Expansible chamber devices – With releasable stop or latch means to prevent movement of... – Means includes element interfitting between working member...
Reexamination Certificate
2001-03-15
2003-01-21
Look, Edward K. (Department: 3745)
Expansible chamber devices
With releasable stop or latch means to prevent movement of...
Means includes element interfitting between working member...
C092S015000
Reexamination Certificate
active
06508161
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a piston pump which is adapted for use in inflating a balloon, a yo-yo balloon, a bag, etc.
As for the means for inflating a balloon, a yo-yo balloon, a bag, etc. by introducing air or water into them, a simplified piston pump is known wherein a piston inserted into a cylinder is reciprocatively moved several times depending on the size of the balloon, etc. so as to inhale air or water into the cylinder and exhale it out of the cylinder through the nozzle thereof. In order to enable the piston of the pump to be reciprocatively moved safely and effectively, it is required that the piston is prevented from slipping out of the cylinder and that the shaft of piston is prevented from being decentered. If the piston slips out of the cylinder during the pumping operation of the pump, the operation of the piston pump is caused to interrupt, thus wasting the time for the inflation operation of the balloon, etc. On the other hand, if the shaft of piston is decentered on the occasion of reciprocative movement thereof, not only the reciprocative movement of the piston becomes difficult, but also a gap is caused to generate between the piston and the cylinder, thus deteriorating the function of the piston pump.
In most of the conventional piston pumps, the prevention of slipping-out of piston and the decentering of the piston shaft are effected by making use of a bearing cap. Namely, the bearing cap is a cap which fits on the cylinder and is provided at the center thereof with a through-hole for allowing the piston shaft to pass through, thus functioning as a bearing for the piston shaft. When a piston is attached to the piston shaft, the piston is caused to impinge against this bearing cap, thereby preventing the piston from slipping out of the cylinder. However, since the bearing cap is employed, the piston or operating grip is required to be attached to the piston shaft after the piston shaft has been inserted into the bearing cap. Therefore, the piston, piston shaft and operating grip are prepared separately, thus increasing the number of parts and also taking a lot of time for the assembling of them, resulting in an increase in manufacturing cost.
For example, Japanese Utility Model Unexamined Publication S56-155,862, Japanese Patent Unexamined Publication H7-310,649, and U.S. Pat. No. 5,655,890 set forth respectively a simplified piston pump of this kind.
Namely, Japanese Utility Model Unexamined Publication S56-155,862 discloses a piston pump which is featured in that the cylinder is made transparent, thereby making it possible to visually recognize the quantity of water introduced into the cylinder. Japanese Patent Unexamined Publication H7-310,649 discloses a piston pump which is featured in that the piston is molded from plastic material, thereby improving the sealing property as well as the smooth movement thereof relative to the cylinder. U.S. Pat. No. 5,655,890 discloses a piston pump which is featured in that both piston and cylinder are respectively provided with a one-way valve. However, since all of these known piston pumps utilize a bearing cap, they would accompany the same problem that the number of parts is increased and a lot of time is required for the assembling of them, resulting in an increase in manufacturing cost.
There is also known a simplified piston pump which has no bearing cap among the simplified piston pumps which are now available in the market. According to this piston pump, the piston shaft is of a cylindrical configuration, so that the outer peripheral surface of piston shaft is continuously contacted with the inner surface of the cylinder, thereby preventing the piston shaft from being decentered. This piston pump however is accompanied with a problem that since the cylindrical piston shaft is always contacted with the inner surface of the cylinder, it is impossible to provide the piston pump with means for allowing it to be contacted with the piston so as to prevent the piston from being slipped out.
BRIEF SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a simplified piston pump which employs no bearing cap, nevertheless, is capable of preventing the piston from slipping out of the cylinder and also capable of preventing the shaft of piston from being decentered. It is now made possible according to this piston pump to reduce the number of parts, to simplify the manufacturing process and to greatly save the manufacturing cost thereof.
The bearing cap according to the conventional simplified piston pump functions in two ways, i.e. for preventing the piston from slipping out of the cylinder and for preventing the shaft of piston from being decentered.
Therefore, the present inventors have made an extensive study for developing a simplified piston pump which has no bearing cap, but nevertheless, is capable of exhibiting the functions that the conventional bearing cap could provide.
First of all, it has been made possible by the present inventors to prevent the piston from slipping out by forming a protruded portion on the inner wall of proximal end portion of the cylinder. Due to the existence of this protruded portion, the piston is caused to impinge against this protruded portion even if it is tried to pull and disengage the piston from the cylinder, thereby making it possible to prevent the piston from inadvertently slipping out.
Then, it has been studied by the present inventors to realize the prevention of the decentering of piston shaft without necessitating the employment of the bearing cap. According to the aforementioned piston pump having no bearing cap, the piston shaft thereof is made cylindrical so as to make it entirely contact with the inner surface of the cylinder. It is certainly possible in this case to prevent the decentering of the piston shaft, but it is impossible to form a protrusion on the inner surface of the cylinder as proposed by the present invention. Under the circumstances, it has been intensively studied to find out a structure which enables the piston shaft to reciprocatively move even if the protrusion for preventing the slipping-out of piston is formed on the inner surface of the cylinder. As a result, it has been resulted in the invention of a piston shaft having a structure wherein the outer surface of the piston shaft is contacted with the inner surface of the cylinder so as to prevent the decentering of the piston shaft and wherein a groove is formed thereon so as to ensure the reciprocative movement of the piston. More specifically, by constructing the piston shaft in such a manner that irrespective of where the piston shaft is located within the reciprocating region thereof, the outer surface of the piston shaft is partially contacted with the inner surface of the cylinder so as to prevent the axial center of the piston shaft from being dislocated, it becomes possible to prevent the decentering of the piston shaft. For example, if the piston shaft is made into a triangular columnar configuration which is designed to be contacted with the inner surface of the cylinder, three ridge lines corresponding to the peaks of the triangular configuration are always caused to contact with the inner surface of the cylinder irrespective of the location of the piston shaft, thereby preventing the axial center of the piston shaft from being dislocated and hence preventing the decentering of the piston shaft.
Further, by forming the groove of the piston shaft in such a manner that it extends linearly and parallel with the reciprocative moving direction of the piston shaft, the protrusion formed on the inner surface of the cylinder for the prevention of the slipping-out of the piston is allowed to pass through the groove of the piston shaft. Therefore, even if the protrusion is formed on the inner surface of the cylinder, the piston is enabled to reciprocatively move inside the cylinder. It is now possible, through the employment of the piston shaft of the present invention, to prevent the decentering of the piston shaft and to f
Suzuki Takayuki
Takamura Teruo
Lazo Thomas E.
Look Edward K.
Suzuki Latex Industry Co., Ltd.
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