Patent Application
20140064989
The present invention relates to a high-pressure fuel pump device for supplying fuel stored in a fuel tank to an injector.
In two-wheeled motor vehicles, namely, in motorcycles, a fuel injection system using an injector to inject fuel has come to be widely used in place of carburetor. In such fuel injection systems, fuel pressurized by means of a plunger-type high-pressure fuel pump device is supplied to the injector attached to the engine.
Since the plunger-type high-pressure fuel pump device is configured to increase the pressure of fuel for delivery by moving the plunger, however, it cannot be expected to perform the function of sucking up fuel stored in the fuel tank. Thus, in motorcycles, the plunger-type high-pressure fuel pump device is located at a lower level than the fuel tank so as to utilize the weight of fuel to suck in the fuel, or is arranged within the fuel tank to directly suck in the fuel stored in the fuel tank.
In motorcycles in particular, many devices such as the fuel tank, engine and transmission are densely arranged in a limited space surrounded by the front wheel, the fuel tank, the rear wheel and the seat, and therefore, the high-pressure fuel pump device, which is single in number and thus is easier to secure a space for fitting, is used to supply fuel stored in the fuel tank to the injector.
With the recent diversification of motorcycles, the high-pressure fuel pump device also is required to cope with such diversification and sometimes needs to be mounted at a location near the fuel tank or the engine where the high-pressure pipe can be shortened in length.
However, the high-pressure fuel pump device cannot be expected to perform the function of sucking up fuel stored in the fuel tank as stated above, and thus it is often the case that the high-pressure fuel pump device cannot be mounted on motorcycles.
In four-wheeled motor vehicles (automobiles), a feed pump device is provided separately from the high-pressure fuel pump device to suck up fuel stored in the fuel tank, and the fuel is supplied from the feed pump device to the high-pressure fuel pump device, as disclosed in Patent Document 1. In such four-wheeled motor vehicles, to avoid heat damage, the feed pump device is usually arranged within the fuel tank to be cooled by the fuel in the fuel tank, and the fuel is supplied to the high-pressure fuel pump device while suppressing vaporization of the fuel. This configuration could be applied to motorcycles as well.
Patent Document 1: Unexamined Japanese Patent Publication No. 7-12029
However, in the case of motorcycles, the space for outfit is very limited, unlike four-wheeled motor vehicles, and since the fuel tank, engine, injector and transmission are densely arranged in the limited space, it is difficult to secure a space for installing both the high-pressure fuel pump device and the feed pump device (two pump devices). Since the high-pressure fuel pump device and the feed pump device are driven by respective different drive sources in particular, a space for fitting the drive sources is required, and in addition, the feed pump device needs to be immersed in fuel for suppressing vaporization of the fuel. Thus, in the case of motorcycles in which only a limited space is available for outfitting, it is difficult to mount the two devices, namely, the high-pressure fuel pump device and the feed pump device, at respective different locations that may vary depending on the model of motorcycle.
Even if both of the high-pressure fuel pump device and the feed pump device could be fitted, it is highly possible that the fuel passage connecting the feed pump device and the high-pressure fuel pump device is located in the vicinity of the engine, and since the fuel being delivered is liable to vaporize, it is difficult to supply fuel in a stable manner.
An object of the present invention is to provide a high-pressure fuel pump device which is a single compact device enhanced in outfitting flexibility and capable of suppressing vaporization of fuel and which can perform a series of operations from the suction of fuel stored in a fuel tank through to the supply of high-pressure fuel to an injector.
To achieve the object, the present invention provides a high-pressure fuel pump device comprising: a plunger-type high-pressure pump unit including a plunger driven by a drive source, the high-pressure pump unit being configured to pressurize fuel and discharge the pressurized fuel as the plunger makes reciprocating motion; a diaphragm-type supply pump unit including a diaphragm capable of oscillating in conjunction with the reciprocating motion of the plunger, the supply pump unit being configured to suck in fuel in a fuel tank and supply the fuel to the high-pressure pump unit as the diaphragm oscillates; and a fuel return unit provided in the supply pump unit and configured such that, out of the fuel supplied to the high-pressure pump unit, surplus fuel that is not sucked into the high-pressure pump unit is returned to the fuel tank by the fuel return unit (claim 1).
Preferably, the diaphragm of the supply pump unit is coupled to the drive source through an actuator shaft, and the plunger of the high-pressure pump unit and the actuator shaft of the diaphragm are arranged coaxially with each other (claim 2).
Also, preferably, the plunger of the high-pressure pump unit has a passage formed therein, and the supply pump unit is configured to guide the fuel to the high-pressure pump unit through the passage (claim 3).
Further, the fuel return unit preferably includes a return path configured to pass the fuel to be returned, and a return valve arranged in the return path and configured to flow surplus fuel that is not sucked into the high-pressure pump unit (claim 4).
Preferably, the high-pressure pump unit and the supply pump unit are arranged on one side of the diaphragm, and the drive source is arranged on an opposite side of the diaphragm (claim 5).
According to the present invention, the high-pressure fuel pump device has a compact structure in which the high-pressure pump unit and the supply pump unit are integrated and share a single drive source, a structure in which the supply pump unit and the high-pressure pump unit are located close to each other to suppress heat damage attributable to heat from the engine, and a structure permitting vapor contained in the fuel to be returned to the fuel tank (claim 1).
With the high-pressure fuel pump device, therefore, a series of operations from the suction of fuel stored in the fuel tank through to the supply of high-pressure fuel to the injector can be stably performed by a single device which is compact in size and has enhanced outfitting flexibility. Moreover, fuel vapor, if generated in the process of delivery to the high-pressure pump unit, is returned together with surplus fuel to the fuel tank. Accordingly, the high-pressure fuel pump device can be installed at a desired location of a motorcycle as in the vicinity of the engine, fuel tank or other component parts, without regard to vaporization of fuel, and thus is best suited for use in motorcycles with many constraints.
The plunger of the high-pressure pump unit and the actuator shaft of the diaphragm are arranged coaxially with each other, and accordingly, the two pump units can be driven by a single drive source, making it possible to reduce the number of component parts as well as cost and to save space (claim 2).
The interior of the plunger is less affected by heat from outside (engine and the like), and the high-pressure fuel pump device is configured such that fuel passes through the interior of the plunger, whereby fuel can be prevented from being damaged by heat while being delivered from the supply pump unit to the high-pressure pump unit, making it possible to further reliably suppress vaporization of the fuel being supplied to the high-pressure pump unit (claim 3).
In the high-pressure fuel pump device, the fuel return unit is constituted by the return path and the return valve, so that the fuel return unit can be simplified in structure (claim 4).
The drive source for driving the plunger is separated by the diaphragm from the pump section where the fuel passes, and it is therefore possible to prevent the fuel from leaking into the drive source (claim 5).
A first embodiment of the present invention will be described below with reference to
The motorcycle illustrated in
A fuel tank 11 and a seat 12 are placed on the main tube member 1 in the mentioned order from front to back. An acceleration/deceleration system including a brake pedal and a throttle grip (neither of which is shown) is provided on the right side of the main tube member 1, and a gearshift system including a clutch lever and a shift pedal (neither of which is shown) is provided on the left side of the main tube member 1.
The main tube member 1 includes a down tube member la extending downward therefrom. An engine, for example, a single-cylinder reciprocating engine 13 (hereinafter merely referred to as the engine 13) having a piston 13b fitted into a cylinder (not shown) for reciprocating motion, is placed in a space enclosed by the down tube member la and the fuel tank 11 (including the main tube member 1).
An injector 14b is inserted in an intake pipe 14a (communicating with the cylinder) of the engine 13 and capable of injecting fuel into the intake pipe 14a (or the cylinder). Although not illustrated, the injector 14b is connected to a control unit (not shown) including a microcomputer and other related elements so that fuel injection quantity and fuel injection timing may be controlled in accordance with the operating condition of the engine 13 (electronically controlled fuel injection mechanism).
A transmission 15 having a clutch mechanism (not shown) built therein is attached to a crankcase 13c of the engine 13. The output of the transmission 15 is connected to the rear wheel 9 through a power transmission member, for example, an endless chain member, not shown. Thus, the motorcycle is configured such that the rear wheel 9 is driven by the driving force generated by the engine 13.
A fuel supply system for supplying fuel to the injector 14b employs a high-pressure fuel pump device 17, which constitutes a central part of the present invention. The high-pressure fuel pump device 17, which has a fuel drawing function, draws up (sucks in) the fuel stored in the fuel tank 11, raises the fuel pressure, and supplies the high-pressure fuel to the injector 14b. The high-pressure fuel pump device 17 has a configuration such that, at which location around the fuel tank 11 or the engine 13 it is installed, the high-pressure fuel pump device 17 can stably suck in the fuel stored in the fuel tank 11 and supply the fuel from the installed location to the injector 14b.
Referring to
The body 19 is fixed to the fuel tank 11 in such a manner that, with the cover 25 and the lower case 23 inserted into a pump device-mounting hole 11b (shown in
The lower case 23, which is located inside the fuel tank 11, has incorporated therein a plunger-type high-pressure pump unit 31 for raising the pressure of the fuel, a diaphragm-type supply pump unit 33 for drawing up the fuel stored in the fuel tank 11, and a fuel return unit 34 for returning surplus fuel from the supply pump unit 33, as shown in
The lower case 23 has a hollow formed therein, and an upper end portion of the hollow is constituted by a recess 35 having a larger diameter than the rest of the hollow. The high-pressure pump unit 31 is fitted into the hollow extending downward from the recess 35.
The high-pressure pump unit 31 will be explained in more detail. As illustrated in
As shown in
A high-pressure chamber 47 constituted by the hollow is formed in the lower part of the lower case 23. The discharge valve 45 is situated between the high-pressure chamber 47 and the pressurizing chamber 41b. The discharge valve 45 is constituted by a check valve which permits fuel to flow only in a direction from the pressurizing chamber 41b toward the high-pressure chamber 47. For example, the discharge valve 45 is constituted by a check valve module having a ball valve element 48b and a valve spring 48c accommodated in a tubular valve chamber unit 48a.
As illustrated in
Specifically, as shown in
The high-pressure pump unit 31 is configured to pressurize fuel in the pressurizing chamber 41b and discharge the pressurized fuel to the high-pressure chamber 47, by making use of the reciprocating motion of the plunger 43, more particularly, by the action of the suction and discharge valves 43b and 45 that open and close in conjunction with the movement of the plunger 43.
As shown in
In connection with the regulator 54, reference sign 57 denotes a valve accommodation chamber extending from the boundary between the lower case 23 and the cover 25 to the bottom of the cover 25. The valve accommodation chamber 57 is a cylindrical space concentric with the high-pressure chamber 47. A tubular valve element 59 is accommodated in that portion of the valve accommodation chamber 57 which is located on the same side as the high-pressure chamber 47. The valve element 59 is configured to rest on a valve seat 49a, which is the opening edge of the high-pressure chamber 47, and is vertically displaceable along a pin 25a, as a guide, which protrudes from the inner bottom surface of the cover 25. Also, the valve element 59 is urged in the valve closing direction (the direction in which the valve element comes into close contact with the valve seat) by a valve spring 61 disposed in the cover 25. The space around the valve element 59 is divided by a diaphragm 63 extending from the boundary between the lower case 23 and the cover 25 to the outer peripheral surface of the valve element 59. Out of the divided spaces, the space a located on the same side as the high-pressure chamber 47 serves as a pressure regulating chamber. Communication passages, not shown, are formed in the valve element 59 so as to always communicate with the space a.
The other space b divided by the diaphragm 63 and located on the same side as the bottom of the cover 25 opens into the fuel tank 11 (at atmospheric pressure) via through holes 65 formed in the bottom of the cover 25, as shown in
As illustrated in
That is to say, the regulator 54 is configured to adjust the fuel pressure to a pressure suited for fuel injection through change of the opening of the valve element 59 in response to the fuel pressure and forced relief of the fuel pressure by the valve element 73. Needless to say, the regulator 54 serves also as an accumulator.
As shown in
On the other hand, the diaphragm-type supply pump unit 33 employs a pump mechanism which is driven by the common drive source (single motor 51) and in which a diaphragm 87 is oscillated in conjunction with the reciprocating motion of the plunger 43 shown in
As shown in
Also, as illustrated in
As shown in
Specifically, the return valve 107, which is, like the suction valve 91, a check valve module having a mushroom valve element 109b, a valve spring 109c and a valve guide 109d incorporated in a valve body 109a, is arranged in an internal passage of the return port 101, as shown in
As shown in
In the high-pressure fuel pump device 17, the high-pressure pump unit 31 and the supply pump unit 33 are arranged on the lower side (one side) of the diaphragm 87 whereas the motor 51 is arranged on the opposite upper side (other side) of the diaphragm 87 such that the motor 51 (drive source) and the pump section in which fuel flows are separated by the diaphragm 87. In
Operation of the high-pressure fuel pump device 17 is illustrated in
Referring to
When the plunger 43 ascends, negative pressure is generated in the pressurizing chamber 41b. Negative pressure is generated also in the diaphragm chamber 89.
At this time, the suction valve 43b built into the plunger 43 and the suction valve 91 in the diaphragm chamber 89 are both opened (return valve 107 is closed), as shown in
The supply pump unit 33 and the high-pressure pump unit 31 are located close to each other, and therefore, heat damage to the fuel can be minimized even if the fuel is subjected to heat from outside.
Subsequently, the plunger 43 begins to descend, whereupon the suction valve 43b built into the plunger 43 closes, as shown in
The plunger 43 descends further, and when the fuel pressure in the pressurizing chamber 41b exceeds the valve-opening pressure set by the valve spring 48c of the discharge valve 45, the discharge valve 45 opens, as shown in
Even if the fuel in the diaphragm chamber 89 contains vapor because of heat from the engine 13 or the like, such vapor is returned to the fuel tank 11 together with the recovered fuel (return fuel), whereby the fuel supply from the diaphragm chamber 89 to the high-pressure chamber 47 can be continued in a stable manner.
The fuel in the high-pressure chamber 47 is introduced at all times into the space a via the communication passages, not shown, formed in the valve element 59, and with the fuel pressure in the space a adjusted by the pressure regulating function of the diaphragm 63, the fuel is supplied from the space a to the discharge port 55 through the passage 81 and the pipe member 83 and then to the injector 14b via the high-pressure pipe 85. When the fuel pressure in the high-pressure chamber 47 reaches a predetermined pressure, the valve element 59 of the regulator 54 moves away from the valve seat 49a, as shown in
When the fuel pressure in the high-pressure chamber 47 becomes excessively high, the valve element 59 descends to an extent such that the pin 25a abuts against the valve element 73, as indicated by two-dot chain lines S in
Consequently, the high-pressure fuel pump device 17 can stably perform a series of operations from the suction of fuel from the fuel tank 11 through to the supply of high-pressure fuel to the injector 14b. In particular, the high-pressure fuel pump device 17 has a compact structure in which the high-pressure pump unit 31 and the supply pump unit 33 are integrated and share the single motor 51 as a drive source with the transmission member 49 and the plunger 43 coaxially arranged, a heat damage resistant structure in which the high-pressure pump unit 31 and the supply pump unit 33 are located close to each other to suppress heat damage, and a return structure for returning surplus fuel as well as vapor contained in the fuel to the fuel tank 11, whereby reduction in the number of component parts, reduction in cost, space efficiency and enhanced outfitting flexibility can be realized by a single device. Also, the supply pump unit 33 is provided to draw up fuel stored in the fuel tank 11, and accordingly, even while the amount of fuel remaining in the fuel tank 11 is small, the fuel can be reliably drawn up from the bottom of the fuel tank 11 and supplied to the injector 14b.
Since low-pressure fuel and fuel vapor, which is liable to be generated in the supply pump unit 33, are returned together with surplus fuel from the diaphragm chamber 89 to the fuel tank 11 by the fuel return unit 34, the high-pressure fuel pump device 17 can be installed at a desired location of a motorcycle with many constraints, regardless of the generation of vapor. For example, as shown in
Also, the supply pump unit 33 employs such a configuration that the fuel is guided to the high-pressure pump unit 31 via the internal passage 37a formed in the plunger 43, and accordingly, the fuel is less affected by external heat such as heat from the engine 13. It is therefore possible to prevent the fuel from being thermally damaged while flowing from the supply pump unit 33 to the high-pressure pump unit 31, and also to suppress generation of vapor from the fuel being supplied to the high-pressure pump unit 31.
The fuel return unit 34, in particular, can be simplified in structure because it uses only the return path 105 for receiving the fuel to be returned and the return valve 107 for letting the fuel out of the diaphragm chamber 89.
Further, in the high-pressure fuel pump device 17, the motor 51 (drive source) is arranged on one side of the diaphragm 87, and the high-pressure pump unit 31 and the supply pump unit 33 are arranged on the opposite side of the diaphragm 87. Since the motor 51 is separated from the pump section in which the fuel flows, it is possible to avoid damage to the motor 51 due to the fuel.
The present invention is not limited to the foregoing embodiments and may be modified in various ways without departing from the scope of the invention.
For example, in the above embodiments, the high-pressure fuel pump device is installed at the upper part of the fuel tank or in the vicinity of the injector. The location where the high-pressure fuel pump device is to be installed is not limited to such locations, and the fuel pump device may be installed at some other location.
Also, the reciprocating motion of the plunger may of course be attained by some other conversion mechanism than the one using the cam mechanism and the motor.
Further, the high-pressure fuel pump device of the present invention may be applied to other motor vehicles than motorcycles, such as automobiles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-108096 | May 2011 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2012/062150 | 5/11/2012 | WO | 00 | 11/5/2013 |
