Pulsation type diaphragm pump

Details Pulsation type diaphragm pump Pulsation type diaphragm pump

2001-02-22

2002-09-10

Wolfe, Willis R. (Department: 3747)

Internal-combustion engines

Charge forming device

With fuel pump

C417S395000, C123SDIG005

Reexamination Certificate

active

06446611

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pump for supplying a fuel to a two cycle engine or a four cycle internal combustion engine, in general, to the two cycle engine, and more particularly to a pulsation type diaphragm pump which is driven by a pressure pulsation generated within a crank case or within an intake manifold in accordance with an operation of the engine.
2. Description of the Conventional Art
A mixture at a predetermined rate of air and fuel produced by a carburetor placed in an intake passage extending to a combustion chamber of the engine from an air cleaner is supplied to a two cycle or four cycle compact internal combustion engine as a power source for a farm machine, an outboard motor, a light car or the like. As a pump for feeding a fuel in a fuel tank to the carburetor, there is widely used a pulsation type diaphragm pump having advantages such as a simple structure in comparison with a mechanical or electromagnetic pump and a characteristic of being driven with no mechanical loss.
An embodiment of an arrangement among the air cleaner, the carburetor, the two cycle engine and the pulsation type diaphragm pump is described in Japanese Utility Model Publication No. 97317/1977. Further, a detailed explanation of the pulsation type diaphragm pump is described in pages 36 to 40 of a bimonthly “Car Technology” issued by Tetsudo-Nihon-Sha, Tokyo, Japan on January 1983.
FIG. 7
is a vertical cross sectional view showing the same structure as a typical pulsation type diaphragm pump described in the above bimonthly. A pump diaphragm
52
and a cover body
53
are laid over one surface of a main body
51
of the pump, and a recess provided in the main body
51
and covered by the pump diaphragm
52
forms a pump chamber
54
. An inner portion of the cover body
53
partitioned from the pump chamber
54
by the pump diaphragm
52
forms a pulse chamber
55
, and a diaphragm spring
57
is received in the pulse chamber
55
.
A pulsator diaphragm
58
and a cap
59
are laid over another surface of the main body
51
, and two recesses provided in the main body
51
to be back to back with the first mentioned recess and covered by the pulsator diaphragm
58
form an intake chamber
60
and a discharge chamber
62
respectively. An inner portion of the cap
59
partitioned from the intake chamber
60
and the discharge chamber
62
by the pulsator diaphragm
58
form air chambers
64
communicated with an atmospheric air. Further, an intake valve
65
is provided between the intake chamber
60
and the pump chamber
54
, and a discharge valve
67
is provided between the pump chamber
54
and the discharge chamber
62
.
A pressure pulsation within a crank case or within an intake manifold generated in accordance with an operation of an engine, in general, a pressure pulsation within the crank case is introduced to the pulse chamber
55
from a pulse introduction port
56
provided in the cover body
53
so as to oscillate the pump diaphragm
52
in cooperation with the diaphragm spring
57
. A fuel stored in a fuel tank (not shown) flows from a fuel inlet
61
to a fuel outlet
63
through the intake chamber
60
, the intake valve
65
, the pump chamber
54
, the discharge valve
67
and the discharge chamber
62
due to an operation of the diaphragm
52
so as to be fed to a carburetor (not shown). The pulsator diaphragm
58
serves to smoothen the pulsation of the fuel in the intake chamber
60
and the discharge chamber
62
so as to improve an intake efficiency and a discharge efficiency.
The intake valve
65
and the discharge valve
67
are check valves placed on a bottom wall
51
a which sections between the pump chamber
54
of the main body
51
and the intake chamber
60
and between the pump chamber
54
and the discharge chamber
62
respectively. There are provided with valve seat ports
66
a
and
68
a
communicating the intake chamber
60
with the pump chamber
54
and the pump chamber
54
with the discharge chamber
62
respectively on the bottom wall
51
a
, and are structured such that bevel-shaped valve bodies
66
b
and
68
b
made of an elastic material are mounted on the bottom wall
51
a
so as to open and close the valve seat ports
66
a
and
68
a
respectively.
On the other hand, the pulsation type diaphragm pump is generally compact, and a diameter of the pump diaphragm
52
is ordinarily less than 10 cm. Accordingly, the valve bodies
66
b
and
68
b
of the intake valve
65
and the discharge valve
67
placed within the pump are significantly small, and there is a case that the valve seat ports
66
a
and
68
a
are hardly bend and deform largely enough to open largely so that a fuel flow amount required by the engine is secured.
As the intake valve and the discharge valve, there has been known a valve with a valve body being formed in a linearly oscillating plate shape instead of a bevel shape bending and deforming at an outer peripheral edge portion. This valve body can largely open the valve seat port. However, most of such valve bodies are provided with a closing valve spring for completely closing the valve and a spring receiver for holding the closing valve spring in cooperation with the valve body, in addition to a guide for linearly oscillating the valve body. Accordingly, the number of parts constituting the pump is large and all of these parts have small sizes, so that an assembling operation thereof is troublesome and needs a lot of assembling processes and labors, thereby preventing a production cost from being reduced.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to perform an opening and closing operation particularly suitable for an intake valve and a discharge valve in a pulsation type diaphragm pump provided with an intake chamber and a discharge chamber for a fuel, a pump chamber, a pump diaphragm oscillating due to a pressure pulsation generated in accordance with an operation of an engine so as to change a capacity of the pump chamber, a pulsation diaphragm smoothening a pulsation of the fuel generated in the intake chamber and the discharge chamber, an intake valve communicating or shutting the intake chamber with or from the pump chamber, and a discharge valve communicating or shutting the pump chamber with or from the discharge chamber.
Further, another object of the present invention is to reduce the number of parts constituting the intake valve and the discharge valve in the above mentioned pulsation type diaphragm pump and the number of assembling processes and labors therefor.
Further, the other object of the present invention is to make the intake valve and the discharge valve open and close normally for any engines so as to achieve a reliable pump function.
In accordance with the present invention, the intake valve is structured such that a valve seat having a valve seat port for communicating the intake chamber with the pump chamber protrudes into the inner portion of the pump chamber, and a valve body for opening and closing the valve seat port in cooperation with a seat surface of the valve seat is a portion opposing to the valve seat of the pump diaphragm. Further, the discharge valve is structured such that a valve seat having a valve seat port for communicating the pump chamber with the discharge chamber protrudes into the inner portion of the discharge chamber, and a valve body for opening and closing the valve seat port in cooperation with a seat surface of the valve seat is a portion opposing to the valve seat of the pulsator diaphragm.
The valve body of the intake valve is apart from the seat surface in an intake stroke in which the pump diaphragm is displaced in a direction to expand a capacity of the pump chamber, and is brought into contact with the seat surface and seated on the seat surface in a discharge stroke in which the pump diaphragm is displaced in a direction to compress the capacity of the pump chamber. Further, the valve body of the discharge valve is brought into contact with the seat surface in the intake s

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