HK1011395B - An inlet valve mechanism - Google Patents

Description

The present invention relates to interlock mechanisms for cisterns and, in particular, to cisterns having a flush valve.

Cisterns (or flush tanks as they are known in the USA) can be conveniently categorised into two types. One type of cistern has a flush valve located in its base which is used to block the flush pipe which connects the cistern to the pan. The flush valve is analogous to the plug in a sink or basin which is full of water. When the flush valve is operated, this is equivalent to the plug being removed, and the water in the cistern flows through the flush valve and down the flush pipe. Cisterns of this type are for example disclosed in US-A- 5211204, EP-A- 0182663 and DE-C- 364423.

The other type of cistern is the syphonic cistern in which the flush pipe is connected with the interior of the cistern via an inverted U-shaped passage which at its highest point passes above the maximum water level in the cistern. In order for such a cistern to be flushed it is necessary for the U-shaped passage to be filled with water and thereby induce a syphonic action within the passage which syphons the water from the cistern into the flush pipe.

The cistern incorporating the flush valve suffers from the problem that the flush valve, particularly after a number of years of service, may commence leaking. Such leaking can be brought about because of a number of reasons such as algae growth on the valve, debris which has been introduced into the cistern via the inlet pipe becoming lodged in the flush valve, the perishing of rubber components of the flush valve, and the like. Normally such leaking is not catastrophic, instead there is a trickle of water down the flush pipe and into the lavatory pan.

All cisterns must be provided with a re-filling mechanism which normally takes the form of an inlet valve connected a mains water supply in which the water is under pressure, and a level detecting arrangement which opens the inlet valve when the water level within the cistern drops, and closes the inlet valve when the water level within the cistern rises to its predetermined "full" height or level. The level detecting arrangement is almost universally a float which is connected to the inlet valve by means of a pivoting float arm.

Because of the inlet valve and its float, as water trickles from a cistern with a leaking flush valve, the float drops slightly within the cistern thereby allowing a volume of water to enter the cistern and the level of water within the cistern to be brought back to the full level. This intermittent repetitive operation of the inlet valve keeps the cistern full of water and ready to be flushed on the next occasion when it is required to be used. As a consequence, although the leaking trickle of water into the pan may well be obvious to the persons using the cistern, such a trickle is universally ignored. Even the most vigilant of users is likely to regard such a trickle as merely a precursor which indicates that in many months time some maintenance action may be required in relation to the cistern.

It is well known that cisterns with leaking flush valves waste considerable amounts of water and that in this connection a cistern having a flush valve is very different from the syphonic cistern which is inherently non-leaking. This is because once the flush finishes and the syphonic action is broken, the interconnection between the water in the cistern and the flush pipe includes a passage which lies above the level of water in the cistern and thus no leak is possible. Instead, a deliberate measure must be taken in order to re-commence the syphonic action.

Because of the possibility of cisterns with flush valves wasting large volumes of water, in many jurisdictions cisterns with flush valves are prohibited by law or regulation. Hong Kong is one such jurisdiction where this regulatory regime arises because of historical problems regarding the uncertainty of water supplies.

However, in recent years many advances have been made in relation to flush valve cisterns, particularly in relation to dual flush cisterns which utilise very small volumes of water for a full and half flush (typically 6 and 3 litres respectively). Such dual flush cisterns have found favour with water supply authorities since they enable the volume of water consumed to be substantially reduced. Any saving in water usage is quickly reflected in an ability to defer capital works regarding the construction of additional reservoirs, dams and the like.

In view of the above identified problems of flush valve systems US-A-5 211 204 and EP-A-0 182 663 propose mechanisms which are capable of reducing the maximum value of water which can be waisted if the flush valve should happen to leak to the volume of water contained within the system. The flush valve system according to US-A- 5 211 204 comprises an interlock mechanism according to the features of the preamble of claim 1.

It is the object of the present invention to provide further improved flush valve operated systems of the type disclosed in US-A-5 211 204 and a further improved method of operating the same. With this respect an interlock mechanism for a flush valve operated cistern as specified in appended claim 1 and a method of operating a flush valve operated cistern as specified in appended claim 3 are proposed.

A basic embodiment of the present invention will now be described with reference to the drawings in which:

• Fig. 1 is a side elevational view of the interior of a flush valve operated cistern utilising the basic embodiment,
• Fig. 2 is a close up side elevational view of the top of the flush mechanism in the latch set position,
• Fig. 3 is a view similar to Fig. 2 but showing release of the latch, and
• Fig. 4 is a view similar to Figs. 2 and 3 but showing re-setting of the latch.

The basic embodiment of the present invention will now be described. Here the cistern 1 has a flush valve 3, and inlet stem 4, flush actuator buttons 10 and flush mechanism 11 substantially as before. However, mounted atop the inlet stem 4 is a conventional inlet valve 50 having a conventional float arm 57 and float 56.

The flush valve 3 is provided with a hollow rectangular float stem 38, the lower portion of which is illustrated in Fig. 1 and the upper portion of which is illustrated in Fig. 2. The hollow float stem 38 functions as an overflow tube in conventional manner. Straddling the flush mechanism 11 and passing over the top of the float stem 38 is a saddle 40 on which is pivoted a downwardly directed cup 41. The cup 41 is pivoted on the saddle 40 by means of an L-shaped arm 42. Secured to the saddle 40 is an erect upstand 43 which includes a lip 44 which provides a flat surface or step. Pivoted from the float arm 57 is a pendulous stay 45 which includes a notch 46 towards its middle and a ramp 47 at its lower end.

In the initial position illustrated in Fig. 2 in which the cistern is full, the stay 45 is substantially vertical and the notch 46 is engaged with the lip 44. As a consequence, the float arm 57 is immobilised and unable to drop should the water level within the cistern fall.

As indicated in Fig. 3, in the event that one of the actuator buttons 10 (Fig. 1) is depressed, then the conventional flush mechanism 11 raises the float stem 38 in order to open the flush valve 3. The upward movement of the float stem 38 moves the upper lip of the float stem 38 along the ramp 47 thereby tilting the stay 45 in an anti-clockwise direction to the position shown in Fig. 2. This disengages the notch 46 and lip 44 thereby allows the float arm 57 to pivot in an anti-clockwise direction as seen in Fig. 3. This allows the inlet valve 50 to permit water to enter the cistern 1 in order to refill the cistern. The fall and subsequent rise of water within the cistern 1 means that the downwardly directed cup 41 which functions as a float permits the L-shaped arm 42 to firstly pivot in a clockwise direction as the water level falls. and then pivot in an anti-clockwise direction as the water level rises. Since the stay 45 and lip 44 of the upstand 43 are disengaged during this period, the movement of the L-shaped arm 42 is of no effect.

From the position illustrated in Fig. 2, if the flush valve 3 should happen to leak slowly, then the cup 41 falls slowly with the falling water level until it reaches essentially the position illustrated in Fig. 4. In this position, the pivoted end of the L-shaped arm 42 lies against the stay 45. As the stay 45 is in the position illustrated in Fig. 2, the arm 42 urges the notch 46 into firmer engagement with the lip 44. As a consequence, notwithstanding the fall in the level of water within the cistern 1, the float arm 57 does not fall and the water is allowed to enter the cistern 1. This position is stable and remains so until the next occasion on which either one of the flush actuator buttons 10 is depressed thereby raising the float stem 38.

When the float stem 38 is raised, the stay 45 is again jolted by the upper lip of the float stem 38 so as to disengage the notch 46 and lip 44. In this way the latch in the form of stay 45 which previously restrained the motion of the float arm 57, is released. The cistern 1 then immediately begins to fill since the float arm 57 allows the inlet valve 50 to permit water to enter the cistern 1.

At the conclusion of the flushing action, the float stem 38 and flush valve 3 fall thereby closing off the cistern 1 and allowing the water level within the cistern to rise. This moves the float arm 57 in the clockwise direction as seen in Fig. 9 and again re-engages the lip 44 and notch 46. This again latches the stay 45 and returns the mechanism to the position illustrated in Fig. 2.

In view of the foregoing it will be seen that even if the flush valve 3 should leak, the maximum amount of water wasted between successive flushes is only the volume of water contained within the cistern 1. Furthermore, on the first operation of the flush actuator button 10, no flush is produced. However, it is immediately apparent to the user that the cistern 1 is being refilled. A subsequent operation of a flush actuator button 10 produces the necessary flush, but the person using the cistern to flush the toilet is advised (by the changed operation from the normal immediate flush following depression of the flush actuator button 10) that the cistern is not operating in its usual manner and should therefore be serviced.

The foregoing describes only one embodiment of the present invention and modifications, obvious to those skilled in the art, can be made thereto within the scope of the appended claims.

Claims (3)

1. An interlock mechanism for a flush valve operated cistern (1) having a flush valve (3) in the base thereof which, when opened, drains water stored in said cistern to constitute a flush, said cistern further having an actuator mechanism (11) interconnecting a flush actuator (10) with said flush valve (3) to open the latter on operation of said actuator (10), and an inlet valve (50) having a refill actuator (56,57) operable in response to the level of water in said cistern to refill same to a predetermined level wherein said interlock mechanism comprising a latch means (43-47) interconnectable with said refill actuator (56,57) and said flush actuator (10) and operable to prevent re-filling of said cistern, said latch means being releasable by operation of said flush actuator and being re-settable by initial re-filling of said cistern after a flush and wherein said refill actuator includes a first float (56) linked to a float arm (57) which is coupled to said inlet valve (50) and which is adjacent said actuator mechanism (11), said latch means comprises a pivoted lever (45) being movable by operation of said actuator mechanism (11) to move an abutment (46) on said pivoted lever (45) out of engagement with a stop member (44) of the latch means (43-47), and biasing means comprising gravity acting on said pivoted lever (45) to return said abutment (46) into engagement with said stop member (44) following operation of said actuator mechanism (11), characterized in that said float arm (57) is pivotally connectable to said inlet valve, said pivoted lever (45) is to be pivotally connected to said float arm (57) and is to extend between said float arm (57) and said actuator mechanism (11) and said stop member (44) is to be stationarily fixed relative to the cistern (1), wherein said interlock mechanism further includes a latch securing mechanism comprising a second float (41) mounted for movement with a pivoted locking lever (42) the pivoted locking lever (42) being pivotable to bear against said pivoted lever (45) with decreasing water levels in said cistern to secure said abutment (46) and stop member (44) in mutual engagement if said water level drops prior to actuation of said actuator mechanism (11).
2. An interlock lever as claimed in claim 1 wherein said pivoted lever (45) depends from said float arm (57), and a rising water level in said cistern raises said lever (45) to align said abutment (44) and stop member (46).
3. A method of operating a flush valve operated cistern (1) comprising an interlock mechanism as specified in claim 1 or 2, the cistern having a flush valve (3) in the base thereof which, when opened, drains water in said cistern (1) to constitute a flush, said cistern (1) further having an actuator mechanism (11) interconnecting a flush actuator (10) with said flush valve (3) to open the latter on operation of said actuator (10), and an inlet valve (50) having a refill actuator (56,57) operable in response to the level of water in said cistern (1) to refill same to a predetermined level; said method comprising the steps of

   (1) providing a latch mechanism (43-47) which is interconnected with said refill actuator (56,57) and said flush actuator (10) and which is operable to prevent refilling of said cistern (1),

   (2) releasing the latch mechanism (43-47) following operation of the flush actuator (10),

   (3) re-setting the latch mechanism (43-47) following initial refilling of said cistern (1) after a flush,

   (4) sensing the level of water in said cistern (1), and

   (5) securing said latch mechanism (43-47) to prevent refilling of said cistern (1) if the sensed level of water in the cistern (1) is low, wherein the sensing of the level of water in said cistern (1) is determined by the position of a pivoted locking lever (42) having a float (41).