GB2201537A

GB2201537A - Temperature indicating system

Info

Publication number: GB2201537A
Application number: GB08704408A
Authority: GB
Inventors: Leslie Richard Morton; Bernard Harold Barber
Original assignee: Davy McKee AG
Current assignee: Davy McKee AG
Priority date: 1987-02-25
Filing date: 1987-02-25
Publication date: 1988-09-01
Also published as: GB8704408D0

Abstract

To indicate when the temperature of an inaccessible body is at a predetermined level, a transmitter assembly 1 is mounted with a temperature sensor in thermal contact with the body and a signal is transmitted when the predetermined level is reached. A receiver 2 remote from the body receives the signal and produces an output which is used to sound an alarm or to prevent further heating of the body. The transmitter may transmit radio, light, infra-red or sound waves. <IMAGE>

Description

TEMPERATURE INDICATING SYSTEM There are many industrial applications where it is essential that, in use, the temperature of a body does not exceed a predetermined level. As an example, gear boxes, drive spindles and bearings for rotatable members often tend to overheat when in use due to a number of causes, such as lack of lubrication or reduced running clearances. It is important that excessive temperature rises be indicated and action taken to reduce the temperature level before serious damage and expensive stoppages result.

Clearly, in many applications it is possible to apply a temperature indicator to the body concerned.

In certain applications, however, such as a gear box, the body may be in an inaccessible position within a casing which renders it extremely difficult to obtain an indication of the operating temperature of the body by conventional means.

An object of the present invention is to provide a system for indicating when the temperature of a body is at a predetermined level.

According to the present invention, a system for indicating when the temperature of a body is at a predetermined level comprises a transmitter assembly adapted to be mounted in thermal contact with the body, the assembly including an electric power source, a temperature sensor and a transmitter which is caused to transmit a signal when the sensor senses that the body temperature is at said predetermined level; and a receiver assembly positioned remote from the transmitter and which is arranged to provide an output when said signal is received.

If, during use, the temperature of the body rises to said predetermined level, the transmitter transmits a signal and the receiver assembly, on receiving the signal, produces an output which can be used to operate some form of alarm or to control the body to reduce its temperature to a more acceptable level.

The signal transmitted by the transmitter may take a number of forms, it may be light or infra-red radiation, a sound signal, a laser beam or a radio frequency signal. The receiver is arranged to receive the chosen form of signal and to be able to act accordingly and produce an output when the signal is received.

Since the transmitter assembly is selfcontained with its own electric power source, the assembly can readily be located in contact with the body, the temperature of which is to be monitored. For example, when the body is a gear wheel inside a gear box, a bore can be formed in the gear wheel and the transmitter assembly located in the bore. The receiver assembly is then located on a wall of the gear box where it can receive the signal transmitted by the transmitter.

In order that the invention may be more readily understood, it will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a block diagram showing the essential features of the system of the present invention; Figure 2 is a diagrammatic view of part of a gear box; Figure 3 is a diagrammatic view of a coupling between a pair of rotatable shafts; Figure 4 is a diagrammatic view of a shaft mounted coupling; and Figure 5 is a diagrammatic view of a bearing assembly for a rotatable shaft.

Referring to Figure 1, a system for indicating when the temperature of a body is at a predetermined level comprises a transmitter assembly 1 and a receiver assembly 2. The transmitter assembly is a self-contained unit which is positioned in or on the body, the temperature of which is to be monitored. The assembly comprises a temperature sensor 3 which is in thermal contact with the body which may take the form of a bi-metal strip switch. Alternatively it could be an SME detector which changes its resistance significantly at a predetermined temperature. At the predetermined temperature the sensor 3 operates and the transmitter 4 is actuated electrically from its own power source 5, conveniently in the form of a nickel cadmium or lithium base battery. The transmitter may be an infra-red transmitter which, when it is actuated, emits a beam of radiation at infra-red frequency.

The receiver assembly 2 is positioned remote from the transmitter assembly and consists of a receiver 6 in direct line of sight of the transmitter and capable of receiving the type of signal emitted by the transmitter 4. When the receiver receives a signal from the transmitter 4, it produces an output which may be used to actuate some form of alarm system 7 or it may be supplied to a fault monitoring system 8 which takes the necessary action to cause the temperature of the body to be reduced to a more acceptable level.

In Figure 2 a pair of meshing gears 10, 11 are mounted in a gear box 12. It is essential that the operating temperature of the gear 11 does not exceed a predetermined level and, to this end, a transmitter assembly 1 is located in a bore 13 formed in the gear 11. The temperature sensor of the assembly is in good thermal relation with the gear and, when the temperature of the gear is below the predetermined level, there is no output from the transmitter assembly and, consequently, its power source is not being drained. In the event, however, that the temperature of the gear wheel 11 does exceed the predetermined level, the sensor actuates the transmitter and a signal is transmitted.This signal will be detected by a receiver assembly 2 mounted in spaced relation with respect to the gear in an opening in the wall 12 of the gear box and in line of sight at least once for each revolution of the gear. Upon receiving the signal, the receiver actuates the alarm device or the fault monitoring equipment and action can be taken to reduce the temperature of the gear 11 such as by increasing the level of lubrication or, in extreme cases, by shutting down the gear box.

In the arrangement shown in Figure 3, the transmitter 1 is located in a bore in one part of a two-part coupling 13 and the receiver 2 is positioned where it can receive the signal from the transmitter but in a readily accessible position remote therefrom.

Similarly, in Figure 4, a transmitter 1 is mounted in a shaft coupling 14 and the receiver is arranged to receive the output signal from the transmitter but it is spaced therefrom.

In Figure 5 the invention is shown applied to a bearing 15 for supporting a rotating shaft. The transmitter assembly is mounted on the bearing 15 to sense the temperature thereof and the receiver assembly 2 is positioned where the signal from the transmitter 1 can be received but which is in a more accessible position than the bearing 15.

Claims

Claims:

1. A system for indicating when the temperature of a body is at a predetermined level, said system comprising a transmitter assembly including a power source, a temperature sensor mounted in thermal contact with the body and a transmitter which is caused to transmit a signal when the sensor senses that the body temperature is at said predetermined level; and a receiver assembly positioned remote from the transmitter assembly; said receiver assembly being capable of receiving said signal and arranged to produce an output when said signal is received.

2. A system as claimed in claim 1, in which the transmitter and the receiver are in line-of-sight relationship to enable said signal transmitted by the transmitter to be received by the receiver.

3. A system as claimed in claim 2, in which the signal is in the form of visible light or infra-red radiation.

4. A system as claimed in claim 1, in which the transmitter and the receiver are not in line-of-sight relationship and the signal is a radio frequency signal.

5. A system as claimed in any preceding claim, in which the power source is a battery.

6. A system as claimed in any preceding claim, in which the receiver assembly includes an alarm which produces an audible or a visible alarm signal when the receiver assembly produces an output.

7. A system as claimed in any preceding claim, in which said body is movable with respect to the receiver assembly.

8. For use in a system as claimed in any preceding claim, a transmitter assembly comprising a metal tube containing a power source, a transmitter and a temperature sensor, said sensor being in thermal contact with the wall of the metal tube.

9. A transmitter assembly as claimed in claim 8, in which the transmitter when actuated transmits a signal of visible light or infra-red radiation.

10. A system for indicating when the temperature of a body is at a predetermined level substantially as hereinbefore described with reference to the accompanying drawings.