GB2416783A

GB2416783A - Automatic urinal flushing system

Info

Publication number: GB2416783A
Application number: GB0415801A
Authority: GB
Inventors: Peter Gregory
Original assignee: FLUID SENSORS Ltd
Current assignee: FLUID SENSORS Ltd
Priority date: 2003-07-19
Filing date: 2004-07-15
Publication date: 2006-02-08
Anticipated expiration: 2024-07-15
Also published as: GB0415801D0; GB0316932D0; GB2416783B

Abstract

A urinal flushing system comprises a temperature sensor (R2) mounted on the outlet of the urinal, valve means (V1) in the feed pipe to the urinal, and an analogue control circuit connected to the temperature sensor (R2), the control circuit include means for responding to a rapid increase in temperature sensed by the temperature sensor (R2) and for sending a signal to the valve means (V1) to effect opening thereof in response to said temperature increase.

Description

241 6783

URINALS

Field of the Invention

This invention relates to urinals.

It is desirous to reduce the usage of clean water or other cleansing agents when flushing urinals.

Background to the Invention

The most common existing methods of flushing urinals are: a) Timed flush.

In this method, a cistern is commonly employed which is allowed to fill slowly through a restricting valve. When it is full, it empties itself through the urinal(s), thus flushing iVthem. The cistern then slowly refills and the process is repeated.

This method is reliable but wasteful of water since the urinal is regularly flushed whether or not it is used.

ee. ace e 2.e e Additionally, should the urinal waste pipe become blocked, the flush water overflows the urinal.

b) Indirect proximity sensing.

In this method, an electronic sensor detects if a person is in the room where the urinal is sited. On detecting a person, a valve is opened for a period of time to admit water to the cistern described in method a). As in method a), the cistern flushes the urinal(s) when it is full.

This method saves more water than method a) but will ultimately cause the flush to occur if people are in the room but not using the urinal. The sensors are prone to unreliability, and like method a), should the urinal outlet pipe become blocked, the system may continue to flush the urinal causing it to overflow. The system requires the installation of a cistern.

c) Direct usage sensing.

In these methods, a valve and usage sensor are attached directly to the plumbing of the urinal. The sensor detects use of the urinal and admits water to the urinal for a set period of time.

These systems tend to be an integral part of a particular manufacturer's sanitary ware and will require the urinal to be replaced. Depending on the method of sensing, these systems may still flush even if a person merely passes close by. They usually flush within moments of usage and do not offer a saving in water consumption in areas of heavy usage. The sensing e : a:: :: A: 3.* . . . equipment is sometimes fitted facing users and as such needs to be rugged, vandal-resistant and visually pleasing; accordingly it may be an expensive solution.

It is an object of the present invention to provide a method of providing for the flushing of a urinal in a flexible and cost-effective manner.

Summarv of the Invention According to a first aspect of the present invention there is provided a method of controlling the flushing of a urinal, the method comprising:- mounting a temperature sensor on the outlet of the urinal, providing valve means in the feed pipe to the urinal, connecting the temperature sensor to an analogue control circuit that responds to a rapid increase in temperature sensed by the temperature sensor, and sending a signal to effect opening of the valve means.

According to a second aspect of the present invention there is provided a urinal flushing system comprising:- a temperature sensor mounted on the outlet of the urinal, valve means in the feed pipe to the urinal, and an analogue control circuit connected to the temperature sensor, the control circuit include means for responding to a rapid increase in temperature sensed by the temperature sensor and for sending a signal to the valve means to effect opening thereof in response to said temperature increase.

e 4 *e The control circuit preferably includes a timer that provides for a time delay between sensing of the temperature increase and opening of the valve means.

The temperature sensor, which is attached to the waste trap at the outlet of the urinal, is preferably connected by two low- voltage wires to a valve/control unit that is fitted to the flush feed pipe. Conventional cisterns are not required; however if cisterns are part of an existing installation the system described above can still be fitted.

As will be understood by those knowledgeable in the art, the rate of rise of temperature of the liquid in the waste trap when the urinal is used will be greater than that which might occur due to ambient drift. Using standard known measurement techniques, a simple analogue circuit is preferably employed which only gives an output signal if the temperature rises quickly. The time constants of the analogue circuit are optimised for this particular purpose.

When this sharp increase of temperature occurs, a timer is started. The time delay would typically be a few minutes. Further use of the urinal after the initial use has no effect on the control circuit or the timer.

When the timer runs out, the valve is opened for a pre- determined period to admit water to the urinal to flush it. e e e te

ee e e e e e ce e eae e Once the flush has terminated, the control circuit is reset ready for the next usage.

The invention thus provides a urinal flush control system that can be fitted to both existing and new installations and to almost any type of urinal so as to provide significant benefits over existing systems.

It can be seen from the above that, in periods of frequent usage, the urinal will not flush more often that the time setting of the timer, so that a water saving is effected. It will further be observed that, if the urinal is not used, it will not be flushed at all.

It is to be noted that, should the outlet from the urinal become blocked, the warmer urine will not be able to enter the trap and will thus not be detected. Accordingly, flushing of the urinal will not be effected and the risk of flooding will be reduced.

In one embodiment of the invention, the temperature sensor is a low-cost device attached to the outside of the waste trap. This is connected to the control unit by two low-voltage wires. The control unit comprises a very low cost analogue circuit and a valve attached directly to the flush feed pipe. The control unit is powered from an external source such as the mains electrical supply. Thus, the complete system offers the benefits of low cost of both parts and installation, and can be fitted to both new and existing installations.

. :e. ..e:.: . ..

6... . . The valve and control unit may be sited some distance from the urinal e.g. above false ceilings or behind wall panels, which will give a modern, clean, aesthetic improvement over traditional cisterns.

The fact that the controls and pipework can all be readily concealed may be seen as an advantage in locations where vandalism might be a problem.

It will be observed that, since the circuit is sensing temperature, a simple enhancement may be made which would give an electrical output in the event of the temperature becoming low enough that there might be a risk of freezing. This output could be used to give a warning of a risk of freezing or to turn on a heater.

Brief Description of the Drawings

Figure 1 is a schematic view of a urinal fitted with a system in accordance with the present invention, and Figure 2 is a circuit diagram of the system.

Description of the Preferred Embodiment

As shown in Figure 1, a temperature sensor is mounted on the waste pipe of the urinal. The temperature sensor R2 is a thermistor whose resistance decreases with increasing temperature.

7:e a.: . ;: :e.e Normally the voltage at pin 2 of the operational amplifier U1: A is higher than the voltage on pin 3 of said operational amplifier by a fraction of a volt, that being the volt-drop across diode D1.

This results in the output pin 1 of U1: A being at a low voltage. As the ambient temperature may change slowly, the resistance of R2 will change slowly and alter the voltage on pin 2 of U1:A. The capacitor C1 is caused to charge and discharge slowly such that the voltage difference between pins 2 and 3 of U1: A remains largely unaltered. In this condition the output of U1: A, pin 1, stays at a low potential.

With the output of U1:A at a low potential, the voltage on input pin 6 of U1:B is lower than that on input pin 5, so the output pin 7 of U1:B is at a high potential, which holds capacitor C2 in a charged condition through RV1 and D4. This, in turn, results in input pin 9 of U1:C being at a higher voltage than input pin 10 of U1:C, so the output pin 8 of U1:C is at a low voltage, transistor TR1 is not switched and neither is the relay RL1 or the valve V1.

When the urinal is used, the resistance of R2 changes downwards more quickly such that the voltage on pin 2 of U1:A drops quite quickly. The voltage in pin 3 of U1:A is not able to drop so quickly due to the need to discharge C1, and accordingly the voltage difference between pins 2 and 3 of U1:A is inverted and the output of U 1:A changes state.

When the output of U1:A goes high, input pin 6 of U1:B is put at a higher voltage than input pin 5 of U1:B, which causes the A. .:. . e:: ::e 8.... it. ::.

output of U1:B to go low. This pulls input 5 of U1:B lower through resistor R7 and diode D2 such that, even if the output of U1:A subsequently reverts to its original low level, input pin 5 of U1:B stays lower than input pin 6 and the output of U1:B remains at a low potential.

Since C2 is no longer receiving bias current from the output of U1:B, it starts to discharge through resistor RV2 and diode D3.

The value of this resistor sets the rate at which C2 is discharged and so determines the time delay between the first use of the urinal and eventual flushing thereof. It will be observed that since the output of U1:B has become latched low as described above, further use of the urinal and further changes of state of the output of U1:A will make no difference at this stage.

Once the potential of C2 has fallen to the point at which input pin 9 of U1:C has a lower voltage than input pin 10, the output pin 8 of U1:C changes state to a high level, which turns on TR1, which in turn energises relay RL1 which supplies power to the valve which opens and admits water to the urinal to flush it.

The action of the U3:C output going high causes the voltage on pin 10 of U1:C to be taken to a significantly higher voltage increasing the margin between pin 9 and 10 of U1:C and ensuring that there is no 'jitter' of the output of U1:C.

Meanwhile, the action of the U1:C output going high causes bias current to be fed to the resistor network on input pin 5 of U1:B, which is sufficient for its potential to become higher than that A. e:e :: : : .e :e:.

on pin 6 and, as a consequence, the output of U1:B reverts to its original high state. This causes capacitor C2 to be charged through D4 and RV1, the value of the latter determines the time taken for C2 to charge up and hence the period for which the valve V1 is open.

Since the voltage on pin 10 of U1:C is now at a higher voltage as described above, the capacitor C2 has to be charged to almost its fully charged condition before the voltage on pin 9 of U1:C is higher than that on pin 10, and the output of U1:C reverts to its low level and the transistor TR1, relay RL1 and valve V1 are all turned off stopping the flushing.

The circuit is now reset to its original state ready for the next usage.

The invention thus provides a system that results in a urinal that only flushes when it has been used, yet doesn't flush excessively frequently in the event of frequent use. Equally, there is a reduction in the volume of waste water that has to be disposed of.

The system can readily be fitted to most urinals at the time the urinal is installed and can also be fitted to a urinal that is already in place.

It is possible for a warning to be given of low temperature conditions. For example, a signal may be generated to warn of a risk of freezing or to activate a heater to prevent freezing.

ëeve . e . . . . . ...

10.... . . . By the nature of operation of the system, the urinal will not be flushed if its outlet port becomes blocked, thereby reducing the likelihood of flooding.

Claims

11 a. Claims: 1. A method of controlling the flushing of a urinal, the

method comprising:- mounting a temperature sensor on the outlet of the urinal, providing valve means in the feed pipe to the urinal, connecting the temperature sensor to an analogue control circuit that responds to a rapid increase in temperature sensed by the temperature sensor, and sending a signal to effect opening of the valve means.

2. A method of controlling the flushing of a urinal substantially as hereinbefore described with reference to the accompanying drawings.

3. A urinal flushing system comprising:- a temperature sensor mounted on the outlet of the urinal, valve means in the feed pipe to the urinal, and an analogue control circuit connected to the temperature sensor, the control circuit include means for responding to a rapid increase in temperature sensed by the temperature sensor and for sending a signal to the valve means to effect opening thereof in response to said temperature increase.

4. A urinal flushing system as claimed in Claim 3, in which the control circuit includes a timer that provides for a time delay between sensing of the temperature increase and opening of the valve means.

: :. . ;: a: .: it:

5. A urinal flushing system as claimed in Claim 3 or Claim 4, in which the temperature sensor is connected by two low-voltage wires to a valve/control unit that is fitted to the feed pipe.

6. A urinal flushing system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.