JPH07111162B2 - Gas injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention uses a slow-type and main-type gas metering means to accurately measure a gas flow rate to be injected according to an intake air flow rate. The present invention relates to a pressure balance type gas injection device in an internal combustion engine.

[Problems to be Solved by Prior Art and Invention]

In a gas injection device for an internal combustion engine that uses CNG (compressed natural gas), LNG (liquefied natural gas), etc. as fuel, conventionally, a means for detecting the intake air flow rate as pressure and a gas injection amount according to the intake air flow rate A means for controlling the air pressure by means of pressure is separately provided, and the air-fuel ratio of the air-fuel mixture is controlled by adjusting the gas flow rate according to the intake air flow rate.

However, gum and carbon contained in blow-by gas that leaks into the intake pipe adhere to the gas outlet, so the area of the outlet becomes smaller over time and the amount of gas injected decreases, so that the gas is not supplied. There was a problem that the mixing ratio of the air-fuel mixture changed.

In order to improve such a problem, it is conceivable to adopt the principle of the pressure-balance type fuel injection device described in Japanese Utility Model Laid-Open No. 1-74362 and the like proposed by the present applicant.
With this, the gas injection amount can be automatically corrected, but in this fuel injection device, the practical controllable range of the air flow rate and the fuel amount is only about 8 to 10 times. On the other hand, in an internal combustion engine that requires a wide control range, such as an automobile engine, it is necessary that the ratio of the minimum value and the maximum value of the air amount and the fuel amount to be controlled in the usage range is about 60 times. To do.

Therefore, even if the above-mentioned pressure balance type injection device is used as the gas injection device, it cannot be used as a gas injection device for an internal combustion engine for automobiles and the like, which requires a wide control range.

In view of such a problem, the present invention adopts the principle of the pressure-balance type fuel injection device described in Japanese Patent Application No. 63-12254 proposed by the present applicant, and is small in size and has a wide control range. An object is to provide a balanced gas injection device.

[Means for Solving the Problems]

The gas injection device according to the present invention includes a negative pressure diaphragm for mains to which a negative pressure is applied according to the intake air flow rate of an air venturi, a gas venturi for mains capable of measuring a gas injection amount according to the intake air flow rate, A main equipped with a main fuel diaphragm to which a pressure is applied according to the flow rate of the gas flowing through the main gas venturi, and a main interlocking member provided with a valve that interlocks both diaphragms and opens and closes the gas outlet. System gas metering means, negative pressure diaphragm for slow to which negative pressure is applied according to the amount of intake air at the opening of the air valve or piston valve in the initial opening state, and suction connected to the downstream side of the main gas venturi Depending on the gas venturi for the throw that measures the gas injection amount according to the amount of air and the gas flow rate flowing through this gas venturi for the throw A slow fuel gas diaphragm to which pressure is applied, and a slow system gas metering means provided with a slow interlocking member provided with a valve that interlocks both diaphragms and opens and closes a gas outlet, and a main gas venturi. A regulator provided in the gas passage between the gas supply sources.

[Work]

In the slow zone, intake air flows through the opening of the air valve or piston valve at the initial opening position, and a negative pressure corresponding to this small amount of air is applied to the negative pressure diaphragm for the slow displacement to displace the slow interlocking member and the slow interlocking member. The fuel diaphragm moves in conjunction with each other, a small amount of gas corresponding to the measured intake air flow rate flowing through the slow gas venturi is injected from the discharge port, and both diaphragms are balanced by the pressure according to this gas flow rate. Then, when moving to the main zone, a relatively large amount of intake air flows through the air venturi due to the air valve or piston valve whose opening changes, and a negative pressure corresponding to this is applied to the main negative pressure diaphragm to cause the main interlocking member. And the fuel diaphragm for the main is interlocked, depending on the intake air flow rate measured by the gas venturi for the main. Relatively large amount of gas is injected from the discharge port, both diaphragms are balanced by the pressure corresponding to the gas flow.

〔Example〕

A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

In the figure, 1 is an intake pipe, 2 is an air venturi provided in the intake pipe 1, 3 is an opening in the air venturi 2, and pressure sensing for mains for detecting a negative pressure P ₁ according to the air flow rate of the air venturi 2 The ports 4 are provided on the downstream side of the air venturi 2, and an air valve whose initial opening (see the drawing) is set by an idle adjustment screw (not shown), and 5 are downstream of the opening 4a of the air valve 4 at the initial opening position. The negative pressure P ₂ depending on the air flow rate at the opening 4a.
Is a pressure sensing port for the slow speed, 6 is an actuator for detecting the negative pressure on the downstream side of the air valve 4 to control the opening degree of the air valve 4, and the downstream negative pressure of the air valve 4 is small in the slow zone. The initial opening is maintained. Reference numeral 7 is a slot valve provided on the downstream side of the air valve 4, and 8 is a slow system gas metering means for injecting a small amount of gas according to a small air flow rate based on the negative pressure P ₂ detected by the slow pressure sensing port 5. , 9 are main system gas metering means for injecting a relatively large amount of gas according to a relatively large air flow rate based on the negative pressure P ₁ detected by the main pressure sensing port 3.

In the slow system gas metering means 8, 10 is a negative pressure chamber to which the negative pressure P ₂ detected by the slow pressure sensing port 5 is applied, and 11 is negative pressure P ₁ detected by the main pressure sensing port 3. In the slow zone, since the air flow rate of the air venturi 2 is small, the negative pressure P ₁ is maintained at about the atmospheric pressure P ₀ . Reference numeral 12 is a slow negative pressure diaphragm for partitioning the negative pressure chamber 10 and the atmospheric pressure chamber 11, 13 is a gas cylinder, that is, a gas supply source, 14 is a gas passage through which gas is supplied from the gas cylinder 13, and a gas venturi for a main described later. It is branched into a slow gas passage 15 and a main gas passage 16 on the downstream side of, and communicates with a bleed air passage 17 via discharge ports 15a and 16a, respectively. Reference numeral 18 is a gas venturi for throw which is arranged in the gas passage 15 for throw and can measure the gas flow rate according to the flow rate of the intake air flowing through the opening 4a of the air valve 4 having the initial opening degree, and 19 is the gas venturi 18 for this throw. The upstream chamber communicating with the upstream gas passage 15 for the throw, the downstream chamber 20 communicating with the gas venturi 18 for the throw,
Reference numeral 21 is a fuel diaphragm for slowing that divides the upstream chamber 19 and the downstream chamber 20, and 22 and 23 are shafts 22a and 23 in the negative pressure chamber 10 and the downstream chamber 20, respectively.
Negative pressure diaphragm 1 that can be rotated around a and has one end for throwing
2, a lever 24 pressed against the throw fuel diaphragm 21, a valve 24a pressed between the other ends of both levers 22 and 23, which interlocks with the displacement of both diaphragms 12 and 21 and can open and close the discharge port 15a. That is formed with a rod, that is, a throw interlocking member, 25 is a partition wall that separates the downstream chamber 20 from the throw gas passage 15 facing the discharge port 15a, and 26 is a partition wall 25 that allows the rod 24 to slide. Since it is a sliding hole that is penetrated in and the object to be measured by the slow gas venturi 18 is not a liquid but a gas, the above-mentioned prior art (Actual Kaihei 1-74
Unlike Japanese Patent No. 362), accurate measurement of the gas flow rate cannot be performed unless the downstream chamber 20 and the discharge port 15a are partitioned. Therefore, the clearance between the sliding hole 26 and the rod 24 is
It is necessary to keep the airtight state as small as possible within the range that does not hinder the sliding of, and this leads to an improvement in weighing accuracy.
Further, the bleed air passage 17 is opened to the intake pipe 1 on the downstream side of the throttle valve 7, and the gas injected from the discharge port 15a is discharged from this to the manifold.

The main gas metering means 9 also has the same structure and function as the slow gas metering means 8 (similar parts are indicated by the same reference numerals with "'"), and 27 is a main pressure sensing port. The negative pressure chamber to which the negative pressure P ₁ detected in 3 is applied, and 28 is the negative pressure chamber by the main negative pressure diaphragm 12 '.
It is an atmospheric pressure chamber partitioned by 27 and to which a constant pressure upstream of the venturi, for example, atmospheric pressure P _0, is applied. 29 is a gas venturi for the main, which is arranged in the gas passage 14 on the upstream side of the gas venturi 18 for throwing and can measure the gas flow rate according to the intake air flow rate of the air venturi 2, and 31 is the upstream of the gas venturi 29 for the main. Upstream chamber communicating with the gas passage 14 on the side, 32
Is a downstream chamber which is partitioned from the upstream chamber 31 by the main fuel diaphragm 21 'and communicates with the main gas venturi 29, and 33 is connected to the gas passage 14 between the main gas venturi 29 and the gas cylinder 13 This is a regulator that controls the gas pressure on the downstream side to a constant magnitude P ₃ , and a chamber 34 into which gas flows in and out and a chamber 35 to which the atmospheric pressure P ₀ is applied are separated by a diaphragm 36. A valve 37 for adjusting the opening area of the gas inlet 34a is connected to the diaphragm 36, and a spring 38 elastically presses the valve 37 in the valve opening direction.

Then, in the main gas measuring means 9, the discharge port 16a
An amount of gas corresponding to the amount of gas injected from the main gas venturi 29 is passed to cause pressure (negative pressure) P
₄ (P ₄ ≦ P ₃ ) is generated, and this is applied to the downstream chamber 32. The gas of pressure P ₄ is applied to the upstream chamber 19 of the slow system gas metering means 8, and the amount of gas corresponding to the gas injection amount from the discharge port 15a passes through the slow gas venturi 18 to generate a pressure (negative pressure). ) P ₅ (P ₅ ≦ P ₄ ) is generated and is applied to the downstream chamber 20.

The present embodiment is configured as described above, and the operation will be described next.

In the slow zone, since the air flow rate is small, the air valve 4 is held at the initial opening position shown in the figure, and the intake air flow rate flowing through the opening 4a is detected as the negative pressure P ₂ by the slow pressure sensing port 5, and the negative pressure chamber Applied to 10.
Since the negative pressure P ₁ of the air venturi 2 is applied to the atmospheric pressure chamber 11, the slow negative pressure diaphragm 12 is displaced downward by the differential pressure (P ₁ −P ₂ ) and is pushed and rotated to the right. The rod 24 moves upward via the valve 24a, and the valve 24a opens the discharge port 15a. When pushed by the rod 24 and the lever 23 rotates right, the throwing fuel diaphragm 21 is displaced downward, and the volume of the downstream chamber 20 increases and the pressure decreases. When the valve 24a is opened, the gas is discharged from the discharge port 15a through the bleed air passage 1
When the gas is injected into 7, and the gas passes through the slow gas venturi 18, a pressure P ₅ according to the gas flow rate is generated, and this is applied to the downstream chamber 20. Therefore the pressure difference in the slow fuel diaphragm 21 and the pressure P ₄ in the upstream chamber 19 (P ₄ -
P ₅ ) is applied, and this differential pressure (P ₄ −P ₅ ) is the load in the opposite direction (upward) to the load due to the differential pressure (P ₁ −P ₂ ) applied to the negative pressure diaphragm 12 for the slow motion. Diaphragm 12,2
The opening area of the discharge port 15a and the valve 24a is determined at the position where the pressure of 1 is balanced, and the gas venturi 18
Discharge port 15a after passing through the throwing gas passage 15
The flow rate of the gas injected from is determined. This gas flow rate corresponds to the intake air flow rate, but the air-fuel ratio of the air-fuel mixture can be controlled to be constant.

In addition, the gas flow rate of the gas venturi 18 for throw and the discharge port 15a
When the former is larger than the latter, the pressure of the gas passage 15 between them becomes large, and the gas flow rate of this venturi 18 decreases to reduce the pressure.
Since P ₅ increases, the differential pressure (P ₄ -P ₅₎ differential pressure (P ₁ -P ₂₎
It becomes smaller, the valve 24a is further opened, and the gas flow rate at the discharge port 15a increases. Conversely, if the latter is larger,
Since the pressure P ₅ becomes smaller, the differential pressure (P ₄ −P ₅ ) becomes the differential pressure (P ₁ −
P ₂ ), the valve 24a moves in the closing direction, and the gas flow rate at the discharge port 15a decreases. Therefore, it can be understood that the flow rate of the slow gas venturi 18 and the flow rate of the discharge port 15a are equal in the balanced state, and the gas flow rate measured by the slow gas venturi 18 is injected from the discharge port 15a.

Next, the above-mentioned relationship in the slow zone will be described by an expression. Q _a : intake air flow rate, Q _f : gas flow rate, N ₁ : load of negative pressure diaphragm 12 for slow, N ₂ : load of fuel diaphragm 21 for slow, K _a : Flow coefficient of air venturi 2 * Area of air venturi 2, K _f : Flow coefficient of gas venturi 18 for slow * Area of gas venturi 18 for slow, A ₀ : Negative pressure for slow and fuel diaphragm 12, 21 When each effective area is A / F: air-fuel ratio, A / F = Q _a / Q _f , _{N 1 = A 0 * (P} 1 -P 2), a _{N 2 = A 0 * (P} 4 -P 5).

Now, at the position where N ₁ = N ₂ , the negative pressure for throw and the fuel diaphragms 12 and 21 are balanced, so P ₁ −P ₂ = P ₄ −P ₅ , And eventually, Becomes

Then, as the intake air flow rate increases, the negative pressure P ₂ also increases, and the differential pressure (P ₁ −P ₂ ) applied to the negative pressure diaphragm 12 increases, and the downward displacement of both diaphragms 12 and 21 and the valve The opening area of 24a also increases. Then, the gas flow rates of the discharge port 15a and the slow gas venturi 18 increase, the pressure P ₅ decreases, and the upward differential pressure (P ₄ −P ₅ ) in the slow fuel diaphragm 21 increases. A balanced state is maintained and the air-fuel ratio of the mixer is also maintained constant.

In the slow zone, since the pressure P ₁ is almost equal to the atmospheric pressure P ₀ , no gas is discharged from the main-system gas metering means 9, and the pressures P ₃ and P ₄ are maintained at substantially the same level.

Further, the gas flow rate measured by the slow gas venturi 18 is that which has been supplied through the main gas venturi 29 and the slow gas passage 15, and is measured by the main gas venturi 29 in the slow zone. Within the range of the minimum possible gas flow rate, a small amount of gas corresponding to a small amount of intake air is measured by the slow gas venturi 18 and injected.

Then, when the intake air flow rate increases and the air valve 4 starts to open and shifts to the main zone, the intake air flow rate flowing through the air venturi 2 is detected by the main pressure sensing port 3 as a negative pressure P ₁ , and the main-system gas measuring means 9 As the differential pressure (P ₀ −P ₁ ) is applied to the negative pressure diaphragm 12 ′ for the main of the main body and the downward displacement occurs, the rod 24 ′, that is, the interlocking member for the main and the main The fuel diaphragm 21 'works together. Then, the gas flow rate measured by the gas venturi 29 for the main is the discharge port 16a.
Is injected from the pressure P ₄ in accordance with the gas flow downstream chamber 32
Is introduced into the main fuel diaphragm 21 ′, and an upward differential pressure (P ₃ −P ₄ ) is applied to both main diaphragms 12 ′, 2
1'is balanced and the fuel ratio of the air-fuel mixture is kept constant.

As the negative pressure P ₁ in the air venturi 2 increases, the differential pressure (P ₁ −P ₂ ) applied to the slow negative pressure diaphragm 12 in the slow system gas metering means 8 becomes smaller, and the slow system gas metering means 8 produces a smaller pressure difference. The gas injection amount becomes small.

As described above, according to the present embodiment, in the slow zone, the slow system gas metering means 8 injects a small amount of gas according to the small amount of intake air, and in the main zone, the main system gas metering means 9 is used for comparison. Since a relatively large amount of gas is injected in response to a large amount of intake air, even if the controllable width of the air flow rate and gas flow rate by each gas metering means 8 and 9 is about 8 times, A control width of about 64 times can be secured, and it can be sufficiently used as a gas injection device for automobiles and the like. Further, according to the structure of this embodiment, the device can be downsized and the air-fuel ratio of the air-fuel mixture can be controlled with high accuracy.

Further, a regulator 33 is connected to the gas passage 14 on the upstream side of the main gas venturi 29, and the pressure on the downstream side thereof is set to the atmospheric pressure P _0.
It is so arranged to control a certain size P ₃ with respect to, be varied by the density of gas conditions supplied from the gas cylinder 13, the gas metered by the main gas venturi 29 and the slow gas venturi 18 It is possible to prevent variations in flow rate measurement.

Since the gas injected by the slow system gas metering means 8 is sent through the main gas venturi 29, it is a part of the gas measured by the main gas venturi 29 in the main zone. , Does not affect the accuracy of weighing.

Although the air valve 4 is used in this embodiment, it goes without saying that a piston valve or the like may be used instead of the air valve 4.

〔The invention's effect〕

As described above, according to the gas injection device of the present invention, the narrow-slow gas metering means of control width and the main gas metering means are combined, and the pressure of the gas to be supplied to the upstream side thereof is controlled to be constant. Since the regulator is provided, the control range of the intake air flow rate and the gas flow rate can be widened, and the size is small, the air-fuel ratio of the air-fuel mixture can be accurately controlled, and the variation in the measurement of the gas flow rate is prevented. be able to.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are schematic cross-sectional views showing an embodiment of a gas injection device according to the present invention. 2 ... Venturi, 4 ... Air valve, 8 ... Slow gas measuring means, 9 ... Main gas measuring means, 12 ... Slow negative pressure diaphragm, 12 '... Main negative pressure diaphragm, 13 ... Gas cylinder, 14 ... Gas passage, 15a, 16a
...... Discharge port, 18 …… Slow gas venturi, 21 …… Slow fuel diaphragm, 21 ′ …… Main fuel diaphragm, 24,24 ′ …… Rod, 24a, 24′a …… Valve, 3
3 …… Regulator.

Claims (1)

[Claims] 1. A gas injection device for an internal combustion engine adapted to discharge a gas in an amount corresponding to an intake air flow rate, wherein a negative pressure diaphragm for mains to which a negative pressure is applied according to an intake air flow rate of an air venturi, A gas venturi for a main, which is arranged in a gas passage to which gas is supplied from a gas supply source and can measure a gas injection amount according to an intake air flow rate, and a pressure according to a gas flow rate flowing through the gas venturi for main are provided. A main gas metering means including a main fuel diaphragm to be applied and a main interlocking member provided with a valve for interlocking both diaphragms and opening and closing a gas discharge port, and on the downstream side of the air venturi. Negative pressure diaphragm for slow to which negative pressure is applied according to the intake air flow rate at the opening of the air valve or piston valve at the initial opening position, and A gas venturi for the throw, which is connected to the downstream side of the main gas venturi and can measure the gas injection amount according to the intake air flow rate, and a pressure for the throw to which a pressure according to the gas flow rate flowing through the gas venturi for slow is applied. A slow system gas metering means including a fuel diaphragm and a slow interlocking member provided with a valve that interlocks both diaphragms and can open and close a gas outlet, and a gas passage upstream of the main gas venturi. A gas injection device, comprising: a regulator provided in the.