting the fluid supply port to the first drain port, a second channel connecting the fluid supply port to the second drain port, a first valve hole provided in the middle of the first channel, a second valve hole provided in the middle of the second channel, a first valve seat provided corresponding to the first valve hole, and a second valve seat provided corresponding to the second valve hole. The valve body moves between a first position in which the valve body contacts the first valve seat to close the first valve hole and a second position in which the valve body contacts the second valve seat to close the second valve hole. The valve body activating means allows the valve body to be placed in the first position or the second position based on the temperature of the fluid. A part of the first channel and a part of the second channel are common. The channel switching valve further includes lock means which forcefully moves the valve body to the first position and holds the valve body in the first position.  
      In another aspect of the present invention, a shower system is provided. The shower system includes the above described channel switching valve, a hose and a shower head. The shower head is connected to a first drain port of the channel switching valve through the hose.  
      Also, the present invention provides another channel switching valve as described below. The channel switching valve includes a body in which a channel is formed through which fluid passes, a discharge hole which is opened in the body to supply the fluid to a subsequent element, a drain hole which is opened in the body to drain the fluid if the temperature of the fluid is out of a predetermined temperature range, a valve body which is accommodated in the channel and opens or closes either a part of the channel connecting to the discharge hole or a part of the channel connecting to the drain hole, a first temperature sensitive element which is accommodated in the channel so as to bias the valve body in a predetermined direction, and a bias spring and a second temperature sensitive element which are accommodated in the channel so as to bias the valve body in a direction opposite to the predetermined direction. Biasing forces of the first temperature sensitive element and the second temperature sensitive element individually change depending on the temperature of the fluid. If the temperature of the fluid is out of the predetermined temperature range, the valve body moves to allow the fluid to be drained from the drain hole due to the sum of the biasing force of the bias spring and the biasing force of the second temperature sensitive element being larger than the biasing force of the first temperature sensitive element. A handle for forcefully moving the valve body in the channel is connected to the valve body. By operating the handle, the valve body is moved to close the part of the channel connecting to the drain hole. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a diagrammatic view of a channel switching valve according to a first embodiment which is placed between a combination faucet and a shower head;  
       FIG. 2  is a cross sectional view of the channel switching valve shown in  FIG. 1  in a state of discharging water having a proper temperature from a discharge hole;  
       FIG. 3  is a cross sectional view of the channel switching valve shown in  FIG. 1  in a state of draining water having an improper temperature from a drain hole;  
       FIG. 4  is a cross sectional view of the channel switching valve shown in  FIG. 1  in a state of discharging water having an improper temperature from the discharge hole;  
       FIG. 5  is a cross sectional view of a channel switching valve according to a second embodiment in a state of discharging water having a proper temperature from the discharge hole;  
       FIG. 6  is a cross sectional view of a channel switching valve according to the second embodiment in a state of draining water having an improper temperature from the drain hole;  
       FIG. 7  is a cross sectional view of a channel switching valve according to the second embodiment in a state of discharging water having an improper temperature from the discharge hole;  
       FIG. 8  is an exploded perspective view showing a latch mechanism which alternately opens and closes the drain hole and the discharge hole of the channel switching valve according to the second embodiment;  
       FIG. 9  is a developed view of a part of the latch mechanism shown in  FIG. 8 ;  
       FIG. 10  is a cross sectional view of a channel switching valve according to a third embodiment in a state of discharging water having a proper temperature from the discharge hole;  
       FIG. 11  is a cross sectional view of a channel switching valve according to the third embodiment in a state of draining water having an improper low temperature from the drain hole;  
       FIG. 12  is a cross sectional view of a channel switching valve according to the third embodiment in a state of draining water having an improper high temperature from the drain hole;  
       FIG. 13  is a cross sectional view of a channel switching valve according to the third embodiment in a state of forcefully discharging water having an improper low temperature from the discharge hole;  
       FIG. 14  is a cross sectional view of a channel switching valve according to the third embodiment in a state of forcefully discharging water having an improper hot temperature from the discharge hole; and  
       FIG. 15  is a graph showing temperature characteristics of first and second wax thermoelements. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION  
      Now, a first embodiment of the present invention will be described with reference to the drawings.  
      As shown in  FIG. 1 , a channel switching valve A according to this embodiment is attached between a combination faucet  1  and a shower head  2  in a bathroom, for example. A supply tube  5  is connected to the combination faucet  1  which adjusts temperature and flow rate of water which is a fluid. The combination faucet  1  comprises a switching valve  4  such that the water, which is adjusted in temperature and flow rate, is selectively supplied to either the supply tube  5  or a water discharge tube  3  of the combination faucet  1  by operating the switching valve  4 . The supply tube  5  is linked to a hose  6  through the channel switching valve A. The shower head  2  is attached at a tip of the hose  6 . The channel switching valve A, the shower head  2  and the hose  6  constitute a shower system.  
      As shown in  FIG. 2 , the channel switching valve A comprises a hollow body  10 . A first opening hole  12  is provided in one end (a lower end in  FIG. 2 ) of the body  10 . A first lid member  24  is attached to the first opening hole  12 . The first lid member  24  comprises a hot water supply port  24   b  as a fluid supply port. In the other end (an upper end in  FIG. 2 ) of the body  10 , a second opening hole  13  is provided. A second lid member  25  is attached to the second opening hole  13 . The body  10 , the first lid member  24  and the second lid member  25  constitute a valve casing. The valve casing comprises a channel  11  therein. Water, which is supplied from the combination faucet  1  to the supply tube  5 , flows through the hot water supply port  24   b  into the channel  11 .  
      In a circumferential wall of the body  10 , a drain hole  15  as a first drain port and a discharge hole  14  as a second drain port are provided. If the temperature of the water from the combination faucet  1  is in a predetermined temperature range, i.e., if the water from the combination faucet  1  has a proper temperature, the water from the combination faucet  1  is discharged from the discharge hole  14 . If the temperature of the water from the combination faucet  1  is out of the predetermined temperature range, i.e., if the water from the combination faucet  1  has an improper temperature, the water from the combination faucet  1  is drained from the drain hole  15 . That is, the water from the combination faucet  1  is selectively discharged from the discharge hole  14  or drained from the drain hole  15 , depending on the temperature of the water. In this embodiment, a temperature higher than 35° C. and lower than 45° C. is a proper temperature while a temperature equal to or lower than 35° C. or equal to or higher than 45° C. is an improper temperature. The discharge hole  14  and the drain hole  15  are placed in mutually different positions with respect to the flow direction of the water flowing through the channel  11 . Specifically, the discharge hole  14  is located downstream in comparison with the drain hole  15 . Both the discharge hole  14  and the drain hole  15  link to the hot water supply port  24   b  through the channel  11 . That is, the channel  11  includes a first channel from the hot water supply port  24   b  to the drain hole  15  (an arrow with a two-dot chain line shown in  FIG. 3 ) and a second channel from the hot water supply port  24   b  to the discharge hole  14  (an arrow with a two-dot chain line shown in  FIG. 2 ), wherein a part of the first channel and a part of the second channel are common (overlapped).  
      A first valve hole  33   a  is provided in the midway of a section of the channel  11  from the hot water supply port  24   b  to the drain hole  15 . A second valve hole  33   b  is provided in the midway of a section of the channel  11  from the hot water supply port  24   b  to the discharge hole  14 . The first valve hole  33   a  and the second valve hole  33   b  are placed in mutually different positions with respect to the flow direction of the water flowing through the channel  11 . Specifically, the second valve hole  33   b  is located downstream in comparison with the first valve hole  33   a.    
      In the channel  11 , a generally cylindrical valve body  16  is accommodated. In the middle of an outer circumference of the valve body  16 , an annular groove  17  is provided which extends circumferentially. A seal member  18  is attached to the annular groove  17  so as to closely contact to an outer surface of the valve body  16  and an inner surface of the channel  11 .  
      The valve body  16  has a first annular end face  19   a  which is located adjacent to the first lid member  24  on one end (a lower end in  FIG. 2 ) and a second annular end face  19   b  which is located adjacent to the second lid member  25  on the other end (an upper end in  FIG. 2 ). The valve body  16  can move between a first position P 1  shown in  FIG. 2  where the first end face  19   a  of the valve body  16  contacts an upper end face of the first lid member  24  which acts as a first valve seat  24   a,  and a second position P 2  shown in  FIG. 3  where the second end face  19   b  of the valve body  16  contacts a lower end face of the second lid member  25  which acts as a second valve seat  25   a.  When the valve body  16  is in the first position P 1 , the second valve hole  33   b  is opened as shown in  FIG. 2 . Therefore, the water from the combination faucet  1  is discharged from the discharge hole  14 . On the other hand, when the valve body  16  is in the second position P 2 , the first valve hole  33   a  is opened as shown in  FIG. 3 . Therefore, the water from the combination faucet  1  is drained from the drain hole  15 .  
      In the channel  11 , there are accommodated a first temperature sensitive element  23   a  which biases the valve body  16  toward the first position P 1  (toward the downstream side) and a second temperature sensitive element  23   b  and a bias spring  22  which bias the valve body  16  toward the second position P 2  (toward the upstream side). The first temperature sensitive element  23   a  and the second temperature sensitive element  23   b  are coil springs made of shape memory alloy and transform so as to expand or contract in an axial direction depending on the temperature of the water from the combination faucet  1 . The first temperature sensitive element  23   a,  which is located downstream (upside in  FIG. 2 ) in comparison with the valve body  16 , expands if the temperature of the water from the combination faucet  1  is in the predetermined temperature range. The second temperature sensitive element  23   b,  which is located upstream (downside in  FIG. 2 ) in comparison with the valve body  16 , expands if the temperature of the water from the combination faucet  1  is in a different temperature range from the above described predetermined temperature range. Thus, biasing forces of the first temperature sensitive element  23   a  and the second temperature sensitive element  23   b  individually change depending on the temperature of the water from the combination faucet  1 . On the other hand, biasing force of the bias spring  22  placed in the second temperature sensitive element  23   b  is independent of the temperature of the water from the combination faucet  1 . The bias spring  22 , the first temperature sensitive element  23   a  and the second temperature sensitive element  23   b  constitute valve body actuating means, which allows the valve body  16  to be placed in the first position P 1  or the second position P 2  based on the temperature of the water from the combination faucet  1 .  
      One end (a lower end in  FIG. 2 ) of the first temperature sensitive element  23   a  contacts a collar part  20  which is provided in the middle of the inner circumference of the valve body  16 . The other end (an upper end in  FIG. 2 ) of the first temperature sensitive element  23   a  contacts a plug  28  which is threadably engaged with the second lid member  25 . One end (an upper end in  FIG. 2 ) of the bias spring  22  and the second temperature sensitive element  23   b  contacts the collar part  20 . The other end (a lower end in  FIG. 2 ) of the bias spring  22  and the second temperature sensitive element  23   b  contacts the first lid member  24 .  
      If the temperature of the water passing through the channel  11  is equal to or lower than 35° C., neither of the first and second temperature sensitive elements  23   a,    23   b  extend. In this case, load applied to the valve body  16  by the first temperature sensitive element  23   a  is smaller than load applied to the valve body  16  by the bias spring  22  and the second temperature sensitive element  23   b.  In other words, the biasing force of the first temperature sensitive element  23   a  which biases the valve body  16  toward the upstream side (downside in  FIG. 2 ) is smaller than the sum of the biasing force of the bias spring  22  and the biasing force of the second temperature sensitive element  23   b  which bias the valve body  16  toward the downstream side (upside in  FIG. 2 ). Therefore, the valve body  16  moves upwardly to be placed in the second position P 2  as shown in  FIG. 3 .  
      If the temperature of the water passing through the channel  11  is equal to or higher than 45° C., only the second temperature sensitive element  23   b  extends and the first temperature sensitive element  23   a  does not extend. Also in this case, the biasing force of the first temperature sensitive element  23   a  which biases the valve body  16  downwardly is smaller than the sum of the biasing force of the bias spring  22  and the biasing force of the second temperature sensitive element  23   b  which bias the valve body  16  upwardly. Therefore, the valve body  16  moves upwardly to be placed in the second position P 2 .  
      If the temperature of the water passing through the channel  11  is higher than 35° C. and lower than 45° C., only the first temperature sensitive element  23   a  extends and the second temperature sensitive element  23   b  does not extend. In this case, the load applied to the valve body by the first temperature sensitive element  23   a  is larger than the load applied to the valve body  16  by the bias spring  22  and the second temperature sensitive element  23   b.  In other words, the biasing force of the first temperature sensitive element  23   a  which biases the valve body  16  downwardly is larger than the sum of the biasing force of the bias spring  22  and the biasing force of the second temperature sensitive element  23   b  that bias the valve body  16  upwardly. Therefore, the valve body  16  moves downwardly to be placed in the first position P 1  as shown in  FIG. 2 .  
      The second lid member  25  is generally cylindrical in shape and has a through hole  26  which extends in an axial center direction. On an inner circumferential surface of the through hole  26 , an internally threaded part  27  is provided. The plug  28  has an externally threaded part  29  corresponding to the internally threaded part  27 . A part of the plug  28  is inserted in the through hole  26  with the externally threaded part  29  of the plug  28  engaged with the internally threaded part  27  of the second lid member  25 . A handle  31  is connected to a tip of the plug  28 . The plug  28  has an annular support part  30  on its inner circumference and the upper end of the first temperature sensitive element  23   a  contacts the support part  30 . When the handle  31  is rotated so that the plug  28  is threaded into the second lid member  25  or the plug  28  moves downwardly, the valve body  16  moves to the first position P 1  and is held in that position. The plug  28  and the handle  31  constitute lock means which moves the valve body  16  forcefully to the first position P 1  and holds the valve body  16  in the first position P 1 .  
      Then, an operation of the channel switching valve A will be described.  
      If the temperature of water supplied from the combination faucet  1  to the channel switching valve A is higher than 35° C. and lower than 45° C., only the first temperature sensitive element  23   a  extends and the second temperature sensitive element  23   b  does not extend. Therefore, as shown in  FIG. 2 , the valve body  16  moves downwardly to be placed in the first position P 1  by the biasing force of the first temperature sensitive element  23   a  being larger than the sum of the biasing force of the bias spring  22  and the biasing force of the second temperature sensitive element  23   b.  As a result, the first end face  19   a  of the valve body  16  is located on (contacts) the first valve seat  24   a  of the first lid member  24  so that the first valve hole  33   a  is closed. Therefore, the water in the channel  11  is discharged from the discharge hole  14  through the second valve hole  33   b  and supplied to the hose  6 . In this way, the water having a proper temperature higher than 35° C. and lower than 45° C. is discharged from the shower head  2 .  
      If the temperature of water supplied from the combination faucet  1  to the channel switching valve A is equal to or lower than 35° C., neither of the first and second temperature sensitive elements  23   a,    23   b  extends. Therefore, as shown in  FIG. 3 , the valve body  16  moves upwardly to be placed in the second position P 2  by the biasing forces of the bias spring  22  and the second temperature sensitive element  23   b  being larger than the biasing force of the first temperature sensitive element  23   a.  As a result, the second end face  19   b  of the valve body  16  is located on (contacts) the second valve seat  25   a  of the second lid member  25  so that the second valve hole  33   b  is closed. Therefore, through the first valve hole  33   a,  the water in the channel  11  is drained from the drain hole  15  to the outside. Thus, water having an improper temperature equal to or lower than 35° C. is not discharged from the shower head  2 .  
      If the temperature of water supplied from the combination faucet  1  to the channel switching valve A is equal to or higher than 45° C., only the second temperature sensitive element  23   b  extends and the first temperature sensitive element  23   a  does not extend. Therefore, as shown in  FIG. 3 , the valve body  16  moves upwardly to be placed in the second position P 2  by the biasing forces of the bias spring  22  and the second temperature sensitive element  23   b  being larger than the biasing force of the first temperature sensitive element  23   a.  As a result, the second end face  19   b  of the valve body  16  is located on (contacts) the second valve seat  25   a  of the second lid member  25  so that the second valve hole  33   b  is closed. Therefore, through the first valve hole  33   a,  the water in the channel  11  is drained from the drain hole  15  to the outside. Thus, the water having an improper temperature equal to or higher than 45° C. is also not discharged from the shower head  2 .  
      If it is desired that water having an improper temperature equal to or lower than 35° C. or equal to or higher than 45° C. be discharged from the shower head  2 , the handle  31  is rotated so that the plug  28  moves downwardly. Thereby, the first temperature sensitive element  23   a  is compressed by the plug  28  such that the valve body  16  is downwardly biased through the first temperature sensitive element  23   a  to move to the first position P 1 , as shown in  FIG. 4 . As a result, the first end face  19   a  of the valve body  16  is located on the first valve seat  24   a  of the first lid member  24  so that the first valve hole  33   a  is closed. Spring force of the first temperature sensitive element  23   a,  which is enhanced by the compression, is enough large to continue to hold the valve body  16  in the first position P 1 , even if the second temperature sensitive element  23   b  extends. Therefore, the water from the combination faucet  1  is not drained from the drain hole  15 , but discharged from the discharge hole  14 . In this way, not only water having a proper temperature, but also water having an improper temperature as required can be discharged from the discharge hole  14 .  
      This embodiment has following advantages.  
      (1) In the channel switching valve A shown in  FIG. 1 , a part of the first channel for draining water having a proper temperature from the shower head  2  and a part of the second channel for draining water having an improper temperature from the shower head  2  are common. Therefore, the channel switching valve A is compact in comparison with the case in which the first channel and the second channel is completely separately provided.  
      (2) Even if water having an improper temperature flows in the channel  11 , the valve body  16  moves to the first position P 1  by rotating the handle  31 . Therefore, water having an improper temperature can be discharged from the shower head  2 , as required.  
      (3) The first and second temperature sensitive elements  23   a,    23   b  made of shape memory alloy extend or contract depending on the temperature of water from the combination faucet  1 , which allows the valve body  16  to move without relying on electrical power. Therefore, the channel switching valve A can be installed when installation space permits, even in a place where no power supply is provided. Further, because a power supply is not required, a structure for preventing electrical leakage is unnecessary in the channel switching valve A. This contributes to downsizing and low cost of the channel switching valve A. In addition, by using the first temperature sensitive element  23   a  and the second temperature sensitive element  23   b  which allow the valve body  16  to move without relying on electrical power, no actuation noise is generated when the valve body  16  is moved.  
      (4) Because the valve body  16  is placed in the channel  11  in the valve casing, space saving for the body  10  may be realized so that the channel switching valve A can be more compact.  
      (5) Because the valve body  16  is shaped like a tube in order to guide water flowing from the hot water supply port  24   b  to the discharge hole  14 , weight reduction of the valve body  16  may be realized. As a consequence, responsivity improves when the valve body  16  moves and thus it is possible to speed up the open/close switching of the discharge hole  14  and the drain hole  15 . Also, the weight reduction of the valve body  16  contributes to weight reduction of the channel switching valve A.  
      Next, a second embodiment of the present invention will be described with reference to the drawings. Points which are different from the first embodiment will now be mainly described and the same or similar components will be designated by the same reference symbol as in the first embodiment and description of the components will be omitted.  
      As shown in  FIG. 5  and  FIG. 8 , a tube body  38  is threadably engaged with the second lid member  25  of the channel switching valve A. In an inner circumferential surface of the tube body  38 , three protruding strips  39  are formed at even intervals to extend in an axial direction. Vertical grooves  40  are formed between these protruding strips  39 . On an end of each protruding strip  39 , respective sawtooth surface  41  is formed. With the sawtooth surfaces  41 , stopper parts  42  are formed so as to be located in the middle part between adjacent vertical grooves  40 .  
      In the tube body  38 , an operating shaft  43  is inserted to project from an upper end face of the tube body  38 . A handle  31  is attached to an upper end of the operating shaft  43 . A support hole  44  is formed in the middle of a lower end of the operating shaft  43 . A flange part  45  is formed on an outer circumference of the lower end of the operating shaft  43 . A coil spring  46  is provided between the flange part  45  of the operating shaft  43  and the tube body  38 . Due to biasing force of the coil spring  46 , the operating shaft  43  is outwardly biased.  
      On an outer circumferential surface of the flange part  45  of the operating shaft  43 , three engaging protrusions  47  are provided at even intervals. On an end face of the flange part  45 , six gable cam faces  48  are formed at even intervals. The operating shaft  43  can move in the axial direction of the tube body  38  by each engaging protrusion  47  of the operating shaft  43  slidably engaging with a respective vertical groove  40  of the tube body  38 .  
      In the support hole  44  of the operating shaft  43 , a rotatable body  49  is inserted and supported so that it can relatively rotate and relatively move in the axial direction. A flange part  50  is formed on the middle outer circumference of the rotatable body  49 . On an outer circumferential surface of the flange part  50 , three engaging protrusions  51  are provided at even intervals, which can engage to the vertical grooves  40  of the tube body  38  and the stopper parts  42 . On an end face of the flange part  50  which opposes to the flange part  45  on the above described operating shaft  43 , six inclined faces  52  are formed at even intervals, which can engage with the gable cam faces  48  of the operating shaft  43 .  
      In a lower end in the tube body  38 , the rotatable body  49  is inserted and supported so that it can move through a support tube  54  in the axial direction. A tip of the rotatable body  49  is placed in the channel  11  through the through hole  53  (see  FIG. 7 ) formed in the second lid member  25  and can contact a pressure plate  56  which is put on an end of the first temperature sensitive element  23   a.  A pressure spring  55  is fitted on the rotatable body  49 . One end of the pressure spring  55  is fixed to the flange part  50  of the rotatable body  49  and the other end is fixed to the support tube  54 . The rotatable body  49  is biased by the pressure spring  55  to outwardly move, such that the inclined faces  52  of the rotatable body  49  are engaged with the gable cam faces  48  of the operating shaft  43 .  
      An operation of the channel switching valve A in this embodiment will be described.  
      As shown in  FIG. 5 , when water having a proper temperature is supplied from the combination faucet  1  to the body  10  of the channel switching valve A in a state in which the tip of the rotatable body  49  is separated from the pressure plate  56  and the first temperature sensitive element  23   a  is not forcefully compressed from the outside, the valve body  16  is moved to the first position Pi so that the first end face  19   a  of the valve body  16  is seated on (contacts) the first valve seat  24   a  in the first lid member  24 . As a result, linkage between the channel  11  and the drain hole  15  is blocked while linkage between the channel  11  and the discharge hole  14  is allowed and thus water having a proper temperature is discharged from the discharge hole  14 .  
      As shown in  FIG. 6 , when water having an improper temperature is supplied from the combination faucet  1  to the body  10  of the channel switching valve A in a state in which the tip of the rotatable body  49  is separated from the pressure plate  56  and the first temperature sensitive element  23   a  is not forcefully compressed from the outside, the valve body  16  is moved to the second position P 2  so that the second end face  19   b  of the valve body  16  is seated on the second valve seat  25   a  in the second lid member  25 . As a result, the discharge hole  14  is closed while the drain hole  15  is opened and thus water having a proper temperature is drained from the drain hole  15 .  
      Then, a case will be described when water having an improper temperature flowing in the channel  11  of the body  10  is forcefully discharged from the discharge hole  14 . When pushing the handle  31 , the operating shaft  43  moves downwardly against biasing force of the coil spring  46  and the rotatable body  49  moves in the same direction. In this case, with movement of the operating shaft  43 , the rotatable body  49  is rotated by a predetermined angle by engagement of the gable cam faces  48  and the inclined faces  52  such that the engaging protrusions  51  on the rotatable body  49  get out of the vertical grooves  40  of the tube body  38  and are engaged with the stopper parts  42 , as shown in  FIG. 9 .  
      Therefore, even if the pushing operation of the handle  31  is released in this state, the rotatable body  49  is held in the lower position, although the handle  31  and the operating shaft  43  is moved to return to the upper position by the biasing force of the coil spring  46 . Thus, as shown in  FIG. 7 , the first temperature sensitive element  23   a  is kept in a compressed state by the pressure plate  56  while the valve body  16  is forcefully moved to the first position P 1 . In this state, even if load generates on either of the temperature sensitive elements  23   a,    23   b,  the valve body  16  does not return to the second position P 2  because a large biasing force applies to the valve body  16  by compression of the first temperature sensitive element  23   a.  Therefore, the second valve hole  33   b  is kept opened and water having an improper temperature continues to be discharged from the discharge hole  14 .  
      When pushing the handle  31  once again, the operating shaft  43  moves downwardly so that the rotatable body  49  is further rotated by a predetermined angle by engagement of the gable cam faces  48  and the inclined faces  52 . As a result, the engaging protrusions  51  on the rotatable body  49  come off the stopper parts  42  of the tube body  38  and are inserted to engage into the vertical grooves  40 . When the pushing operation of the handle  31  is subsequently released, the handle  31  and the operating shaft  43  move to return to the upper position by the biasing force of the coil spring  46  while the rotatable body  49  moves to return to the lower position due to the biasing force of the pressure spring  55 .  
      As a result, as shown in  FIG. 6 , the pressure plate  56  is released from the pressure condition and the valve body  16  is moved to the second position P 2  by the biasing forces of the bias spring  22  and the second temperature sensitive element  23   b.  However, because water having an improper temperature has flowed into the channel  11 , the valve body  16  remains to be placed in the second position P 2  and the first valve hole  33   a  is kept opened. Therefore, water having an improper temperature is drained from the drain hole  15 .  
      Thus, each pushing operation of the handle  31  can alternately switch between a locked state in which the actions of the both temperature sensitive elements  23   a,    23   b  and the bias spring  22  are deactivated by holding the valve body  16  in the first position P 1  and an unlocked state in which their actions are activated by releasing the hold of the valve body  16 . Therefore, one-touch switching is possible in comparison with the case of switching between the locked state and the unlocked state by rotating the handle  31  as shown in  FIG. 1 .  
      In this embodiment, the plug  28 , the handle  31 , the operating shaft  43 , the rotatable body  49 , the pressure spring  55  and the pressure plate  56  constitute lock means.  
      Then, a third embodiment of the present invention will be described with reference to the drawings. Points which are different from the first embodiment will now be mainly described and the same or similar components will be designated by the same reference symbol as in the first embodiment and description of the components will be omitted.  
      As shown in  FIG. 10 , a tube-like accommodating case  60  is provided between the body  10  and the first lid member  24 . In the accommodating case  60 , a first wax thermoelement  61  as a first temperature sensitive element and a second wax thermoelement  62  as a second temperature sensitive element are accommodated, which are spaced in the upstream side and the downstream side of the accommodating case  60 . Each wax thermoelement  61 ,  62  comprises a piston rod  61   a,    62   a  which changes its projecting amount as a function of the volume of wax varying with the temperature of shower water. In addition, in this embodiment, a valve casing is constituted by the body  10 , the first lid member  24  and the second lid member  25 .  
      The piston rods  61   a,    62   a  of the wax thermoelements  61 ,  62  are pointed in opposite directions to each other. A tip of the piston rod  62   a  of the second wax thermoelement  62 , which is pointed downward, is supported in the middle part of the first lid member  24  through which shower water can pass. A guide tube  62   b  for guiding the piston rod  62   a  is formed near the middle of the accommodating case  60 . The guide tube  62   b  is slidably inserted into the center of the guide part  63  through which shower water can pass. Therefore, the second wax thermoelement  62  is supported so that it can move upwardly and downwardly.  
      On a top of the second wax thermoelement  62 , the first wax thermoelement  61  is supported through the bias spring  22 . The wax thermoelements  61 ,  62  can move close to or away from each other. A guide tube  61   b  which guides the piston rod  61   a  of the first wax thermoelement  61  is threaded to the middle part of the above described valve body  16 . Therefore, the first wax thermoelement  61  and the valve body  16  move together. Valve body activating means is constituted by the bias spring  22 , the first wax thermoelement  61  and the second wax thermoelement  62 .  
      In this embodiment, the first valve seat  64   a,  to which the first end face  19   a  of the valve body  16  contacts when the valve body  16  is placed in the first position P 1 , is an end of the accommodating case  60 . Further, the second valve seat  64   b,  to which the second end face  19   b  of the valve body  16  contacts when the valve body  16  is placed in the second position P 2 , is a circumference of the valve seat  66  which is attached by a pinching member  65  threadably engaged with the second lid member  25 . In the middle part of the pinching member  65 , a rod support part  16   a  is slidably inserted, which is provided to protrude from the middle part of the valve body  16 . The purpose of arrangement in this way is to stably move the valve body  16 , to which the first wax thermoelement  61  is attached, between the first position P 1  and the second position P 2 .  
      A plug  67 , to which the handle  31  is integrally attached, is threaded to the above described second lid member  25  so that the plug  67  can move forward and backward. A relief coil spring  68  is accommodated in an internal space  67   a  of the plug  67 . One end of the relief coil spring  68  abuts the inner part of the internal space  67   a  and the other end is engaged with the moving body  70  provided on an adjuster  69  which is threaded to a lower end face of the plug  67 . The relief coil spring  68  is set to have a spring constant larger than that of the bias spring  22  and biasing force of the relief coil spring  68  can be also adjusted by changing the threaded position of the adjuster  69 . In a through hole  69   a  formed in the middle part of the adjuster  69 , a tip of the piston rod  61   a  of the first wax thermoelement  61  is inserted so that the tip can contact the moving body  70 .  
      Temperature characteristics of each of the above described wax thermoelements  61 ,  62  will be described. The piston rods  61   a,    62   a  of the wax thermoelements  61 ,  62 , respectively, are set to have different projecting amounts depending on the temperature of shower water. That is, as shown in  FIG. 15 , when the temperature of shower water is lower than 45° C., the projecting amount of the piston rod  61   a  of the first wax thermoelement  61  is larger than the projecting amount of the piston rod  62   a  of the second wax thermoelement  62 . When the temperature of shower water is higher than 45° C., the projecting amount of the second piston rod  62   a  is larger than the projecting amount of the first piston rod  61   a.  In addition, the piston rod  61   a  of the first wax thermoelement  61  is set to have the largest projecting amount and reach its stroke end when the temperature of shower water is 45° C. On the other hand, the piston rod  62   a  of the second wax thermoelement  62  is set to reach its stroke end when the temperature of shower water is higher than 45° C.  
      Therefore, as shown in  FIG. 10 , when water having a proper temperature flows into the channel  11  of the channel switching valve A, the piston rod  61   a  of the first wax thermoelement  61  hits against the moving body  70  before reaching its stroke end and reaches the stroke end in that state. Then, since the spring constant of the relief coil spring  68  is set to be larger than that of the bias spring  22 , the first wax thermoelement  61  moves, due to thrust (load) of the piston rod  61   a,  in the opposite direction to the protrusion direction of the piston rod  61   a  so as to compress the bias spring  22  and therefore the valve body  16  is placed in the first position P 1 . As a result, the first valve hole  33   a  is closed while the second valve hole  33   b  is opened and thus water having a proper temperature flowing into the channel  11  is discharged from the discharge hole  14  through the second valve hole  33   b.    
      As shown in  FIG. 11 , when water having an improper temperature equal to or lower than 35° C. flows into the channel  11  of the channel switching valve A, the piston rod  61   a  of the first wax thermoelement  61  does not hit against the moving body  70  and therefore the valve body  16  is placed in the second position P 2  by elastic force of the bias spring  22 . As a result, the second valve hole  33   b  is closed while the first valve hole  33   a  is opened and thus water having a proper temperature flowing into the channel  11  is drained from the drain hole  15  through the first valve hole  33   a.    
      As shown in  FIG. 12 , when water having an improper temperature equal to or higher than 45° C. flows into the channel  11  of the channel switching valve, upward thrust (load) is provided by only the piston rod  62   a  of the second wax thermoelement  62  after the piston rod  61   a  of the first wax thermoelement  61  has reached its stroke end, such that the bias spring  22  is further compressed and the biasing force of the bias spring  22  becomes larger than the biasing force of the relief coil spring  68 . Therefore, the first wax thermoelement  61  is pushed upwardly so that the valve body  16  is placed in the second position P 2 . As a result, the second valve hole  33   b  is closed while the first valve hole  33   a  is opened and thus water having an proper temperature flowing into the channel  11  is drained from the drain hole  15  through the first valve hole  33   a.    
      Then, a case will be described when water having an improper temperature flowing in the channel  11  is forcefully discharged from the discharge hole  14 . When water having an improper temperature equal to or lower than 35° C. flows into the channel  11  of the channel switching valve A shown in  FIG. 11 , by rotating the handle  31  to tighten, the plug  67  rotates and approaches the first wax thermoelement  61  and the moving body  70  hits against the tip of the piston rod  61   a,  as shown in  FIG. 13 . When the moving body  70  is further moved in this state, the whole first wax thermoelement  61  is pushed downwardly against the biasing force of the bias spring  22 , so that the valve body  16  is forcefully moved to the first position P 1 . As a result, the first valve hole  33   a  is forcefully closed while the second valve hole  33   b  is opened and thus water having an improper temperature is discharged from the discharge hole  14  to the side of the shower head  2 , even though water having an improper temperature flows in the channel  11 .  
      When water having an improper temperature equal to or higher than 45° C. flows into the channel  11  of the channel switching valve A shown in  FIG. 12 , by rotating the handle  31  to tighten it, the valve body  16  is forcefully placed in the first position P 1  while keeping the state in which the tip of the piston rod  61   a  of the first wax thermoelement  61  hits against the moving body  70 , as shown in  FIG. 14 . As a result, the first valve hole  33   a  is forcefully closed while the second valve hole  33   b  is opened and thus water having an improper temperature is discharged from the discharge hole  14  to the side of the shower head  2 , even though water having an improper temperature flows in the channel  11 .  
      Therefore, even if the valve body  16  is placed in the first position P 1  due to assembly errors of the first wax thermoelement  61  or the like, when the piston rod  61   a  of the first wax thermoelement  61  has not reached its stroke end and has some space for further projection, projection of the piston rod  61   a  is permitted by the relief coil spring  68  being compressed. Therefore, it is possible to prevent a large extraction force from being applied a joint portion of the first wax thermoelement  61  and the valve body  16  and to achieve enhanced reliability. At the same time, the first valve hole  33   a  and the second valve hole  33   b  can be successfully opened and closed without being affected by assembly accuracy of the first wax thermoelement  61 .  
      The above described embodiments may be modified as follows.  
      In the first and second embodiments, the first temperature sensitive element  23   a  may be placed inside the bias spring  22 , instead of being placed outside the bias spring  22 . The first and second temperature sensitive elements  23   a,    23   b  may be plate springs, wires or the like, instead of coil springs.  
      Although, in the first and second embodiments, the first temperature sensitive element  23   a  extends when the temperature of shower water is higher than 35° C. and lower than 45° C. and the second temperature sensitive element  23   b  extends when the temperature of shower water is equal to or higher than 45° C., other temperature sensitive elements may be used which extend in different temperature regions from the above described temperature and also the temperature range in which water is considered to have a proper temperature may be changed. Also in the third embodiment, the temperature range in which water is considered to have a proper temperature may be changed by changing temperature characteristics for projection of the piston rods  61   a,    62   a  of the respective wax thermoelement  61 ,  62 .  
      Although, in the above described first to third embodiments, the valve body  16  is mechanically moved between the first position P 1  and the second position P 2  with the temperature sensitive elements  23   a,    23   b  of shape memory alloy or the wax thermoelements  61 ,  62 , the valve body  16  may be electrically moved with solenoid valves or the like, for example. In this case, a temperature sensor is provided on the body  10  in order to actuate the solenoid valves based on temperature sensing signals which are detected by the temperature sensors.  
      Although, in the above described embodiments, the second drain port for draining water having an improper temperature is provided in the upstream side of the channel and the first drain port for draining water having a proper temperature is provided in the downstream side, the positional relationship of the first and second drain ports may be changed.  
      A fluid is not limited to water (shower water) and it may be other liquid such as lubricating oil or gas such as air, for example.  
      The channel switching valve A may be applied to a warm-water bidet, for example, instead of a shower system in a bath.