1. Field of the Invention
The present invention relates to tire pumps and, more particularly, to such a tire pump that produces a warning sound when the tire pressure reached a predetermined set value.
2. Description of the Related Art
When inflating the tire of a vehicle with a tire pump, the operator may check the pressure status of the tire, preventing an excessively high or low pressure that affects safety driving of the vehicle. A tire pump for this purpose may be equipped with a pressure gage. When pumping air into the tire, the operator has to visually check the reading of the tire gage. If a tire pump without pressure gage is used to pump air into the tire of a motor vehicle, the user may have to press the tire with the hand in order to check the pressure status of the tire. There is known another structure of tire pump that has tire pressure control means that automatically discharge pumped air to the atmosphere when the inside air pressure of the tire reached a predetermined set value. Either one of the aforesaid conventional tire pumps is used, the user needs to check the saturated pressure status of the tire with the eyes or the hand, or by means of recognizing discharging status of air from one end of the barrel.
Therefore, it is desirable to provide a tire pump that eliminates the aforesaid problem.
It is the primary objective of the present invention to provide a tire pump, which gives a warning sound when the tire pressure reaches a predetermined set value.
To achieve this objective of the present invention, the tire pump comprises a hollow barrel, a pump plunger, an air tube, an air nozzle, a regulating chamber, a regulating valve assembly, and an air whistle. The hollow barrel has an inside space. The pump plunger is provided at a bottom end thereof with a pump piston that is slidably inserted into the inside space of the barrel for pumping air. The air tube is connected to an end of the barrel in air communication with the inside space of the barrel. The air nozzle is provided at an end of the air tube. The regulating chamber is defined in between the barrel and the air nozzle and provided with a relief port. The regulating valve assembly has a regulating tube movable in the regulating chamber between a sealing position and a relief position. The air whistle is mounted in the relief port for producing a sound when the regulating tube shifted to the relief position where a flow of air passes from the inside space of the barrel to the relief port through the regulating chamber.
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The regulating valve assembly 60 is designed to be mounted in a regulating chamber defined in between the barrel 11 and the air nozzle 50. The tire pump is designed to have a relief port in one side of the regulating chamber for regulating the inside air pressure of the air tube 40. According to this embodiment, the regulating chamber is the big air passage 31, and the relief port is the open end of the valve tube 30. As shown in
A regulating knob 65 is threaded into the relief port of the valve tube 30. A spring member, for example, a spiral spring 66 is mounted inside the valve tube 30 and stopped between the regulating knob 65 and the regulating tube 61. By means of rotating the regulating knob 65 to compress the spring member 66, the pressure from the regulating tube 61 to block the small air passage 32 is regulated.
Therefore, when shifted the regulating tube 61 to the sealing position, the regulating tube 61 closes the passage between the big air passage 31 and the small air passage 32 with a predetermined pressure, and the inside air of the barrel 11 is prohibited from passing through the through hole 33 and the big air passage 31 to the outside. As shown in
The air whistle 70 is mounted in the relief port. According to this embodiment, the air whistle 70 is a reed fastened to the regulating knob 65. When a flow of air passes through the big air passage 31 to the outside of the valve tube 30, the flowing air will pass over the regulating knob 65 and the air whistle 70, producing a clear sound.
By means of the aforesaid design, when the internal air pressure of the tire reached a predetermined pressure level set by the regulating valve assembly 60, air cannot be pumped into the tire. When continuously pumping the tire pump at this time, air will pass through the through hole 33 and the big air passage 31 to the outside and will simultaneously force the air whistle 70 to produce a clear sound. Therefore, it is not necessary to check the pumping status or to use a tire pressure gage to measure the internal air pressure of the tire when pumping.
Further, the air nozzle, the pump body, the handle, the air tube can be obtained from conventional designs, or substituted by equivalent component parts. Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. For example, the installation of the regulating chamber and the regulating valve assembly is not limited to the bottom side of the barrel, and any of a verity of voice generating means may be used to substitute for the air whistle. Accordingly, the invention is not to be limited except as by the appended claims.