Fuel pressurization device

Abstract

To compress fuel necessary for start-up to an engine to improve start-up property of the engine.SOLUTION: A fuel compression device 1 compresses start-up fuel, which is supplied from a priming pump 3, to an engine 2 via a solenoid valve 4. The fuel compression device 1 includes: a fuel chamber R supplied with fuel from the priming pump 3 and having a variable volume interior; and a spring 30 for biasing an elastic body 20 so as to reduce the volume of the fuel chamber R.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a fuel pressurizing device that pressure-feeds fuel to an engine for starting. [Background technology]

[0002] For example, in an engine unit mounted on a brush cutter or the like, a priming pump sends fuel for starting the engine to a carburetor, where the fuel accumulates. Then, when a recoil starter is activated, the fuel stored in the carburetor is sent into the engine by the engine's negative pressure. An engine unit with such a configuration is described, for example, in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-52593 Summary of the Invention [Problem to be solved by the invention]

[0004] In the engine unit described above, fuel is sent to the carburetor by the priming pump, and the fuel is sent into the engine by the negative pressure of the engine. In such an engine unit, in order to improve engine starting performance, it is necessary to supply the fuel required for starting the engine under pressure.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fuel pressurizing device that can pump fuel required for starting to the engine, thereby improving the startability of the engine. [Means for solving the problem]

[0006] The present invention is [1] "a fuel pressurizing device (1) provided in an engine unit (100) including a pump (3), a valve (4), and an engine (2), which pressurizes starting fuel supplied from the pump (3) to the engine (2) via the valve (4), the fuel pressurizing device (1) including: a fuel chamber forming portion (12, 20) which receives the fuel from the pump (3) and has a fuel chamber (R) whose volume is variable; and a spring (30) which biases the fuel chamber forming portion (12, 20) so as to reduce the volume of the fuel chamber (R)."

[0007] In this fuel pressurizing device (1), the fuel chamber forming portions (12, 20) are biased by the spring (30), so that the fuel supplied by the pump (3) is pressurized in the fuel chamber (R). Since the fuel needs to be pressurized, the valve (4) provided in the engine unit (100) is closed while the fuel is being supplied into the fuel chamber (R) by the pump (3). In this state, when the valve (4) provided in the engine unit (100) is opened to start the engine (2), the pressurized fuel is supplied to the engine (2). In this way, the fuel pressurizing device (1) pressure-feeds the fuel required for starting to the engine (2), thereby improving the startability of the engine (2).

[0008] The fuel pressurizing device (1) of the present invention may be [2] "the fuel pressurizing device (1) described in the above [1], wherein the fuel chamber forming portion (12, 20) includes an elastically deformable elastic body (20) at least in part, the volume of the fuel chamber (R) changes as the elastic body (20) deforms, and the spring (30) biases the elastic body (20)." In this case, the fuel pressurizing device (1) can easily change the volume of the fuel chamber (R) by using the elastic body (20).

[0009] The fuel pressurizing device (1) of the present invention may be [3] "the fuel pressurizing device (1) according to the above [1] or [2], wherein an overflow passage (L13) branching from the discharge passage (L12) is connected to a discharge passage (L12) through which the fuel delivered from the fuel chamber (R) passes, and an overflow valve (40) is further provided to switch the flow of the fuel in the overflow passage (L13) on and off." In this case, the fuel pressurizing device (1) can discharge excess fuel supplied into the fuel chamber (R) by the pump (3) via the overflow valve (40) and the overflow passage (L13).

[0010] The fuel pressurizing device (1) of the present invention may be [4] "the fuel pressurizing device (1) according to the above [3], wherein the overflow valve (40) includes a valve element (41) and a valve element spring (42) that biases the valve element (41) so as to block the flow of fuel through the overflow passage (L13)." In this case, the fuel pressurizing device (1) can set the volume of the fuel chamber (R) to a desired volume by adjusting the balance of the biasing forces of the spring (30) that biases the fuel chamber forming portion (12, 20) and the valve element spring (42) of the overflow valve (40). In other words, in the fuel pressurizing device (1), the fuel chamber (R) can be easily set to a desired volume simply by changing the balance of the biasing forces of the springs (30, 42) without making any changes to the fuel chamber forming portion (12, 20). This makes it possible to easily apply the fuel pressurizing device (1) to engines (2) even if the amount of fuel to be pumped for starting varies depending on the type of engine (2). [Effects of the Invention]

[0011] According to the present invention, the fuel required for starting can be pumped to the engine, thereby improving the startability of the engine. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing an engine unit provided with a fuel pressurizing device according to an embodiment. [Figure 2] FIG. 2 is a front view of the fuel pressurizing device. [Figure 3] FIG. 3 is a side view of the fuel pressurizing device as seen from the intake port side. [Figure 4] FIG. 4 is a cross-sectional view taken along line ABCA in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line ADEF in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line ABCA in FIG. 2, showing how fuel is supplied into the fuel chamber. [Figure 7] FIG. 7 is a cross-sectional view taken along line ADEF in FIG. 2, showing how the fuel supplied to the fuel chamber is discharged from the overflow passage. [Figure 8] FIG. 8 is a cross-sectional view taken along line ADEF in FIG. 2, showing how fuel in the combustion chamber is supplied to the engine through a discharge passage. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and redundant description will be omitted.

[0014] As shown in FIG. 1, a fuel pressurizing device 1 according to this embodiment is provided in an engine unit 100. The engine unit 100 may be mounted on a brush cutter or the like, for example. The engine unit 100 includes an engine 2, a priming pump (pump) 3, and a solenoid valve (valve) 4. The engine 2 may be a two-stroke engine, for example. Although not shown, the engine unit 100 may also include a fuel pump or carburetor, a recoil starter, or the like, that supplies fuel to the engine 2, as appropriate.

[0015] When starting engine 2, fuel pressurizing device 1 pressure-feeds starting fuel supplied from priming pump 3 to engine 2 (for example, into the crankcase or combustion chamber) via solenoid valve 4. The following description will focus on the configuration in which fuel pressurizing device 1 pressure-feeds starting fuel.

[0016] The priming pump 3 is operated by a user of the engine unit 100 to supply fuel from the fuel tank 5 to the fuel pressurizing device 1. Here, the priming pump 3 takes in fuel from the fuel tank 5 via a pipe L4 and supplies the fuel to the fuel pressurizing device 1 via a pipe L3.

[0017] The solenoid valve 4 switches between supplying and not supplying starting fuel from the fuel pressurizing device 1 to the engine 2. Here, the solenoid valve 4 is provided in a pipe L1 for supplying starting fuel from the fuel pressurizing device 1 to the engine 2. The solenoid valve 4 is switchable between an open state in which fuel can flow through the pipe L1 and a closed state in which the flow of fuel through the pipe L1 is blocked. The solenoid valve 4 is switched from the closed state to the open state when the engine 2 is started. For example, the solenoid valve 4 may be switched from the closed state to the open state in conjunction with the operation of a recoil starter that is operated when the engine 2 is started.

[0018] As shown in FIGS. 2 and 3, the fuel pressurizing device 1 takes in fuel supplied from the priming pump 3 through an inlet S1. The fuel pressurizing device 1 then discharges the taken-in fuel from an outlet S2 and pressure-feeds it to the engine 2. The fuel pressurizing device 1 also has an overflow outlet S3. The overflow outlet S3 discharges excess fuel taken in to the outside. A nipple N1, a nipple N2, and a nipple N3 are attached to the inlet S1, the outlet S2, and the overflow outlet S3, respectively. A pipe L3 (see FIG. 1) is connected to the nipple N1. A pipe L1 (see FIG. 1) is connected to the nipple N2. A pipe L2 (see FIG. 1) is connected to the nipple N3. The pipe L2 serves as a flow path for returning excess fuel discharged from the fuel pressurizing device 1 to the fuel tank 5.

[0019] More specifically, as shown in Figures 4 and 5, the fuel pressurizing device 1 includes a main body 10, an elastic body 20, a spring 30, and an overflow valve 40 (see Figure 5). In this embodiment, the main body 10 includes a first main body 11 and a second main body 12. The first main body 11 and the second main body 12 are each substantially plate-shaped. The first main body 11 and the second main body 12 are stacked on top of each other with a gasket G sandwiched therebetween and fixed to each other by a screw B1.

[0020] The first body portion 11 is provided with a hole 11a that penetrates in the overlapping direction of the first body portion 11 and the second body portion 12. The second body portion 12 is provided with a recess 12a in a portion facing the hole 11a of the first body portion 11.

[0021] The elastic body 20 is disposed so as to cover the recess 12a of the second main body portion 12. In this embodiment, the elastic body 20 is fixed by sandwiching the edge of the elastic body 20 together with the gasket G between the first main body portion 11 and the second main body portion 12. The elastic body 20 is an elastically deformable member. For example, the elastic body 20 is made of rubber or the like.

[0022] Here, fuel is supplied from priming pump 3 to between second main body portion 12 and elastic body 20. In other words, the space between the wall surface of recess 12a of second main body portion 12 and elastic body 20 becomes fuel chamber R to which fuel is supplied. Also, as described above, elastic body 20 is elastically deformable. Therefore, the volume of fuel chamber R changes as elastic body 20 deforms (see the difference between fuel chambers R in Figures 4 and 5).

[0023] Note that Fig. 4 shows a state in which no fuel is supplied into the fuel chamber R. Fig. 5 shows a state in which fuel is supplied into the fuel chamber R, compressing the spring 30 and increasing the volume of the fuel chamber R compared to the state shown in Fig. 4. In this way, second main body portion 12 and elastic body 20 constitute a fuel chamber forming portion that includes fuel chamber R to which fuel is supplied from priming pump 3 and whose volume is variable.

[0024] As shown in FIG. 4, the spring 30 is disposed in the hole 11a of the first main body portion 11. The spring 30 is a compression spring. A substantially plate-shaped spring retainer 31 is attached to the outer surface of the first main body portion 11 with screws B2. The spring retainer 31 covers the hole 11a of the first main body portion 11. One end of the spring 30 abuts against the elastic body 20, and the other end of the spring 30 abuts against the spring retainer 31. In other words, the spring 30 biases the elastic body 20 toward the second main body portion 12 so as to reduce the volume of the fuel chamber R. In this way, when fuel is supplied into the fuel chamber R as shown in FIG. 5, the spring 30 applies pressure to the fuel in the fuel chamber R. Note that a spring contact 21 attached to the elastic body 20 may be provided between the elastic body 20 and the spring 30.

[0025] 4 and 5, the main body 10 is provided with an inlet channel L11, a discharge channel L12, and an overflow channel L13. As shown in FIG. 4, the inlet channel L11 connects the intake port S1 and the fuel chamber R. In this embodiment, the inlet channel L11 is formed by grooves and holes provided in the first main body 11. The inlet channel L11 guides fuel supplied from the priming pump 3 to the intake port S1 via the pipe L3 to the fuel chamber R.

[0026] 5, the discharge passage L12 connects the fuel chamber R and the discharge port S2. In this embodiment, the discharge passage L12 is formed by a groove provided in the first main body portion 11 and a hole provided in the second main body portion 12. The discharge passage L12 guides the fuel discharged from the fuel chamber R to the discharge port S2. In other words, the fuel discharged from the fuel chamber R passes through the discharge passage L12.

[0027] The overflow passage L13 connects the discharge passage L12 and the overflow outlet S3. That is, the overflow passage L13 branches off from the discharge passage L12 and is connected at one end to the discharge passage L12 and at the other end to the overflow outlet S3. In this embodiment, the overflow passage L13 is formed by a hole provided in the first main body portion 11 and a hole provided in the second main body portion 12.

[0028] In this embodiment, the overflow valve 40 is provided in the overflow passage L13 and switches between allowing and not allowing fuel to flow through the overflow passage L13. Here, the overflow valve 40 is switched between an open state, in which fuel can flow through the overflow passage L13, and a closed state, in which fuel is blocked from flowing through the overflow passage L13, depending on the pressure of fuel in the fuel chamber R.

[0029] Here, the overflow passage L13 includes a small-diameter passage portion L13a connected to the discharge passage L12 and a large-diameter passage portion L13b connected to the small-diameter passage portion L13a. The large-diameter passage portion L13b has a larger passage cross-sectional area than the small-diameter passage portion L13a. The small-diameter passage portion L13a is located closer to the discharge passage L12 than the large-diameter passage portion L13b. In this embodiment, the small-diameter passage portion L13a is provided in the first main body portion 11, and the large-diameter passage portion L13b is provided in the second main body portion 12. In this embodiment, the overflow valve 40 switches between allowing and not allowing fuel to flow through the overflow passage L13 by opening and closing an opening L13c of the small-diameter passage portion L13a at the connection portion between the small-diameter passage portion L13a and the large-diameter passage portion L13b.

[0030] More specifically, the overflow valve 40 includes a valve element 41 and a spring (valve element spring) 42. The valve element 41 is provided in the large-diameter flow path portion L13b and opens and closes the opening L13c of the small-diameter flow path portion L13a. The spring 42 is a compression spring. The spring 42 biases the valve element 41 so as to block the flow of fuel in the overflow path L13. Here, the spring 42 biases the valve element 41 so as to close the opening L13c of the small-diameter flow path portion L13a. One end of the spring 42 abuts against the valve element 41, and the other end abuts against a spring retainer 13 provided on the second main body portion 12. The spring retainer 13 is attached to the second main body portion 12 via an O-ring. Here, as an example, a male thread portion 13a is provided on the outer circumferential surface of the spring retainer 13. A female screw portion 12b is provided on the inner circumferential surface of the hole in the second main body portion 12 into which the spring retainer 13 is fitted. The spring retainer 13 is attached to the second main body portion 12 by engaging the male screw portion 13a with the female screw portion 12b of the second main body portion 12.

[0031] When the fuel pressure in the fuel chamber R reaches or exceeds a predetermined pressure, the spring 42 of the overflow valve 40 is compressed, and the valve element 41 moves away from the opening L13c of the small-diameter flow path portion L13a. This opens the opening L13c, allowing fuel to flow through the overflow path L13. Now that the overflow path L13 is open, the fuel (excess fuel) in the fuel chamber R is returned to the fuel tank 5 from the fuel pressurizing device 1 via the pipe L2.

[0032] Next, an operation of the fuel pressurizing device 1 to pressure-feed starting fuel to the engine 2 when starting the engine 2 will be described. Note that before the engine 2 is started, the solenoid valve 4 is closed. First, to start the engine 2, a user of the engine unit 100 operates (presses) the priming pump 3. As a result, fuel from the fuel tank 5 is sent to the inlet S1 of the fuel pressurizing device 1 via the pipe L4, the priming pump 3, and the pipe L3, and the fuel is sent from the inlet S1 into the fuel chamber R via the inlet passage L11.

[0033] Then, when the user operates the priming pump 3 to send fuel to the fuel pressurizing device 1, the fuel sent into the fuel chamber R pushes up the elastic body 20 against the biasing force of the spring 30 (moving the elastic body 20 in the direction in which the spring 30 is compressed), as shown in FIG. 6. This increases the volume of the fuel chamber R, and the fuel chamber R is filled with fuel. In this state, the solenoid valve 4 is closed, so the fuel in the fuel chamber R is not sent to the engine 2. In other words, the fuel pressurizing device 1 can store fuel in the fuel chamber R. The fuel stored in the fuel chamber R is biased by the spring 30 via the elastic body 20, and is in a pressurized state.

[0034] Furthermore, when the user operates the priming pump 3 to send fuel to the fuel pressurizing device 1, as shown in FIG. 7 , the fuel sent to the fuel chamber R biases the valve element 41 of the overflow valve 40 through the discharge passage L12 and the overflow passage L13 (small-diameter passage portion L13a). The spring 42 is set to begin to compress when a pressure higher than the pressure of the fuel in the fuel chamber R accumulated by the spring 30 is reached by a predetermined value. That is, the spring 42 begins to compress after the spring 30 has compressed. The valve element 41 is biased by the fuel and compressed, so that the valve element 41 moves away from the opening L13c of the small-diameter passage portion L13a. This opens the opening L13c, allowing fuel to flow through the overflow passage L13. In this state, fuel is returned from the overflow passage L13 to the fuel tank 5 via the overflow outlet S3 and the pipe L2. That is, excess fuel in the fuel chamber R is returned to the fuel tank 5 via the overflow passage L13, and the fuel in the fuel chamber R can be maintained at a predetermined pressure.

[0035] After fuel is stored in the fuel chamber R, the user starts the engine 2 by operating, for example, a recoil starter. In conjunction with this starting operation of the engine 2, the solenoid valve 4 changes from a closed state to an open state. As a result, as shown in FIG. 8, the starting fuel in the fuel chamber R, which has been pressurized by the spring 30, is forcefully sent (pressurized) all at once to the engine 2 via the discharge passage L12 and the pipe L1. In this way, the starting fuel is supplied all at once when the engine 2 is started, improving the startability of the engine 2.

[0036] As described above, in fuel pressurizing device 1, elastic body 20 is biased by spring 30, so that fuel supplied by priming pump 3 is pressurized within fuel chamber R. Since the fuel needs to be pressurized, solenoid valve 4 provided in engine unit 100 is closed while fuel is being supplied into fuel chamber R by priming pump 3. In this state, when solenoid valve 4 provided in engine unit 100 is opened to start engine 2, the pressurized fuel is forcefully supplied to engine 2 all at once. In this way, fuel pressurizing device 1 can pressure-feed the fuel required for starting to engine 2, thereby improving the startability of engine 2.

[0037] The fuel chamber R is configured to include an elastically deformable elastic body 20 in its part. In this case, the fuel pressurizing device 1 can easily change the volume of the fuel chamber R by using the elastic body 20.

[0038] The fuel pressurizing device 1 includes an overflow passage L13 branching off from the discharge passage L12, and an overflow valve 40 that switches between allowing and not allowing fuel to flow through the overflow passage L13. In this case, the fuel pressurizing device 1 can discharge excess fuel supplied into the fuel chamber R by the priming pump 3 via the overflow valve 40 and the overflow passage L13.

[0039] Overflow valve 40 includes a valve element 41 and a spring 42 that biases valve element 41. In this case, fuel pressurizing device 1 can set the volume of fuel chamber R to a desired volume by adjusting the balance of the biasing forces of spring 30 that biases elastic body 20 and spring 42 of overflow valve 40. In other words, fuel pressurizing device 1 can easily set the volume of fuel chamber R to a desired volume simply by changing the balance of the biasing forces of springs 30 and 42, without making any changes to second main body portion 12 (recess 12a) and elastic body 20. This makes fuel pressurizing device 1 easy to apply to engines 2 even if the amount of startup fuel to be pumped varies depending on the type of engine 2, etc.

[0040] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the pump that sends fuel to the fuel chamber R is not limited to the priming pump 3. Any other type of pump may be used instead of the priming pump 3 as long as it can send fuel to the fuel chamber R of the fuel pressurizing device 1. Furthermore, the solenoid valve 4 is not limited to an electromagnetic valve, and any other type of valve may be used. [Explanation of symbols]

[0041] 1...fuel pressurization device, 2...engine, 3...priming pump (pump), 4...solenoid valve (valve), 12...second main body portion (fuel chamber forming portion), 20...elastic body (fuel chamber forming portion), 30...spring, 40...overflow valve, 41...valve body, 42...spring (valve body spring), 100...engine unit, L12...discharge path, L13...overflow path, R...fuel chamber.

Claims

1. A fuel pressurizing device (1) is provided in an engine unit (100) including a pump (3), a valve (4), and an engine (2), and pressure-feeds starting fuel supplied from the pump (3) to the engine (2) via the valve (4), a first main body portion (11) having a discharge port (S2); a fuel chamber forming portion (12, 20) provided with a fuel chamber (R) to which the fuel is supplied from the pump (3) and whose volume is variable; a spring (30) that biases the fuel chamber forming portion (12, 20) so as to reduce the volume of the fuel chamber (R); The fuel chamber forming portion (12, 20) a second body portion (12) having a recess (12a) connected to the discharge port (S2) of the first body portion (11); an elastic body (20) disposed between the first body portion (11) and the second body portion (12) so as to cover the recess (12a), and forming the fuel chamber (R) together with the recess (12a), The volume of the fuel chamber (R) changes as the elastic body (20) deforms, The spring (30) is disposed in the first body portion (11) and biases the elastic body (20).

2. An overflow passage (L13) branching from the discharge passage (L12) is connected to the discharge passage (L12) through which the fuel sent out from the fuel chamber (R) passes, The fuel pressurizing device (1) according to claim 1, further comprising an overflow valve (40) that switches between allowing and not allowing the fuel to flow through the overflow passage (L13).

3. 3. The fuel pressurizing device according to claim 2, wherein the overflow valve includes a valve body and a valve body spring that biases the valve body so as to block the flow of fuel through the overflow passage.

4. A fuel pressurizing device (1) as described in claim 3, wherein the valve body spring (42) is set to begin to compress after the spring (30) has compressed.

5. The overflow flow path (L13) includes a small diameter flow path portion (L13a) and a large diameter flow path portion (L13b) connected to the small diameter flow path portion (L13a), the small diameter flow path portion (L13a) is located closer to the discharge path (L12) than the large diameter flow path portion (L13b); The valve body (41) and the valve body spring (42) are disposed in the large-diameter flow path portion (L13b), 5. The fuel pressurizing device (1) according to claim 3 or 4, wherein the valve body spring (42) biases the valve body (41) so that the opening (L13c) of the small diameter flow path portion (L13a) is closed by the valve body (41).

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