JPH0122934Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a diaphragm fuel pump for supplying fuel to the carburetor of an internal combustion engine equipped with a supercharger such as an exhaust turbo supercharger. It is something.

[Problems with conventional technology]

In an internal combustion engine with a supercharger, when the carburetor is installed downstream of the supercharger, supercharging pressure acts on the float chamber of the carburetor, so the fuel pump that supplies fuel to this float chamber is , the discharge pressure needs to be higher than that of a fuel pump in an ordinary internal combustion engine without a supercharger. in this case,
In a diaphragm fuel pump, which is generally used as a fuel pump for internal combustion engines, the rear chamber at the back of the diaphragm is open to the atmosphere. The pressure resistance of the diaphragm must be improved by increasing the thickness of the diaphragm or by strengthening the spring that supports the diaphragm, but doing so not only increases the loss of mechanical power to move the diaphragm, but also increases the loss of mechanical power needed to move the diaphragm. , the force acting on the mechanism for moving the diaphragm increases, and the durability of that part decreases.

Therefore, Japanese Utility Model Application Publication No. 56-113166 as a prior art discloses that in a diaphragm type fuel pump used for an internal combustion engine with a supercharger, the interior of the back chamber of the diaphragm is covered with a pull rod connected to the diaphragm of the fuel pump. It is proposed that the discharge pressure of the fuel pump be increased by sealing the fuel pump with a fitted bellows and introducing supercharging pressure from a supercharger into the sealed rear chamber.

However, if the rear chamber of the diaphragm is sealed with a bellows fitted over the pull rod as in this prior art, the structure of the fuel pump becomes complicated and becomes quite expensive. Since the fuel pump in this prior art has a special structure with bellows as described above, it can be used as a fuel pump that is commonly used in an ordinary internal combustion engine without a supercharger.ゝIt is not possible to use it, and a dedicated fuel pump must be manufactured.
This would lead to a significant increase in prices.

Moreover, in the prior art, the lower end of the pull rod connected to the diaphragm is engaged with one end of the bell crank lever, and the diaphragm is reciprocated by the swinging rotation of the bell crank lever. Since the pull rod oscillates in a direction perpendicular to its axis as the bell crank lever swings and rotates, another problem is that the sealing performance between the pull rod and the bellows fitted thereon is poor. Ta.

The present invention aims to solve these problems.

[Means for solving problems]

Therefore, the present invention provides a diaphragm fuel pump that is attached to a supercharged internal combustion engine and is operated by a push rod that reciprocates in the axial direction in conjunction with the rotation of the internal combustion engine. A partition plate for sealing a rear chamber of a diaphragm in the fuel pump is inserted between a mounting portion of the fuel pump and the fuel pump, and supercharging pressure from the supercharger is introduced into the rear chamber. A fitting hole through which the reciprocating push rod passes is formed in the partition plate, and an oil seal is fitted between the inner surface of the fitting hole and the outer surface of the push rod. It is configured to do this.

[Functions and effects of the idea]

In this way, by inserting a partition plate between the attachment part of the fuel pump to the internal combustion engine and the fuel pump, the rear chamber of the diaphragm in the fuel pump is sealed, and the supercharging is carried out in this rear chamber. In this case, as in the prior art, a bellows is installed in the rear chamber of the diaphragm to seal the rear chamber. Since there is no need to provide a fuel pump, it is possible to avoid a complicated structure and an expensive fuel pump, and it is possible to avoid the need for a fuel pump that is commonly used in ordinary internal combustion engines that do not have a supercharger. By simply drilling a port for boost pressure in this, it can be used as is for an internal combustion engine with a supercharger, and a significant increase in price can be avoided.

Moreover, a fitting hole is formed in the partition plate through which the reciprocating push rod passes, and an oil seal is fitted between the inner surface of the fitting hole and the outer surface of the push rod. , the axis of the push rod coincides with the sliding direction, so that the sealing performance by the oil seal is improved by the pull rod swinging in the direction perpendicular to the axis and the push rod being covered by the push rod, as in the prior art. Because the sealing performance is much higher than that with the fitted bellows,
Leakage of boost pressure can be reduced, the discharge pressure in the fuel pump can be reliably increased in proportion to boost pressure, and loss of boost pressure and, by extension, loss of output can be reduced. It has the effect of

〔Example〕

Hereinafter, the drawings in which the embodiment of the present invention is applied to a fuel pump of an internal combustion engine with an exhaust turbo supercharger will be explained. 1 and 2 respectively show an exhaust turbo supercharger in which an exhaust turbine 5 and a blower compressor 6 are directly connected, and the intake manifold 2 and the blower compressor 6 are connected to each other.
A surge tank 8 for eliminating pulsation and a carburetor 9 with a float chamber 10 are installed in the intake passage 7 connecting the
is provided with a surge tank 8 located on the upstream side, an air cleaner 11 is connected to the suction side of the blower compressor 6, and an exhaust gas is connected to the exhaust manifold 3 via an exhaust passage 12. An exhaust pipe 13 to the atmosphere is connected to the inlet side of the turbine 5 and the outlet side of the exhaust turbine 5, respectively.

Reference numeral 14 designates a conventionally known diaphragm fuel pump attached to the internal combustion engine 1 for supplying fuel in the fuel tank 15 to the float chamber 10 in the carburetor 9.
These include a push rod 16 that reciprocates in the axial direction in conjunction with a rotating part such as a crankshaft or camshaft of the internal combustion engine 1, and a bell crank lever 17 with a spring 18 that swings and rotates as the push rod 16 reciprocates. and a diaphragm 20 interlocked with the other end of the bell crank lever 17 via a pull rod 19.
and a spring 25 that supports the diaphragm 20.
It consists of an intake valve 22 for a fuel inlet 21 from the fuel tank 15 and a discharge valve 24 for a fuel outlet 23 to the float chamber 10 of the carburetor 9, and a diaphragm 20 reciprocates as the push rod 16 reciprocates. By this, the fuel tank 15
The fuel inside is sent to the float chamber 10 via a pump chamber 26.

A partition plate 28 through which the push rod 16 passes is inserted into the attachment portion of the fuel pump 14 to the internal combustion engine 1, and an oil seal 29 is fitted into the partition plate 28 at the portion where the push rod 16 passes through. While the back chamber 27 of the diaphragm 20 is sealed, the fuel pump 14 includes:
A port 31 that opens into the rear chamber 27 is provided, and the supercharging pressure in the intake passage 7 or the surge tank 8 downstream of the blower compressor 6 is transmitted to the port 31 via the supercharging pressure transmission passage 30. Configure to deploy.

With this configuration, the rear chamber 27 of the diaphragm 20 in the fuel pump 14 is sealed,
Since supercharging pressure acts on this, the fuel pump 1
The discharge pressure at No. 4 can be increased by the supercharging pressure.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a schematic diagram of an internal combustion engine, and FIG. 2 is a longitudinal sectional front view of a fuel pump. 1... Internal combustion engine, 4... Exhaust turbo supercharger, 5
...exhaust turbine, 6...blower compressor, 2 intake manifold, 3...exhaust manifold, 7...
...Intake passage, 8...Surge tank, 9...Carburizer, 10...Float chamber, 14...Fuel pump,
20...Diaphragm, 22...Suction valve, 24...
...Discharge valve, 26...Pump chamber, 16...Push rod, 19...Pull rod, 17...Bell crank lever, 27...Back chamber, 28...Partition plate,
29...Oil seal, 31...Port, 30...
...Supercharging pressure transmission passage.

Claims (1)

[Scope of utility model registration request] In a diaphragm fuel pump that is attached to a supercharged internal combustion engine and is operated by a push rod that reciprocates in an axial direction in conjunction with the rotation of the internal combustion engine, a mounting portion of the fuel pump to the internal combustion engine; , a partition plate for sealing a rear chamber of a diaphragm in the fuel pump is inserted between the fuel pump and a port for introducing supercharging pressure from the supercharger into the rear chamber; The partition plate is provided with a fitting hole through which the reciprocating push rod passes, and an oil seal is fitted between the inner surface of the fitting hole and the outer surface of the push rod. Fuel pump for internal combustion engines with feeder.