| 摘要 |
Malfunction or failure of mechanical, electrical, and electro-mechanical equipment, for example, equipment used in manufacturing operations, is often preceded by an increase in the operating temperature of at least some portion of the equipment. A temperature-sensitive, active material-containing actuator is pre-selected to operate at a pre-determined temperature indicative of impending equipment failure and placed in thermal contact with the equipment. If the equipment achieves the pre-selected temperature the actuator signals this by closing an externally-powered circuit to enable or provide a suitable alarm signal. Additionally, the actuator may close a second circuit connected to a machine controller to alert the machine controller to take some pre-programmed action. Selected actuators are based on shape memory alloys (SMA) adapted to operate over a temperature range sufficient to encompass the expected range of pre-determined temperatures. |
| 主权项 |
1. A device for placement in thermal communication with a machine or machine component, the device serving to detect and give notice of an over-heating condition in the machine when the machine or machine component is operating or has been operating; the device comprising:
a base with a surface for surface-to-surface contact with a surface of the machine or machine component and an opposing mounting surface, the base being thermally conductive so that heat generated by the machine or machine component may be communicated through the base; a shaped body of an active material secured to the base mounting surface, the shaped active material body being composed to experience a shape and stiffness change when it is heated from a reference temperature indicative of a normal machine operating temperature, to a predetermined temperature, higher than the reference temperature, the predetermined temperature being selected to be indicative of an over-heating condition in a machine, the shaped body of active material being heated by heat from the machine to raise the temperature of the active material body to a temperature indicative of a machine operating temperature; a resettable, alarm-giving circuit comprising a switch secured to the base mounting surface, the switch reversibly adopting two states upon operation, a closed state which enables passage of electricity through the switch, and an open state which denies passage of electricity through the switch; the switch being either a normally-open switch which, in its initial state, denies passage of electricity through the switch until the switch is operated to render the switch in its alternate state, or a normally-closed switch which, in its initial state, enables passage of electricity through the switch until the switch is operated to render it in its alternate state; and the active material being arranged so that it engages the switch and so that the shape and stiffness change experienced by the active material when it is heated to the predetermined temperature, operates the switch to transition the switch to its alternate state, the change in state of the switch serving to signal a machine over-heating condition and to operate the alarm-giving circuit. |
