1. Field of the Invention
The present invention relates to a motion guide apparatus, such as a linear motion guide apparatus or a ball screw device, and more particularly to a motion guide apparatus including two movable members or a screw shaft and a ball nut movable relative to each other, and a temperature detecting device attached to one of the two movable members for detecting the temperature of the motion guide apparatus and for preventing the motion guide apparatus from overheating.
2. Description of the Prior Art
Typical working machines, such as rolling mills comprise a roll bearing engaged in a work roll of a roll stand for directly measuring the temperature at the bearing without detaching connecting lines during changing of rolls.
For example, U.S. Pat. No. 4,939,920 to Stahl discloses one of the typical monitoring devices for roll bearings in rolling mills and comprising a monitoring device installed in the chock of the work roll of a roll stand, and resided in a cartridge or in a thermal limit value pickup in contact with the roll bearing.
However, the cartridge may have a good chance to be broken or damaged after use, but may not be easily and quickly changed or replaced with the other new ones because the cartridge is deeply received or engaged in the monitoring device and may not be easily disengaged from the thermal limit value pickup or device and thus may not be easily repaired.
Typical motion guide apparatuses, such as the linear motion guide apparatuses or the ball screw devices comprise two movable members rotatable or movable relative to each other, and a number of ball bearing elements disposed between the two movable members for facilitating the sliding movement between the two movable members and may generate a great heat when the two movable members are rotated relative to each other in a great rotational speed.
However, no temperature detecting devices have been developed and provided and attached to one of the two movable members for detecting the temperature of the motion guide apparatus, and a great heat may be generated between the movable members and the ball bearing elements, such that the users may not aware the temperature of the movable members and may not prevent the motion guide apparatus from overheating.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional motion guide apparatuses.
The primary objective of the present invention is to provide a motion guide apparatus including two movable members movable relative to each other, and a temperature detecting device attached to one of the two movable members for detecting the temperature of the motion guide apparatus and for preventing the motion guide apparatus from overheating.
In accordance with one aspect of the invention, there is provided a motion guide apparatus comprising an elongated shaft including a helical groove formed on an outer peripheral surface thereof, a ball nut movably attached onto the elongated shaft, and including a bore formed therein for receiving the elongated shaft, and including a helical groove formed therein, and including a compartment formed therein, a deflecting device engaged with the ball nut and communicative with the helical groove of the ball nut for forming an endless ball guiding passage between the ball nut and the elongated shaft, a number of ball bearing elements received and engaged with the endless ball guiding passage and engaged between the elongated shaft and the ball nut, and a temperature detecting device engaged into the compartment of the ball nut for detecting a temperature of the ball nut and for preventing the ball nut from overheating.
The temperature detecting device includes an indicating device coupled to the temperature detecting device for generating an indicating signal when the temperature detecting device has sensed that the temperature of the ball nut and/or the screw shaft is higher than the predetermined temperature or value, and the user may then stop working to find out what problems have been happened and thus to prevent the motion guide apparatus from overheating.
The temperature detecting device includes a power source electrically coupled to the temperature detecting device and the indicating device for energizing the temperature detecting device and the indicating device.
The temperature detecting device includes a resistor electrically coupled in parallel to the indicating device for preventing the indicating device from being loaded and for preventing the indicating device from being damaged and for increasing the working life of the indicating device.
The temperature detecting device includes a heat conductive member disposed between the ball nut and the temperature detecting device for transmitting or conducting the heat from the ball nut to the temperature detecting device or between the ball nut and the temperature detecting device and for facilitating the temperature detecting effect or function of the temperature detecting device.
Further objectives and advantages of the present invention will become apparent from a careful reading of the detailed description provided hereinbelow, with appropriate reference to the accompanying drawings.
Referring to the drawings, and initially to
The ball nut 20 includes a returning channel (not shown) longitudinally or axially formed in the outer peripheral portion thereof, and intersecting or communicating with helical threaded portions or grooves 22 or the ball guiding passage 8, and includes two depressions 23 formed therein (
The ball nut 20 further includes a recess or space or compartment 25 formed therein and arranged or located close to, but not communicative with the helical threaded portions or grooves 22 or the ball guiding passage 8, and a temperature detecting device 30 is attached to one of the two movable members 20, such as engaged into the compartment 25 of the ball nut 20, and may be contacted with the ball nut 20 or non-contacted or spaced from the ball nut 20, and may be selected from a thermo-couple, or a thermistor for detecting the temperature of the ball nut 20 and/or the screw shaft 10 of the motion guide apparatus 1 and for preventing the motion guide apparatus 1 from overheating. For example, when the temperature detecting device 30 has sensed or detected that the temperature of the ball nut 20 and/or the screw shaft 10 is higher than a predetermined temperature or value, the user may stop working to find out what problems have been happened and thus to prevent the motion guide apparatus 1 from overheating.
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Accordingly, the motion guide apparatus in accordance with the present invention includes two movable members movable relative to each other, and a temperature detecting device attached to one of the two movable members for detecting the temperature of the motion guide apparatus and for preventing the motion guide apparatus from overheating.
Although this invention has been described with a certain degree of particularity, it is to be understood that the present disclosure has been made by way of example only and that numerous changes in the detailed construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.