JPS6034523Y2 - Air-fuel mixture intrusion prevention device for brake booster - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air-fuel mixture intrusion prevention device for a brake booster that utilizes suction negative pressure of an internal combustion engine.

As a brake booster as mentioned above, the Utility Model Application No. 52-6
872 (Utility Model Publication No. 57-5241) is known, and generally the negative pressure passage opening into the suction pipe is communicated with the power cylinder of the brake booster via a check valve. The negative pressure passage has a relatively small diameter and forms a closed circuit with one end open and the other end closed.

Therefore, the pulsation of the air-fuel mixture in the suction pipe acts on the negative pressure passage, and the air-fuel mixture is guided into this passage, passes through the check valve, enters the power cylinder of the brake booster, and boosts the brake booster. Since the device uses many rubber parts such as diaphragms, the fuel in the air-fuel mixture adheres to these parts, causing them to swell and deteriorate.

In addition, in cold weather, the water in the mixture freezes, trapping fuel in the negative pressure passage, causing check valve leakage, and making it easier for fuel to be guided into the brake booster. The problem is that it interferes with functionality.

In order to solve this problem, a canister using activated carbon or the like is installed in the negative pressure passage to adsorb the fuel in the mixture, or a negative pressure It is known that the negative pressure outlet of the suction pipe that communicates with the passage is provided with a protrusion that protrudes from the inner surface of the suction pipe, but the former has a complicated structure and also causes problems in the brake booster due to pulsation of the air-fuel mixture. could not reliably prevent intrusion.

The present invention was developed in view of the above-mentioned circumstances, and it reduces pulsation in the negative pressure passage of the brake booster, prevents the mixture from entering the negative pressure passage, and prevents the fuel in the mixture from entering the negative pressure passage. The purpose of this invention is to improve the durability of the rubber parts of the brake booster by solving the above-mentioned problems caused by water and moisture.

In other words, the air-fuel mixture intrusion prevention device for a brake booster according to the present invention, in order to achieve the above-mentioned purpose, is a brake booster that utilizes the suction negative pressure of an internal combustion engine. A negative pressure passage that is open and communicates with the power cylinder of the brake booster through a check valve is communicated with the atmosphere through an orifice at a position between the opening and the check valve. be.

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings.

In the figure, reference numeral 1 is an air cleaner, 2 is a carburetor, and 3 is an intake pipe, which constitute an intake system of an internal combustion engine 4.

Reference numeral 5 denotes a brake booster, which will be described later, and the suction pipe 3 is connected to a chamber 8 partitioned by a diaphragm 7 in the power cylinder 6.
A relatively small-diameter negative pressure passage 9 that opens to is communicated with the negative pressure passage 9, and a check valve 10 is provided in this negative pressure passage 9.

This check valve 10 is for maintaining negative pressure within the chamber 8 of the power cylinder 6.

Note that the brake booster 5 includes the diaphragm 7 and the power piston 11 provided in the power cylinder 6,
The power piston 11 is supported by a return spring 12, and is integrally provided with a bushing rod 14 for actuating the piston 13a of the mask cylinder 13, and is further operated by an operating rod 15 connected to a brake pedal (not shown). It has become.

One chamber 8 in the power cylinder 6 and another chamber 18 partitioned by the diaphragm 7 are communicated with the negative chamber 8 via a normally open vacuum valve 16, and are connected to the atmosphere side via a normally closed atmosphere valve 17. It is now possible to communicate.

Then, by depressing the brake pedal, the operating rod 15
When the vacuum valve 16 is closed and communication with one chamber 8 is cut off, the atmospheric valve 17 in the other chamber 18 is opened and the negative pressure decreases, creating a pressure difference between the two chambers 8 and 18, and the small pedal The power piston 11 is moved against the return spring 12 by the pressure of the foot, and the piston 13a of the mask cylinder 13 is pushed through the bushing rod 14, generating high hydraulic pressure to operate the brake. cylinder 13
The reaction force due to the hydraulic pressure acts on the power piston 11 and closes both the vacuum valve 16 and the atmospheric valve 17, and the pedal depression force and reaction force are in balance. When the pedal is further released, the mask cylinder 13 is closed. Hydraulic reaction force and return spring 12
Due to the restoring force, each member returns to its pre-operation state, such as opening the vacuum valve 16 and closing the atmospheric valve 17.

The configuration and operation of the brake booster 5 described above are conventionally known.

A portion 9a of the negative pressure passage 9 between the opening 19 to the suction pipe 3 and the check valve 10 is connected to the upstream side of the throttle valve 21 of the carburetor 2 and the downstream side of the Wilther element 22 of the air cleaner 1 via an orifice 20. , are communicated by a conduit 23.

The air-fuel mixture intrusion prevention device configured as described above uses suction negative pressure to pass from the pipe line 23 through the orifice 20 to the negative pressure passage 9.
There is a flow of air from the portion 9a of the air to the suction pipe 3 through the opening 19, so that even if there is pulsation in the air-fuel mixture passing through the suction pipe 3, this pulsation does not directly act on the negative pressure passage 9. First, pulsation is attenuated.

It is also conceivable that the aforementioned air flow causes an air curtain to be stretched over the portion of the negative pressure passage 9 where the orifice 20 is provided, and that the mixture is pushed back by the air flow.

These actions prevent the mixture from entering the negative pressure passage 9.

As explained above, the air-fuel mixture intrusion prevention device of the brake booster according to this invention connects the opening and the check valve of the negative pressure passage opened downstream of the throttle valve of the intake system through the orifice. Although it has a simple configuration of communicating with the atmosphere, the air-fuel mixture can be prevented from entering the negative pressure passage due to the pulsation of the air-fuel mixture in the suction system, on the opening side of the check valve of this passage. By being able to reliably prevent fuel from adhering to rubber parts such as the diaphragm of the brake booster, deterioration of the parts can be prevented and their durability can be improved.

It is also caused by the moisture in the air-fuel mixture freezing in cold weather.

This has the effect of preventing interference with the normal functioning of the brake booster as described above.

Note that the diameter of the orifice may be less than or equal to ITIrIrLφ, so that it does not adversely affect the performance of the brake booster.

[Brief explanation of drawings]

The figure is a configuration explanatory diagram showing an embodiment of the present invention. 1... air cleaner, 2... carburetor,
3... Suction pipe, 4... Internal combustion engine, 5.
... Brake booster, 6 ... Power cylinder, 7 ... Diaphragm, 8, 18 ...
...Chamber, 9...Negative pressure passage, 9a...
Portion between the opening of the negative pressure passage and the check valve, 10...
・Check valve, 11...Power piston, 12...
...Return spring, 13...Master cylinder,
13a... Piston, 14... Bush rod, 15... Operating rod, 16...
...Vacuum valve, 17...Atmospheric valve, 20...
・Opening orifice, 21... Throttle valve, 2
2...Filter element, 23...
conduit.

Claims (1)

[Scope of utility model registration request] In a brake booster that utilizes suction negative pressure of an internal combustion engine, a negative pressure passage that opens downstream of a throttle valve in the intake system and communicates with a power cylinder of the brake booster via a check valve is connected to the opening. An air-fuel mixture intrusion prevention device for a brake booster, characterized in that the air-fuel mixture intrusion prevention device for a brake booster is communicated with the atmospheric pressure side through an orifice at a position between the check valve and the check valve.