JP2512145Y2 - Fuel supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is directed to a fuel supply device for an internal combustion engine, and more particularly to a pressure difference between a negative pressure and an atmospheric pressure generated in an intake passage, and a fuel passage provided in the fuel passage. By supplying the fuel pressure difference between the upstream side and the downstream side of the orifice, the fuel flow rate can be measured so that the air-fuel ratio of the air-fuel mixture becomes constant. The present invention relates to a supply device.

[Problems to be solved by conventional techniques and devices]

Conventionally, in a device that measures the fuel flow rate based on the relationship between the flow rate and the pressure of the fuel flowing through the orifice, such as the fixed venturi type vaporizer and the fuel injection device in Japanese Patent Application No. 62-169266, only the fuel supplied to the engine is used. Since the pressure is proportional to the square of the flow rate as shown in FIG. 9 when it is metered by the orifice, a fuel flow rate which is, for example, 6 times the minimum supply fuel flow rate of the apparatus is If it flows, the pressure becomes 36 times, which is a practical limit, but there is a problem that the range of fuel flow rate is about 40 times the minimum supply fuel flow rate in general automobile engines. . Such a problem is also present in the fuel supply device of Japanese Patent Publication No. 49-30962, and it was difficult to measure the fuel flow rate over a wide range with one system. In order to solve such a problem, Japanese Patent Application No. 63-12254
There is also an apparatus having a configuration in which two or more systems of a slow system and a main system are arranged, such as No., but this has a problem that the structure is complicated and the connection between the slow system and the main system is not smooth. Further, in a single-system fuel supply device such as a SU vaporizer or K-JETRO, there is a problem in measurement accuracy because measurement is performed by a change in the cross-sectional area of the fuel flow passage (change in flow passage resistance) according to the air flow rate. It was

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel supply device capable of highly accurately measuring a fuel flow rate over a wide range by a single fuel system.

[Means for solving the problem]

The fuel supply device according to the present invention comprises a flow path for sending out a predetermined flow rate of fuel from a fuel supply source through a constant flow rate control means and returning a return flow rate fuel to the fuel supply source again through an orifice of the fuel control means. A flow path is provided between the constant flow rate control means and the orifice so that the discharge flow rate of fuel can be injected into the intake passage, and the pressure difference and the orifice detected by the air flow rate detection means are provided. And a fuel control means for keeping the air-fuel ratio of the air-fuel mixture constant by measuring the discharge flow rate so as to balance the fuel pressure difference between before and after.

The constant flow rate control means connects the diaphragm that separates the upstream chamber and the downstream chamber, the valve that is connected to the diaphragm and that opens the upstream chamber, and the upstream chamber and the downstream chamber that communicate with each other. It consists of an orifice.

The air flow rate detecting means includes a piston valve that constitutes a variable venturi portion, a negative pressure passage provided at a position facing the piston valve of the intake passage, and an air passage.

Each fuel control means is provided with a valve which is divided into four chambers and controls the fuel of the discharge flow rate to be injected according to the pressure difference detected by the air flow rate detection means.

Still another fuel control means is provided with a negative pressure diaphragm and a fuel diaphragm facing each other, and is provided with a valve for controlling the discharge flow rate of fuel to be injected according to the pressure difference detected by the air flow rate detection means.

As described above, the fuel supply device of the present invention injects the discharge flow rate, which is measured according to the flow rate of the air sucked into the intake passage, out of the predetermined flow rate of fuel from the fuel supply source without passing through the orifice. And the remaining return flow rate is returned to the fuel supply source via the orifice,
The relationship between the fuel discharge flow rate and the fuel pressure difference has changed from a quadratic function relationship in the prior art to a substantially linear function relationship, and has a linear shape. As a result, the fuel supply device of the present invention can realize highly accurate measurement of the discharge flow rate of fuel over a wide range even with a single fuel system, and the connection from the slow system to the main system is extremely smooth. .

[Action]

Therefore, of the fuel of a predetermined flow rate sent from the constant flow rate control means, the discharge flow rate according to the pressure difference of the air flow rate is branched and injected, and the remaining return flow rate is returned to the fuel supply source via the orifice.

Further, a constant flow rate of fuel always flows through the constant flow rate control means.

Further, the piston valve forms a variable venturi portion according to the air flow rate, and a pressure difference according to the air flow rate is detected.

Further, in each fuel control means, the discharge flow rate according to the pressure difference detected by the air flow rate detection means is measured as the difference between the predetermined flow rate and the return flow rate flowing through the orifice, and the fuel is injected.

〔Example〕

The first embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a schematic cross-sectional view of a fuel supply apparatus. 1 is an air flow rate detecting means for detecting a pressure difference according to an air flow rate, and 2 is a fuel supply source composed of a fuel pump and a tank (not shown). The constant flow rate control means 3 for controlling the delivery flow rate to be constant is a fuel control means for controlling the amount of fuel discharged to the intake passage 4 according to the air flow rate. In the air flow rate detecting means 1 shown in FIG. 2 (A), 5 is a piston valve that moves forward and backward in a direction orthogonal to the air flow direction of the intake passage 4 to form a variable venturi portion 5a, and 6 is a piston valve 5 A negative pressure is formed in the tip circular portion of the suction chamber, which produces a negative pressure according to the flow rate of air flowing through the variable venturi portion 5a.
5b is an opening through which the piston valve 5 can be operated, 7 is a spring for urging the piston valve 5 in a direction to narrow the variable venturi portion 5a, and 8 is an elastic force of the spring 7 via a seat 8a. The adjusting screw to be obtained, 9 is a dynamic pressure chamber which is provided in a stepped portion having a different diameter of the piston valve 5 and into which the atmosphere of the air horn is introduced, and 10 is opened in the variable venturi portion 5a to adjust the air flow rate of the venturi portion 5a. A negative pressure passage for detecting a corresponding negative pressure, and 11 is an air passage opened to the air horn for detecting a relatively high pressure (for example, atmospheric pressure). The variable venturi portion 5a is configured as shown in FIG. 2B so that the pressure difference (for example, the atmospheric pressure and the negative pressure) generated according to the air flow rate corresponds to the relationship between the fuel flow rate and the pressure described later. Intake passage 4 as much as possible
The opening 4a is formed. An air valve type may be used instead of the piston valve. Further, in the constant flow rate control means 2 shown in FIG. 3, 12 is an upstream chamber into which fuel is introduced from the opening 12a, and 13 is separated from the upstream chamber 12 by a diaphragm 14 so that a predetermined flow rate of fuel is sent out from the opening 13a. A downstream chamber, 15 is an orifice communicating between both chambers 12 and 13, 16 is a valve whose one end is connected to the diaphragm 14 and which is opened by a predetermined amount with respect to the opening 12a of the upstream chamber 12, 17 Is a spring that elastically presses the diaphragm 14 toward the upstream chamber 12 side, 18 is an adjusting screw that can adjust the elastic force of the spring 17 via the plate seat 18a, and adjusts the valve opening amount of the valve 16 by the adjusting screw 18. The fuel flow rate from the constant flow rate control means 2 can be adjusted. Instead of this, a constant flow rate type pump may be used as the constant flow rate control means. Further, in the fuel control means 3 shown in FIG. 1, 19 is a constant flow rate control means 2 from have fuel of a predetermined flow rate is supplied discharge flow rate Q fuel intake passage _a 4 to be described later of the fuel of the predetermined flow rate
An upstream chamber having an injection port 19a for discharging the negative pressure chamber, 20 is a negative pressure chamber which is partitioned from the upstream chamber 19 by a first diaphragm 21, and a negative pressure is introduced from the negative pressure passage 10, and 22 is a negative pressure chamber 20 by an inner wall 23. An air chamber into which the atmosphere is introduced from the air passage 11, 24 is a downstream chamber partitioned from the air chamber 22 by a second diaphragm 25, 26 is an orifice connecting the upstream chamber 19 and the downstream chamber 24, 27 Is a fuel pressure regulator that keeps the fuel pressure in the downstream chamber 24 at a predetermined level and returns the fuel that has passed through the orifice 26 to the fuel supply source; 28 is the first and second diaphragms 2 that are inserted through the small holes 23a of the inner wall 23;
A connecting rod in which 1, 25 are connected, and a valve 28a capable of opening and closing the injection port 19a is formed at the lower end portion thereof. 29 is a spring for elastically pressing the second diaphragm 25 in the direction of closing the valve 28a, and 30 is a spring 29 via the plate seat 30a.
It is an adjusting screw for adjusting the elasticity of.
Then, when the fuel injection, the difference Q _b (= Q of the variable discharge flow rate Q _a fuel flow rate i.e. the return flow through the orifice 26 is ejected from the predetermined flow rate Q and the injection port 19a fed from the constant flow rate control means 2 -Q _a ). If the fuel pressure difference before and after the orifice 26 is P, and the fuel pressure difference before and after the orifice 26 is P _o when the discharge flow rate Q _a = 0, the discharge flow rate Q _a and the differential pressure (P ₀ −P) Although the relationship depends on the set value of the predetermined flow rate Q, the relationship is close to a straight line that is slightly convex as shown in FIG.

Also, set the effective area of each diaphragm 21, 25 to S, spring 2
Assuming that the elasticity of 9 is F _sp and the pressure difference detected by the air flow rate detection means 1 is F _a , there is a relationship of P × S + F _a × S + F _sp = 0 (i), and the fuel control means 3 The function of is to balance the pressure difference in this way, and as a result, the fuel flow rate (discharge flow rate) according to the air flow rate is discharged. 5 (A) shows the relationship between the fuel pressure difference P before and after the orifice 26 and the discharge flow rate Q _a, and FIG. 5 (B) shows the air flow rate required by the air flow rate detecting means 1 and its corresponding value. It is a figure which shows the characteristic of each differential pressure.

The present embodiment has the above configuration, and the operation will be described below.

In the fuel supply system according to the present embodiment, prior to starting the engine, for example, when the engine switch is operated to start, a fuel pump (not shown) is first started, and the fuel control is performed from the fuel supply source through the constant flow rate control means 2. A predetermined flow rate Q of fuel is sent to the means 3. At this stage when the engine is not started, the pressure difference is not detected by the air flow rate detecting means 1, and the valve 28a is in the closed state. The fuel having the predetermined flow rate Q introduced into the upstream chamber 19 of the fuel control means 3 flows into the downstream chamber 24 through the orifice 26 under the differential pressure P ₀ , and further returns to the fuel supply source through the fuel pressure regulator 27. . That is, when the engine is not yet started, the load generated by the differential pressure P ₀ before and after the orifice 26 and the load of the spring 29 are balanced, the valve 28a is closed, and the fuel of the predetermined flow rate Q is The fuel pump circulates in the closed flow path formed by the fuel supply source, the constant flow rate control means 2, the fuel control means 3, the fuel pressure regulator 27 and the like.

Next, when the engine is started by the ignition operation of the engine switch, air is sucked into the intake passage 4. Then, the air flow rate increases and the air flow rate detection means 1
When a pressure difference is detected at, the negative pressure is introduced into the negative pressure chamber 20, the first diaphragm 21 is displaced to the negative pressure chamber 20 side, and the valve 28a
Is opened and the fuel discharge flow rate Q _a is injected into the intake passage 4 without passing through the orifice 26, the fuel pressure in the upstream chamber 24 is reduced, and the pressures applied to both diaphragms 21 and 25 are balanced. At the same time the fuel pressure difference P before and after the return flow Q _b through the orifice 26 is reduced from P _o, eventually the pressure difference corresponding to the air flow rate (small → large) and the fuel pressure differential across the orifice 26 (large →
The air-fuel ratio of the air-fuel mixture becomes constant when (small) and () are balanced.

In this way, the discharge flow rate Q _a and the differential pressure (P _o −P) become the fourth
Since the relationship is close to the straight line shown in the figure, it is possible to control the fuel flow rate with high accuracy over a wide range.

FIG. 6 is a schematic sectional view showing a second embodiment in which the structure of the fuel control means 31 is slightly different from that of the first embodiment, and 32 is an opening 19
A valve 28b formed at the lower end of the connecting rod 28 is a fuel passage that is connected to the upstream chamber 19 via b and is supplied with a predetermined flow rate of fuel from the constant flow rate control means 2 and flows through the orifice 26. flowing into the return flow Q _b of the upstream chamber 19 is controlled. An injection nozzle 33 is connected to the other end of the fuel passage 32 and injects the discharge flow rate Q _a into the intake passage 4, and has a built-in diaphragm 34 and a spring 35 to which a needle valve 34 a is connected.

Therefore, when the differential pressure is applied from the air flow rate detecting means 1, the valve 28b is moved in the valve closing direction, the fuel inflow amount from the fuel supply source is reduced, and the pressure in each chamber 19, 24 is reduced. Therefore, the load generated on the diaphragm 34 of the injection nozzle 33 increases and the valve 34a is opened against the elasticity of the spring 35 to inject the fuel at the discharge flow rate, so that the fuel pressure difference before and after the orifice 26 decreases and The flow rate pressure difference and the fuel pressure difference before and after the orifice 26 are balanced.

Structure first Figure 7 is a fuel control unit 36 is a schematic sectional view showing a slightly different third embodiment and the second embodiment, 28c the return flow rate caused to the opening 24a of the downstream chamber 24 on-off valve Q _b A valve for controlling the return of the fuel to the fuel supply source, 37 is another spring which is arranged to face the spring 29 through the first diaphragm 21 and elastically presses the first diaphragm 21 toward the upstream chamber 19 side, In this embodiment, both springs 29 and 37
The difference in elasticity between and corresponds to F _sp in equation (i) above.

Therefore, when the first diaphragm 21 is displaced to the negative pressure chamber 20 side due to the pressure difference detected by the air flow rate detecting means 1 and the valve opening amount of the valve 28c is reduced, the fuel pressure in the upstream chamber 19 is increased and the discharge flow rate Q _a is injected from the injection nozzle 33, and the pressure difference of the air flow rate and the fuel pressure difference before and after the orifice 26 are balanced.

FIG. 8 is a schematic sectional view showing a fourth embodiment having a structure of the fuel control means 38 different from the above-mentioned embodiments,
39 is a negative pressure diaphragm that separates the negative pressure chamber 20 from the air chamber 22, 40
Is a fuel diaphragm that separates the upstream chamber 19 and the downstream chamber 24, 28d
Is a valve that is formed in the middle of a connecting rod 28 that connects the negative pressure diaphragm 39 and the fuel diaphragm 40 across the intake passage 4 and controls the opening and closing of the injection port 19a of the upstream chamber 19.

A bearing may be used to reduce the frictional force when the piston valve 5 is operating in the air flow rate detecting means.

[Effect of device]

As described above, according to the fuel supply device of the present invention, the discharge flow rate measured according to the air flow rate of the fuel of the predetermined flow rate is injected without passing through the orifice, and the remaining return flow rate is passed through the orifice. Since the fuel flow rate is returned to the fuel supply source, the relationship between the discharge flow rate and the fuel pressure difference is close to a straight line, and a single fuel system can accurately measure the fuel flow rate over a wide range. The structure is also simplified, and there is no problem with the connection between the slow system and the main system.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of a fuel supply device according to the present invention, FIG. 2 (A) is a schematic sectional view of an air flow rate detecting means, and (B) is from an arrow direction of FIG. FIG. 3 is a diagram showing the opening area of the intake passage, FIG. 3 is a schematic sectional view of the constant flow rate control means, FIG. 4 is a diagram showing the relationship between the discharge flow rate and the differential pressure in the first embodiment, and FIG. The figure which shows the relationship between the discharge flow volume in 1st Example, and the pressure difference before and behind an orifice, (B)
Is a diagram showing the required relationship between the air flow rate and the differential pressure in the first embodiment, and FIGS. 6, 7, and 8 are schematic diagrams showing the second, third, and fourth embodiments of the present invention, respectively. FIG. 9 is a sectional view showing the relationship between the fuel flow rate (discharge flow rate) and the differential pressure before and after the orifice in the conventional device. 1 ... Air flow rate detection means, 2 ... Constant flow rate control means, 3,
31,36,38 ... Fuel control means, 4 ... Intake passage, 5 ... Piston valve, 19 ... Upstream chamber, 20 ... Negative pressure chamber, 21 ... First diaphragm, 24 ... Downstream chamber, 25 ...... Second diaphragm, 26 …… Orifice, 28a, 28b, 28c, 28d …… Valve, 3
3 ... Injection nozzle, 39 ... Negative pressure diaphragm, 40 ... Fuel diaphragm.

Claims (7)

(57) [Scope of utility model registration request] 1. A flow path for returning a fuel having a predetermined flow rate from a fuel supply source via a constant flow rate control means and returning a fuel having a return flow rate to the fuel supply source via an orifice of the fuel control means, The fuel control means is provided with a flow path for branching the flow path between the orifice and the constant flow rate control means so as to inject a discharge flow amount of fuel into the intake passage, and the pressure detected by the air flow rate detection means. A fuel supply device configured to maintain a constant air-fuel ratio of an air-fuel mixture by measuring the discharge flow rate so as to balance the difference and the fuel pressure difference before and after the orifice. 2. A constant flow rate control means, a diaphragm for partitioning an upstream chamber and a downstream chamber, a valve connected to the diaphragm for opening and closing an opening of the upstream chamber, and the upstream chamber. The fuel supply device according to claim (1), wherein the utility model registration comprises an orifice that communicates with the downstream chamber and a spring that biases the diaphragm in a valve opening direction. 3. An air flow rate detecting means, wherein a piston valve capable of advancing and retracting to and from an intake passage according to an air flow rate, a spring for urging the piston valve in an advancing direction, and an inner wall of the intake passage facing the piston valve. The utility model registration claim (1) comprising a negative pressure passage that opens and an air passage that opens to the air horn. 4. A fuel control means, a first diaphragm for partitioning an upstream chamber provided with an injection port and a negative pressure chamber, a second diaphragm for partitioning a downstream chamber and an air chamber, and a connecting rod for connecting both diaphragms. A utility model registration claim including a valve for injecting fuel of a discharge flow rate according to a pressure difference detected by an air flow rate detection means, and a spring for urging the valve in a valve closing direction. The fuel supply device according to any one of (1) and (3). 5. The fuel control means includes a first diaphragm for partitioning an upstream chamber having an opening and a negative pressure chamber, a second diaphragm for partitioning a downstream chamber and an air chamber, and a connecting rod for connecting both the diaphragms. A valve that is provided and that controls the return flow rate that passes through an orifice that connects the upstream chamber and the downstream chamber in accordance with the pressure difference detected by the air flow rate detection means, and urges the valve in the valve opening direction. The utility model registration claim (1), (2) or (3), comprising: a spring; and an injection nozzle connected between the valve and the constant flow rate control means for injecting a discharge flow rate of fuel. The fuel supply device according to any one of claims. 6. The fuel control means includes a first diaphragm for partitioning the upstream chamber and the negative pressure chamber, a second diaphragm for partitioning the downstream chamber having an opening and the air chamber, and a connecting rod for connecting both the diaphragms. A valve that is provided and that controls the return flow rate that returns to the fuel supply source according to the pressure difference detected by the air flow rate detection means, a spring that urges the valve in the valve closing direction, and a valve that is connected to the upstream chamber The fuel supply device according to any one of claims (1) and (3), further comprising an injection nozzle that injects fuel at a discharge flow rate. 7. A fuel control means includes a fuel diaphragm for partitioning an upstream chamber and a downstream chamber having an injection port, a negative pressure diaphragm for partitioning a negative pressure chamber and an air chamber, and a connecting rod for connecting both diaphragms. A utility model registration claim comprising a valve which is provided and injects fuel at a discharge flow rate according to a pressure difference detected by the air flow rate detection means, and a spring which biases the valve in a valve closing direction ( The fuel supply device according to any one of 1) or (3).