Patent Application
20060125613
1. Field of the Invention
The present invention relates to apparatus to detect the air pressure of a vehicle wheel.
2. Description of the Related Art
The pressure of a vehicle wheel will leak gradually after a certain period in use, or when the temperature drops at night after radiation by sunlight. It is dangerous to drive the car if the tire pressure dropped below 28 psi. Insufficient tire pressure may cause the vehicle wheel to explore during a high speed running.
Various tire pressure detector and alarm devices have been disclosed and have appeared on the market. Exemplars are seen in Taiwan Publication Nos. 536489; 400811; 149143; 177543; 560445; 574077; 090946; 100539; 396794. These devices may use an electronic tire pressure detector or a mechanical tire pressure detector to detect the tire pressure. An electronic tire pressure detector uses a pressure sensor IC to detect tire pressure. However, an electronic tire pressure detector consumes much electric energy and is relatively less reliable.
A mechanical tire pressure detector must be installed in the rim or air valve of the vehicle wheel.
The aforesaid tire pressure detector and radio receiver system still has numerous drawbacks as outlined hereinafter:
1. The radio receiver 18 is arranged in a box. After mounting of the radio receiver in the motor vehicle, a power circuit must be installed to electrically connect the radio receiver to the battery power supply circuit of the motor vehicle. The installation of the radio receiver destroys the sense of beauty of the motor vehicle (see
2. Because the front neck 15 of the casing 10 is directly threaded onto the air valve 16, a thief can remove the tire pressure detector from the air valve easily without any tool. Further, the tire pressure detector may be loosened easily upon vibration of the motor vehicle.
3. When removed the tire pressure detector from the air valve for inflating the vehicle wheel or receiving a repair work, the metal spring member 12 immediately pushes the movable metal contact plate 11 upwards into contact with contacts 17 to close the circuit, thereby wasting much electric energy.
4. The movable metal contact plate 11 tends to be forced upwards into contact with contacts 17 accidentally during vibration of the motor vehicle, thereby producing a false alarm signal.
The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a tire pressure detector and alarm system, which has the receiver and alarm unit designed connectable to the socket for cigarette lighter to obtain the necessary working voltage from the car battery power supply. It is another object of the present invention to provide a tire pressure detector and alarm system, which positively locks the tire pressure detector to the air valve of the vehicle wheel, presenting disconnection of the tire pressure detector from the air valve by an external force. It is still another object of the present invention to provide a tire pressure detector and alarm system, which automatically cuts off the circuit to save power consumption when disconnected from the air valve of the vehicle wheel. It is still another object of the present invention to provide a tire pressure detector and alarm system, which is highly reliable and durable. To achieve these and other objects of the present invention, the tire pressure detector and alarm system comprises a battery-operated tire pressure detector installed in the air valve of a vehicle wheel and controlled by a control switch formed of a metal probe and a diaphragm held metal conductor member for providing a radio alarm signal when tire pressure low, a locking device installed in the air valve of the vehicle wheel to lock the tire pressure detector to the air valve, and a receiver and alarm unit directly connectable to the socket for cigarette lighter for receiving radio alarm signal from the tire pressure detector and display the signal.
Referring to
Referring to FIGS. 5˜7, the tire pressure detector 20 comprises:
a first metal casing 21, which comprises a front neck 211 connectable to the air valve 40, a first outer thread 212 extending around the periphery of the front neck 211, a second outer thread 213 extending around of the periphery of the body thereof, a first O-ring 214 mounted inside the front neck 211, and a second O-ring 216 fastened to the second outer thread 213;
an electrically insulative cap 22 mounted inside the first metal casing 21 and defining therein a first receiving chamber 221 and a second receiving chamber 222;
a metal probe 24 axially forwardly extending from the center of the front side of the electrically insulative cap 22 and having an air through hole 241 extending from the periphery to the bottom end thereof in air communication with the first receiving chamber 221;
a metal spring plate 23 mounted on the metal probe 24 inside the first metal casing 21 and stopped between the first O-ring 214 and the electrically insulative cap 22, having a center through hole 231 for the passing of the metal probe 24;
a flexible air pressure chamber 25 formed of an electrically insulative flexible diaphragm 251, which is inserted into the first receiving chamber 221 of the electrically insulative cap 22, and a metal conductor member 252, which is mounted in the electrically insulative flexible diaphragm 251 and stopped at the bottom end of the metal probe 24;
a negative pole metal spring member 26 provided at the bottom side of the metal conductor member 252;
a metal holder member 27 mounted in the first receiving chamber 221 of the electrically insulative cap 22 and having a front receptacle 271, which accommodates the negative pole metal spring member 26 and has a front edge 272 pressed on the periphery of the electrically insulative flexible diaphragm 251 to keep the first receiving chamber 221 of the electrically insulative cap 22 in an airtight status;
a battery cell (Li-ion battery) 28 mounted in the second receiving chamber 222 of the electrically insulative cap 22 with the positive terminal 281 maintained in contact with the metal holder member 27;
a second metal casing 29, which has an inner thread 291 threaded onto the second outer thread 213 of the first metal casing 21;
a control IC board 292 mounted inside the second metal casing 29 and kept in contact with the bottom edge 215 of the first metal casing 21; and
a positive pole metal spring member 293 installed in the control IC board 292 and stopped against the negative terminal 282 of the battery cell 28.
The locking device 30 comprises a locknut 31 and a packing plate 32. As shown in
After connection of the front neck 211 of the first metal casing 21 to the air valve 40, the locknut 31 is threaded onto the first outer thread 212 to lock the tie pressure detector 20 to the air valve 40 (see
After locking of the tire pressure detector 20, the metal probe 24 is pressed on the center control valve rod 42 of the air valve 40 to let air pass from the inside of the tire through the air through hole 241 into the flexible air pressure chamber 25 in the first receiving chamber 221, causing the electrically insulative flexible diaphragm 251 to displace downwards and to disconnect the metal conductor member 252 from the metal probe 24. This status means the tire pressure is within the normal range. Because the flexible diaphragm 251 is electrically insulative, the battery cell 28 is off at this time, and the control IC board 292 does no work and gives no signal. According to this embodiment, the electrically insulative flexible diaphragm 251 is made of rubber for the advantages of high sensitivity and durability. Further, the electrically insulative flexible diaphragm 251 holds the metal conductor member 252 in place to form the desired flexible air pressure chamber 25 that is easy to install.
Referring to
Referring to
According to the present invention, one receiver and alarm unit 50 can be used with four tire pressure detectors 20. In this case, the four tire pressure detectors 20 are respectively installed in the four wheels of the vehicle, and the receiver and alarm unit 50 has four indicator lights 540 corresponding to the four tire pressure detectors 20. Preferably, LEDs are used for the indictor lights 540.
Referring to
Referring to
Referring to
As indicated above, the invention uses a tire pressure detector 20, a locking device 30, and a receiver and alarm unit 50 to form the desired tire pressure detector and alarm system. The tire pressure detector 20 is highly reliable and durable and does not produce a false signal during high speed rotation. The arrangement of the electrically insulative cap 22, the metal spring plate 23, the metal probe 24 and the flexible air pressure chamber 25 form an open circuit when the air pressure of the tire is within the normal range. The circuit is kept off after disconnection of the tire pressure detector 20 from the air valve 40. The locking device 30 locks the tire pressure detector 20 to the air valve 40, preventing disconnection of the tire pressure detector 20 from the air valve 40 by an external force. Further, the receiver and alarm unit 50 can directly be connected to the socket for cigarette lighter of the vehicle to obtain the necessary working voltage of the car battery power supply.
A prototype of tire pressure detector and alarm system has been constructed with the features of FIGS. 3˜10. The tire pressure detector and alarm system functions smoothly to provide all of the features discussed earlier.
Although a particular embodiment of the present invention has been shown and described, it will be understood that various modifications and changes could be made thereunto without departing from the spirit and scope of the invention disclosed.
