Abstract:
Temperature monitoring device for monitoring or controlling the temperature of an object, and preferably indicating and/or recording abnormal temperature variations of the object includes a housing having a contact portion for contacting the object, a sensing member in heat transferring contact with the contact portion for emitting signals representative of the object temperature, a control device that receives signals from the sensing member and actuates an indicator, a power source connectable to the sensing member, the control device and the indicator, and a switch biased to interrupt the power supply to the sensing member, control device and indicator. A portion of the housing is movable between a first position where the switch interrupts the power supply and a second position in which the housing portion urges the switch to the power supply position.

Description:
This application is based on and claims priority under 35 U.S.C. § 119 with respect to Swedish Application No. 0001625-3 filed on May 3, 2000, the entire content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a temperature monitoring device. More specifically, the present invention pertains to a temperature monitoring device for controlling the temperature of an object, and for possibly also indicating and/or recording abnormal temperature variations. Although not limited in this regard, the device of the present invention can be to observe the temperature conditions of a bearing in operation. 
     BACKGROUND OF THE INVENTION 
     In modern bearing technology, bearings operate best within certain temperature ranges. For different types of bearings and/or different types of bearing applications, this temperature range can vary. During operation, the temperature will vary based on variations in different parameters such as load, speed and amount of lubricant. A rise in the bearing temperature above a certain level can thus provide an indication that there are risks that the bearing assembly may be starting to break down, thus presenting the possibly of causing damage to the machine equipment and/or other components with which the bearing assembly is associated. 
     Different temperature monitoring devices have been developed over the years, which are often rather complex and expensive, which might incorporate for instance a bimetallic relay, and which following a temperature increase exceeding a certain numeric value, open a valve to permit injection of a small amount of lubricant in the bearing. There are also relatively simple mechanical temperature monitoring devices which, for example, use a spring element having a shape memory effect to visually indicate that the temperature has passed a certain critical temperature level. A significant problem associated with such earlier known temperature monitoring devices, such as those disclosed in U.S. Pat. No. 4,448,147, is that they must be carefully calibrated before use. Also, these devices usually also have an ability to react only when a certain numerical temperature value has been exceeded, but are not sensitive to temperature variations over large ranges insofar as such ranges do not overlap the specified temperature value. 
     A need thus exists for a temperature monitoring device which is relatively simple in design and relatively easy to install, while at the same time bing quite efficient. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a temperature monitoring device for continuously monitoring the temperature of an object includes a housing having contact means engageable with the object for producing heat transferring contact with the object, indicating means for outputting an indication of a temperature condition of the object, a sensing member positioned in heat transferring contact with the contact means to emit a signal representative of a current temperature of the object, and a control device connected to the sensing member to receive the signal from the sensing member representative of the current temperature of the object and to emit a signal to the indicating means to output the indication of the temperature condition of the object. A power supply means supplies power to the control device, the sensing member and the indicating means, and a switch means is urged to a first condition interrupting the supply of power from the power supply means to the control device, the sensing member and the indicating means, and is movable into a second condition causing the power supply means to supply power to the control device, the sensing member and the indicating means. A portion of the housing is movable between a first position in which the switch means is urged to the first condition and a second position in which the portion of the housing contacts the switch means to cause the power supply means to supply power to the control device, the sensing member and the indicating means. 
     According to another aspect of the invention, a temperature monitoring device for continuously monitoring the temperature of an object includes a housing adapted to be connected to the object, a sensing member sensing a current temperature of the object by way of heat transfer when the housing is connected to the object and emitting a signal representative of the current temperature of the object, an indicator mounted on the housing for outputting an indication of a temperature condition of the object, a processor connected to the sensing member to receive the signal from the sensing member representative of the current temperature of the object and to emit a signal to the indicating means to output the indication of the temperature condition of the object, and a power supply that supplies power to the processor, the sensing member and the indicator. A switch is changeable between a first condition in which power from the power supply to the processor, the sensing member and the indicating means is interrupted, and a second condition in which power is supplied from the power supply to the processor, the sensing member and the indicating means. A mechanism is provided for changing the switch between the first condition and the second condition. 
     In accordance with a further aspect of the invention, a temperature monitoring device for continuously monitoring the temperature of an object includes a housing adapted to be removably connected to the object and having a contact portion to contact the object in a heat transfer manner, a sensing member mounted on the housing in heat transferring contact with the contact portion of the housing to sense a current temperature of the object by way of heat transfer when the housing is connected to the object and emitting a signal representative of the current temperature of the object, an indicator mounted on the housing which produces an output indicating a temperature condition of the object, and a processor connected to the sensing member and the indicating means to receive the signal from the sensing member representative of the current temperature of the object and to emit a signal to the indicating means causing the indicating means to produce at least a first output indicating the temperature condition of the object. The processor determines a normal operating condition temperature of the object when a steady-state temperature of the object sensed by the sensing member has been reached and determines an abnormal operating condition temperature of the object when the temperature of the object sensed by the sensing member is outside a predetermined range from the normal operating condition temperature. The processor emits a signal to the indicator upon determining the abnormal operating condition temperature of the object so that the indicator produces the first output indicating the abnormal operating condition temperature of the object. In addition, a power supply supplies power to the processor, the sensing member and the indicator. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURE 
     The foregoing and additional features and characteristics of the present invention will become more apparent from the following detailed description considered with reference to the accompanying FIG. 1 which is an exploded perspective view of the temperature monitoring device of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The temperature monitoring device of the present invention as shown in FIG. 1 includes an elongated rod-like housing  1 . A fitting  2  is adapted to be connected to one axial end of the housing. The fitting  2 , which forms a contact portion of the housing, includes a threaded portion  3  for attachment of the fitting and the overall device to a threaded bore in the object that is to be supervised or monitored. The opposite axial end of the housing  1  carries a cover  4 . This cover  4  is provided with at least one transparent portion. The transparent portion can be in the form of one or more transparent windows provided in the cover or can be in the form of the cover itself being made of transparent material. 
     As can be seen from FIG. 1, the housing  1  is in the form of a substantially cylindrically-shaped tube. The axial end of the housing that is opposite the end carrying the fitting  2  is provided with a socket or open end  5 . The housing includes a cover  4  that is adapted to be received in the socket or open end  5  of the housing. The inner surface of the housing is provided with two diametrically opposed longitudinal grooves  6  extending through the interior of the housing. A removable frame  7  is adapted to be inserted into the interior of the housing, with the side edges of the frame  7  guided in the grooves  6  in the housing. 
     The frame  7  supports a power supply  8 , an indicator  9 ,  10 , a control device  11 , a switch member  12  and a sensor member  13 . In the illustrated embodiment of the invention, the power supply  8  is the form of a battery, the indicators  9 ,  10  are constituted by light emitting diodes (e.g., two differently colored light emitting diodes, such as one green and one red), the control device  11  is in the form of a processor, and the sensor member  13  is constituted by a thermistor. The thermistor  13  is formed as a limb or arm projecting from the frame  7 . The thermistor  13  and the switch member  12  are thus rigidly interconnected by virtue of being mounted on a common frame along with the battery  8 , the light emitting diodes  9 ,  10 , and the processor  11 . The power supply or battery  8  can be connected, by way of the switch member  12 , to the thermistor  13 , the processor  11  and the light emitting diodes  9 ,  10  via conduits printed on the frame. 
     When the frame  7  is fully inserted into the housing  1 , the light emitting diodes  9 ,  10  are positioned just inside the cover  4  so that they can be seen from outside the housing through the transparent portion of the cover  4  (i.e., through the transparent window(s) or through the cover itself when the cover is made of transparent material). With the frame  7  positioned in the interior of the housing, the battery  8 , the processor  11 , the switch member  12  and the thermistor  13  will be situated inside the housing  1  to thereby be protected and enclosed by the surrounding housing. 
     The fitting  2  has a bar-shaped portion  14  extending axially in a direction away from the threaded portion  3  of the fitting. This bar-shaped portion  14  has a non-round shape to define a generally flat surface portion, and is arranged to be received in a correspondingly shaped non-round cavity in the end of the housing  1 . 
     The interior of the housing  1  is further provided with two diametrically opposed and circumferentially extending short grooves  15  (only one of which is visible in the drawing FIGURE). The grooves  15  thus extend over only a short inner circumferential portion of the housing interior. In the illustrated embodiment, the two grooves are positioned at locations displaced about 90′ in relation to the internal grooves  6  in the housing. 
     When the device thus described is mounted, the frame  7 , including the battery  8 , the light emitting diodes  9 ,  10 , the processor  11  and the switch member  12 , is pushed into the housing  1 , with the edges of the frame  7  being received in and guided by the internal longitudinally extending grooves  6  of the housing. As mentioned above, with the frame  7  mounted in the housing, the light emitting diodes  9 ,  10  are located inside the transparent portion of the cover  4 . When the frame  7  is in its completely inserted position in the housing  1 , the thermistor  13  is in heat transferring engagement or contact with the bar shaped or flat surface portion  14  of the fitting  2 . 
     The side of the cover  4  facing the housing  1  is provided with axially extending shoulders  16 , only one of which is visible in the drawing. These shoulders are arranged to be guided in the grooves  15  in the interior of the housing so that the cover  4 , when in position, can be rotated a short distance. The cover  4  also has an axially extending internal knob  17 . This knob  17  is positioned so that at one rotational position of the cover  4  the knob  17  presses the switch  12  on the frame to thereby connect the thermistor  13 , the processor  11  and the light emitting diodes  9 ,  10  with the power supply (i.e., battery)  8  for energizing these current consuming elements, whereas in the other rotational position of the cover  4  the knob  17  is out of contact with the switch  12 . The switch  12  is thus biased or positioned at a first condition to interrupt the supply of power from the power source to the current consuming elements (the processor, the thermistor and the light emitting diodes) and is movable to a second condition through engagement of the switch  12  with a portion of the housing (i.e., the knob  17  on the cover  4 ) to balance the biasing effect and cause power to be supplied from the power supply to the current consuming elements. The knob  17  and cover  4  thus form a mechanism for changing the switch member  12  between the first condition and the second condition. The rotational movement of the cover required for turning on and turning off the device can be, for example, 90 degrees or less. An O-ring seal  18  is positioned between the housing I and the cover  4  for protecting the interior of the housing from moisture and dirt. 
     After being turned on, the battery  8  will continue to deliver drive current to the current consuming elements for as long as the switch is kept in this position or condition. However, the switch  12  is biased by a spring load or the like towards the closed position or closed condition, and will therefore switch off the current supply to the current consuming elements if the cover  4  is turned in the opposite direction so that the knob  17  on the cover  4  is moved away from the switch  12 . It is thus possible to switch on and switch off the device by simply rotating the cover  4 . 
     The function and operation of the device of the present invention is as follows. In use, the fitting  2  of the device is fitted or connected to an object whose temperature is to be monitored, e.g., bearing housing. This can be accomplished by screwing the threaded portion  3  of the fitting  2  into a threaded bore in the object so that the fitting is in heat conducting or heat transferring contact with the object. The drawing FIGURE illustrates an object  20  having a threaded bore  21  for receiving the threaded portion  3  of the fitting  2 . 
     When the monitoring work or operation is to begin, the cover  4  is turned by an appropriate amount in the appropriate direction (for example 90° in the clockwise direction) so that the cover  4 , at the end of this rotation, will be positioned such that the knob  17  presses on the switch  12 . The current consuming elements will thus be energized or supplied with power from the battery or other appropriate power source  8 . 
     The current supplied from the battery  8  causes the thermistor  13  to begin metering or monitoring the temperature of the bar shaped portion  14 . The processor causes one or both of the light emitting diodes  9 ,  10  to flash, thereby indicating that the device is active. This can for instance be shown as two short flashes of a green light emitting diode followed by one short flash of a red light emitting diode. 
     The thermistor then begins to meter or monitor the temperature, and this can be shown by an appropriate signal from one or more of the light emitting diodes, for example the green light flashing, e.g. once every 60 seconds. 
     The temperature in the object is sensed over an extended period of time, e.g., two hours, when the object is supposed to have reached its steady-state temperature or normal operating temperature, whereupon the processor records or stores such temperature of the object. The processor then causes an appropriate signal to be emitted from one or more of the light emitting diodes. This can involve the green light emitting diode beginning flashing, e.g. once every 30 seconds. This is the normal operating condition for the device, and this condition is maintained as long as the temperature of the object remains within a specified range from the temperature recorded or stored as the normal condition temperature. 
     If however the temperature should rise above a predetermined lever, for example 10° C. above this normal condition temperature, the processor causes an appropriate signal to be issued from one or more of the light emitting diodes to thus indicate an abnormal temperature condition or error condition. This can involve, for example, the red light emitting diode starting to flash, e.g., three times for every 30 seconds. The operator is thus appropriately informed of the existence of an error condition or abnormal temperature condition with the object. 
     The operator then controls the cause of the error condition and takes the necessary steps for removing the error. When this is done successfully and the temperature again drops to the normal condition, the red light emitting diode is turned off and the green light emitting diode resumes its flashing condition, for example once every 30 seconds, thereby indicating a normal temperature condition for the object being monitored. 
     If the normal operating temperature for the object increases for some reason, e.g., through an exchange or replacement of components incorporated in the object, such as bearings or the like, the cover  4  is rotated in the direction opposite to the direction in which the cover was rotated to render the device operational (e.g., counter-clockwise). The knob  17  of the cover  4  will thus move away from the switch  12  to interrupt the power supply from the battery  8  to the current consuming elements, thus causing the temperature monitoring device to become inactive. 
     After a rest period, e.g. 30 minutes, the cover  4  is again turned in the appropriate direction (e.g., clockwise) to initiate the operational state of the device, whereupon the same procedure as that described above is resumed. However, after the first “normalizing” time period of, for example, two hours, the device starts to function in the normal state, but at a higher basic temperature. 
     It is thus possible to use the same or exactly similar devices in accordance with the invention for objects where changing normal temperature conditions occur, and also for applications having rather different basic normal temperature ranges, as the device of the present invention does not control or indicate if the object being monitored exceeds a certain numerical temperature value, but instead controls or monitors if the object undergoes a temperature increase from an arbitrary temperature level exceeding a certain temperature range, e.g., 10° C. 
     The fitting  2  with its threaded portion  3  and its rod shaped or flat surface portion  14  are preferably made from brass or another appropriate material having good temperature conducting properties. The frame  7  and the housing  1  can be manufactured from any suitable material that is sufficiently robust to withstand rough handling during use. These materials include plastic materials, such as polycarbonate. 
     The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiment disclosed. Further, the embodiment described herein is to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.