Valve device

A check valve for opening/closing intake-side communication passages through which fuel passes, includes a pump body including a partition wall with the communication passages formed therein, a valve body supported by the partition wall, made of a flexible material, and formed into a plate shape, and a valve seat provided around opening portions of the communication passages on the partition wall and including a seat surface to abut against the valve body when the valve is closed, the seat surface including a groove having an opening-portion-side wall surface lying on an upstream side and an outer-side wall surface lying on a downstream side, the upstream and downstream sides being sides in a direction in which fluid passes between the valve body and the seat surface when the valve is opened, the outer-side wall surface having a gentler slope than a slope of the opening-portion-side wall surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2017-203622, filed on Oct. 20, 2017, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a valve device, particularly to a valve device for opening and closing a passage for fluid.

Description of the Related Art

Various valve devices for opening and closing a passage of fluid, such as a check valve used in a fuel pump of an engine, are known.

For example, a check valve for a fuel pump described in Japanese Patent Laid-Open No. 2003-90447 is provided at an opening portion of a communication passage that communicates with two chambers and through which fuel passes, the check valve including a disc-shaped flexible material such as a resin membrane as a valve body. In the valve body, its central portion is supported, and its outer circumferential portion is swingable. The valve body has a structure for opening and closing a plurality of opening portions arranged concentrically with the supported portion. Surrounding the opening portions, a valve seat is provided, the valve seat protruding toward the valve body. When a pressure on one of both sides of the valve body, the side opposite to the communication passage, exceeds a pressure on the communication passage side, the valve body and the valve seat come into contact with each other to seal the opening portions. In contrast, when the pressure on the communication passage side exceeds the pressure on the opposite side, the valve body and the valve are separated from each other to open the opening portions.

In a valve including a valve body made of a flexible-material-made plate member, such as one described in the above Literature, fluid passes between the valve body and a valve seat when the valve body is opened.

Now, if the fluid contains an entrained grain such as a foreign object, the grain can be caught between the valve body and the valve seat as the valve body is closed. In such a case, the valve body fails to seal the opening portions completely, and leakage may occur.

SUMMARY OF THE INVENTION

The present invention is made in light of such a problem. Its objective is to provide a valve device capable of preserving a stoppage function of its valve body even in a case of an admixture of a grain.

To achieve the objective, a valve device according to the present invention is a valve device for opening and closing a passage of fluid, the valve device including: a housing including a wall member including the passage; a valve body supported by the wall member, the valve body being made of a flexible material and formed into a plate shape; and a valve seat provided around an opening portion of the passage on the wall member and including a seat surface to abut against the valve body when a valve is closed, the seat surface including a groove having side surfaces on an upstream side and a downstream side in a direction in which the fluid passes between the valve body and the valve seat when the valve is opened, the side surface on the downstream side having a gentler slope than a slope of the side surface on the upstream side.

With the valve device according to the present invention, even when a grain such as a foreign object entrained in fluid is caught between the valve body and the valve seat when the valve is closed, the grain is trapped in the groove, which prevents a poor contact between the valve body and the valve seat when the valve is closed, enabling a valve closing function to be maintained.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1is a vertical cross-sectional view illustrating an internal structure of a fuel pump1, in which a valve device according to the present invention is used.

The fuel pump1according to the present embodiment is a fuel pump for supplying fuel to a fuel supply system of an engine from a fuel tank.

As illustrated inFIG. 1, the fuel pump1is a diaphragm fuel pump including a diaphragm2. The fuel pump1includes a pump body3, a bottom body4, a cover5, a diaphragm2, a membrane6, a first check valve7, and a second check valve8. The first check valve7and the second check valve8are check valves and each equivalent to the valve device according to the present invention. The pump body3, the bottom body4, and the cover5are equivalent to a housing according to the present invention.

The pump body3, the bottom body4, and the cover5are formed of, for example, a resin. The pump body3includes a partition wall3atherein and is formed into a substantially cylindrical shape with its both lateral sides opened. The bottom body4is fixed to one of the lateral sides of the pump body3, sealing the one lateral side. The cover5is fixed to the other lateral side of the pump body3, sealing the other lateral side. The partition wall3ais equivalent to a wall member according to the present invention.

The diaphragm2and the membrane6are each made of, for example, NBR rubber and formed into a thin disk shape. The diaphragm2is sandwiched between the pump body3and the bottom body4. The membrane6is sandwiched between the pump body3and the cover5.

Between the diaphragm2and the partition wall3aof the pump body3, a pump chamber9is provided. Between the diaphragm2and the bottom body4, a pulse chamber10is provided. That is, the diaphragm2separates the pump chamber9and the pulse chamber10from each other. The bottom body4includes a pulse introduction port11for introducing a pressure into the pulse chamber10, and through the pulse introduction port11, a pulsing pressure pulse such as intake air is introduced into the pulse chamber10from an intake manifold or a crank chamber of an engine (not illustrated).

Between the membrane6and the partition wall3aof the pump body3, a fuel intake chamber12and a fuel discharge chamber13are provided. Between the membrane6and the cover5, an intake-side dumping chamber14and a discharge-side dumping chamber15are provided, the intake-side dumping chamber14being opposite to the fuel intake chamber12across the membrane6, the discharge-side dumping chamber15being opposite to the fuel discharge chamber13across the membrane6. That is, the membrane6separates the fuel intake chamber12and the intake-side dumping chamber14from each other, and separates the fuel discharge chamber13and the discharge-side dumping chamber15from each other.

The pump body3includes an inlet16communicating with the fuel intake chamber12and an outlet17communicating with the fuel discharge chamber13. The inlet16is connected to a fuel tank (not illustrated), and the outlet17is connected to a fuel supply system such as a fuel injection valve of an engine.

The partition wall3aof the pump body3includes intake-side communication passages20and discharge-side communication passages21, the intake-side communication passages20connecting the fuel intake chamber12and the pump chamber9, the discharge-side communication passages21connecting the pump chamber9and the fuel discharge chamber13. The intake-side communication passages20and the discharge-side communication passages21are each equivalent to a passage according to the present invention.

The first check valve7is provided in the partition wall3aof the pump body3and has a function of opening/closing the intake-side communication passages20. The first check valve7has a function of allowing fuel to pass only from the fuel intake chamber12to the pump chamber9.

The second check valve8is provided in the partition wall3aof the pump body3and has a function of opening/closing the discharge-side communication passage21. The second check valve8has a function of allowing fuel to pass only from the pump chamber9to the fuel discharge chamber13.

The first check valve7and the second check valve8are supported by rubber-made grommets22and23to be fixed to the pump body3.

FIG. 2is a vertical cross-sectional view illustrating the fuel pump1with fuel being taken therein.FIG. 3is a vertical cross-sectional view illustrating the fuel pump1with fuel being discharged therefrom. In FIG.2andFIG. 3, drawn arrows indicate a moving direction of fuel, intake air, and the like.

In the fuel pump1configured as described above, when a pressure pulse is introduced in the pulse chamber10as an engine operates, and the pulse chamber10is placed under a negative pressure, as illustrated inFIG. 2, the diaphragm2moves toward the bottom body4, rightward inFIG. 2. As a result, the pump chamber9is placed under a negative pressure, which causes the first check valve7open and the second check valve8close, so that fuel moves from the fuel intake chamber12to the pump chamber9.

When the pulse chamber10is placed under a positive pressure, as illustrated inFIG. 3, the diaphragm2moves away from the bottom body4, leftward inFIG. 3. As a result, the pump chamber9is placed under a positive pressure, which causes the first check valve7to close and the second check valve8to open, so that fuel moves from the pump chamber9to the fuel discharge chamber13.

By supplying pressure pulses alternating positive and negative pressures from the engine to the pulse chamber10, the diaphragm2alternates the movements illustrated inFIG. 2andFIG. 3, so that fuel is taken from the inlet16and discharged from the outlet17.

The membrane6cushions steep changes in pressure in the fuel intake chamber12and the fuel discharge chamber13. This stabilizes the discharge of fuel from the fuel discharge chamber13of the fuel pump1.

Next, the first check valve7will be described in detail with reference toFIG. 4toFIG. 9.

FIG. 4is a top view of the pump body3with the first check valve7and the second check valve8.FIG. 5is a vertical cross-sectional view illustrating a cross-sectional shape of the first check valve7closed.FIG. 6is a vertical cross-sectional view illustrating a cross-sectional shape of the first check valve7opened.FIG. 4is a diagram of the first check valve7and the second check valve8provided in the pump chamber3viewed from a pump chamber9side.FIGS. 5 and 6are cross-sectional views taken along the line A-A drawn inFIG. 4. Arrows drawn inFIG. 6indicate moving directions of fuel.

As illustrated inFIGS. 4 and 5, the first check valve7provided in the partition wall3aincludes a valve body7a, which has an annular thin plate shape and a flexibility such as that of a resin plate. The valve body7ais supported to the partition wall3aat its center portion by the rubber-made grommet22.

There are a plurality of intake-side communication passages20provided in the partition wall3aaround the grommet22and spaced apart in a circumferential direction. On a wall surface of the partition wall3aon the pump chamber9side, a valve seat7bis provided on an outer side of the intake-side communication passages20, the valve seat7bprotruding in a ring shape and including a top surface that serves as a seat surface. All opening portions of the intake-side communication passages20and the valve seat7bare covered with the valve body7a.

The second check valve8includes a valve body8amade of the same material and having the same shape as the valve body7a. The valve body8ais similarly supported to the partition wall3aat its center portion by the grommet23. There are a plurality of discharge-side communication passages21provided around the grommet23and spaced apart in a circumferential direction, as with the intake-side communication passages20. In the second check valve8, the valve body8aand the valve seat are provided not on the pump chamber9side but on a fuel discharge chamber13side that is opposite to the pump chamber9, which differs from the first check valve7.

As illustrated inFIG. 5, in the first check valve7, when a pressure in the pump chamber9is higher than that in the fuel intake chamber12, an outer circumferential portion of the valve body7aabuts against the valve seat7bof the partition wall3a. This closes the opening portions of the intake-side communication passages20with the valve body7a, blocking an inflow of fuel from the pump chamber9to the fuel intake chamber12.

In contrast, as illustrated inFIG. 6, when a pressure in the fuel intake chamber12is higher than that in the pump chamber9, an outer circumferential portion of the valve body7abends towards the pump chamber9side. As a result, the outer circumferential portion of the valve body7aseparates from the valve seat7b. Fuel in the fuel intake chamber12therefore passes from the intake-side communication passages20through between the valve body7aand the valve seat7binto the pump chamber9.

FIG. 7is a top view illustrating a shape of the valve seat7b.FIG. 7illustrates a shape of a wall surface of the partition wall3aon the pump chamber9side.FIG. 8is an enlarged cross-sectional view taken along the line B-B ofFIG. 7.FIG. 9is an explanatory diagram illustrating how a grain is ejected when the valve is opened. Arrows drawn inFIG. 9indicate moving directions of fuel or a grain.

As illustrated inFIGS. 7 and 8, the ring-shaped valve seat7bsurrounding the opening portions of the intake-side communication passages20includes a plurality of grooves30on its upper surface, the grooves each having a ring shape. The grooves30are provided concentrically with the ring-shaped valve seat7b, and disposed spaced apart from each other in a radial direction.

The grooves30each have a depth of, for example, about 0.2 to 0.4 mm. The grooves30each have a cross section in a substantially triangular shape. The grooves30therefore make the cross section of the valve seat7bserrate. A bottom of each groove30forms an edge portion with a chamfer of about R0.1 to 0.2 mm.

A side surface of each groove30on an intake-side communication passage20side, that is, an opening-portion-side wall surface30abeing an inner side surface of the groove30is formed to be perpendicular to the seat surface of the valve seat7b. A side surface of each groove30on an opposite side to the intake-side communication passage20side, that is, the outer-side wall surface30bbeing an outer side surface of the groove30is formed into a gentle slope inclined from the opening-portion-side wall surface30aat an angle about 60 degrees. Between adjacent grooves30, a flat surface30cbeing about 0.5 mm in width is secured for ensuring a sheet property.

FIG. 9is an explanatory diagram illustrating how a grain is ejected.FIG. 9illustrates a state of the valve seat7band the valve body7awhen the valve is opened, as well as an example of movements of fuel and a grain in a form of arrows.

When a pressure in the fuel intake chamber12is higher than that in the pump chamber9to open the first check valve7, fuel in the fuel intake chamber12moves from the intake-side communication passages20through between the valve body7aand the valve seat7boutward in a radial direction of the valve body7a, as illustrated inFIG. 9.

In a case of a valve device including a typical valve seat and valve body, if a grain such as a foreign object is caught between the valve seat and the valve body, the valve seat and the valve body may fail to come into close contact with each other to allow a flowing path of fluid to establish between the valve seat and the valve body, which may result in a leakage of the fluid. When the leakage occurs in the first check valve7of the fuel pump1as described above, a function of the first check valve7deteriorates, which may cause fuel to flow back from the pump chamber9to the fuel intake chamber12. This compromises an efficiency of the fuel pump1.

Even when a grain such as a foreign object is caught between the valve seat7band the valve body7aas the valve is closed, the provision of the grooves30in the valve seat7bas in the first check valve7according to the present embodiment allows the grain to move into a groove30, securing a close contact between the valve seat7band the valve body7a. As a result, it is possible to reduce occurrence of leakages due to a grain caught as the first check valve7is closed, enhancing a valve closing function. Being about 0.2 to 0.4 mm, the depth of the grooves30provided in the valve seat7bis enough to trap a grain such as a foreign object in a groove30.

In the present embodiment, an outer-side wall surface30bof each groove30on an opposite side to the intake-side communication passage20, that is, a side surface of the groove30on a downstream side of a fuel passing direction is formed into a gentle slope with an angle of about 60 degrees, which makes it easy for a grain trapped in a groove30to move toward the outer-side wall surface30b. Accordingly, when the valve body7ais opened, it is possible to move a grain in a groove30and ejected it outward in the radial direction as fuel passes between the valve body7aand the valve seat7b. It is therefore possible to maintain the valve closing function of the first check valve7.

Forming the outer-side wall surface30bof each groove30to be gently inclined can prevent a passing speed of fuel from decreasing due to the provision of the grooves30while avoiding fuel passing between the valve seat7band the valve body7aoutward in the radial direction from being hindered as much as possible.

Since the opening-portion-side wall surface30aof each groove30on the intake-side communication passage20side is formed to be perpendicular to the seat surface of the valve seat7b, it is possible to prevent backflow leakages of fuel from an outer circumferential portion side to the intake-side communication passage20side between the valve seat7band the valve body7a.

The descriptions of the embodiments will be finished here, but aspects of the present invention are not limited to the above embodiments. For example, although the above embodiment describes the configuration of the first check valve7, the second check valve8may be provided with grooves30on its valve seat on the fuel discharge chamber13side, the grooves each having the same shape as in the first check valve7.

Although the present embodiment is an application of the present invention to the first check valve7for controlling a flow of fuel, the present invention is also applicable to a check valve for controlling a flow of liquid other than fuel.

Although the ring-shaped grooves30are provided in the above embodiment on the ring-shaped valve seat7bprovided on the periphery of the opening portions of the intake-side communication passages20, the present invention is applicable even to a valve device including a rectangular opening portion and a rectangular valve body formed of a flexible material, such as a reed valve. Also in this case, providing grooves on its valve seat at a location where fluid passes in one direction between the valve body and the valve seat as the valve is opened. The grooves may each have any shape as long as the shape extends in a direction substantially perpendicular to a fluid passing direction.

The present invention may be applied to a check valve used in systems other than fuel pumps. The present invention is widely applicable to even a valve device other than a check valve as long as the valve device has a structure in which a valve is opened with its valve body of flexibility brought into close contact with its valve seat.