JP2006076420A - Vacuum force boosting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vacuum force boosting structure capable of securing favorably the brake operating easiness. <P>SOLUTION: The vacuum force boosting structure 10 comprises a vacuum boosting device 15 having communication with the suction passage 12 of an internal-combustion engine 11 through a first passage 13, a first check valve 16 installed in the first passage 13, a vacuum boosting device 15 having communication with the exhaust passage 18 of the engine 11 through a second passage 19, and a second check valve 21 installed in the second passage 19. According to this structure 10, the negative pressure chamber 25 of the boosting device 15 is held in a negative pressure condition through utilization of the negative pressure in the suction passage 12 and the negative pressure in the exhaust passage 18, and using this negative pressure state, the force applied to an operating rod 38 of the boosting device 15 is boosted and it is emitted from a push rod 42. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vacuum booster structure, and more particularly to a vacuum booster structure that boosts an input and outputs it by keeping a negative pressure chamber in a negative pressure state using negative pressure generated in an intake passage of an internal combustion engine.

Here, the negative pressure refers to a pressure from atmospheric pressure or lower to absolute pressure zero (absolute vacuum).
In addition, since the state in the space filled with gas at a pressure lower than atmospheric pressure is usually a vacuum, the boost structure that boosts the input using negative pressure is called "vacuum boost structure". explain.

2. Description of the Related Art A vacuum booster that boosts a pedaling force applied to a brake pedal is used in a brake system such as an automobile. As this vacuum booster, a device that uses a negative pressure generated when an air-fuel mixture is sucked into an engine is known (see, for example, Patent Document 1).
JP 2004-100560 A

Patent document 1 is demonstrated based on the following figure.
FIG. 8 is a diagram for explaining a conventional basic configuration.
The vacuum booster 100 communicates the intake passage 102 of the internal combustion engine 101 to the negative pressure chamber 104 via the intake negative pressure passage 103 and also connects the secondary air supply passage 105 to the negative pressure chamber 104 via the pipe 106. Communicated with

The secondary air supply passage 105 is connected to the upstream side of the exhaust gas purification catalyst 108, and an air pump 107 is provided in the secondary air supply passage 105. Secondary air is supplied to the internal combustion engine 101 by driving the air pump 107.
When the air pump 107 is driven, a negative pressure is generated in the pipe 106.

Here, when the air-fuel mixture is drawn into the combustion chamber of the internal combustion engine 101 from the intake passage 102, a negative pressure is generated in the intake passage 102.
If the negative pressure chamber 104 cannot be lowered to a predetermined negative pressure state only by setting the negative pressure chamber 104 of the vacuum booster 100 to a negative pressure state using the negative pressure in the intake passage 102, a pipe is provided. The negative pressure chamber 104 is lowered to a predetermined negative pressure state using the negative pressure 106.

By lowering the negative pressure chamber 104 to a predetermined negative pressure state, the pedaling force applied to the input shaft 109 is boosted using the negative pressure of the negative pressure chamber 104 when a brake pedal (not shown) is depressed. The boosted pedaling force is output from the output shaft 110.
The brake of the master cylinder is operated by the output shaft 110 to operate the brake.
In this way, the negative pressure generated by the air pump 107 for supplying secondary air is used to maintain the negative pressure chamber 104 of the vacuum booster 100 in a predetermined negative pressure state, thereby improving the operability of the brake. Secure.

However, there is a type in which the internal combustion engine 101 does not supply secondary air. In the case of the internal combustion engine 101 of a type that does not supply secondary air, it is necessary to keep the negative pressure chamber 104 of the vacuum booster 100 at a negative pressure using only the negative pressure in the intake passage 102.
For this reason, it may be difficult to lower the negative pressure chamber 104 of the vacuum booster 100 to a predetermined negative pressure state, and in that case, it is difficult to appropriately ensure the operability of the brake.

  It is an object of the present invention to provide a vacuum booster structure that can suitably ensure the operability of a brake even in an internal combustion engine that does not supply secondary air.

  The invention according to claim 1 has a negative pressure chamber communicating with the intake passage of the internal combustion engine, and maintains the negative pressure chamber in a negative pressure state using the negative pressure of the intake passage. In a vacuum booster structure that boosts the force applied to the input shaft using the output and outputs the boosted force from the output shaft, the negative pressure is placed in the vicinity of the exhaust port of the internal combustion engine in the exhaust passage of the internal combustion engine. The chamber is communicated through a passage, and negative pressure holding means for maintaining the negative pressure chamber in a negative pressure state using the negative pressure of the exhaust passage is provided in the passage.

Here, when the negative pressure chamber is brought into a negative pressure state using the negative pressure generated in the intake passage of the internal combustion engine, it may be difficult to keep the negative pressure chamber in a predetermined negative pressure state.
Therefore, in claim 1, the negative pressure chamber is communicated with the vicinity of the exhaust port of the internal combustion engine through the passage in the exhaust passage of the internal combustion engine. In this passage, negative pressure holding means for keeping the negative pressure chamber in a negative pressure state using the negative pressure of the exhaust passage is provided.

  As a result, when the negative pressure chamber is brought into the negative pressure state, the negative pressure in the exhaust passage is used even when the negative pressure chamber cannot be maintained in the predetermined negative pressure state only by using the negative pressure in the intake passage. Thus, the negative pressure chamber can be maintained in a predetermined negative pressure state.

    In the first aspect of the invention, the operability of the brake is preferable even in an internal combustion engine of a type that does not supply secondary air by keeping the negative pressure chamber in a predetermined negative pressure state using the negative pressure of the exhaust passage. There is an advantage that can be secured.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
In addition, although this embodiment demonstrates the example which employ | adopted the vacuum boosting structure for the brake system, the vacuum boosting structure of this Embodiment can also be applied to another apparatus (device).

FIG. 1 is a schematic view showing an example in which the vacuum booster structure according to the present invention is employed in a brake system.
The vacuum booster structure 10 communicates an intake passage 12 of the internal combustion engine 11 with a vacuum booster 15 via a first passage 13 and includes a first check valve 16 in the first passage 13. The vacuum booster 15 is communicated with the passage 18 via a second passage (passage) 19, and a second check valve (negative pressure holding means) 21 is provided in the second passage 19.

The first passage 13 communicates one end portion 13a with the downstream side 12a of the throttle valve 22 in the intake passage 12, and communicates the other end portion 13b with the negative pressure chamber 25 (see FIG. 2) of the vacuum booster 15. It is a passage.
The intake passage 13 includes an air cleaner 26 on the upstream side 12 b of the throttle valve 22.
The negative pressure chamber 25 is a space that is maintained in a state maintained at a predetermined negative pressure P1.

The first check valve 16 is a valve that opens when the relationship between the pressure P2 on the intake passage 12 (specifically, the downstream side 12a) side and the predetermined negative pressure P1 in the negative pressure chamber 25 is P2 <P1. It is.
Further, the first check valve 16 is a valve that is closed when the relationship between the pressure P2 on the intake passage 12 (downstream side 12a) side and the predetermined negative pressure P1 is P2 ≧ P1.
The first check valve 16 keeps the negative pressure chamber 25 in a predetermined negative pressure P1 state using the negative pressure on the intake passage 12 (downstream side 12a) side.

The second passage 19 is a passage in the exhaust passage 18 in which one end 19 a is communicated with a portion 18 a near the exhaust port 35 and the other end 19 b is communicated with a portion 13 c in the middle of the first passage 13.
One end portion 19 a of the second passage 19 is communicated with the exhaust passage 18, and the other end portion 12 b is communicated with a portion 13 c in the middle of the first passage 13, whereby the exhaust passage 18 is connected to the second passage 19 and the first passage 13. It communicates with the negative pressure chamber 25 of the vacuum booster 15 through a part 13d.
A muffler 24 is provided at the end 18 b of the exhaust passage 18.

In the second check valve 21, the relationship between the pressure P3 on the exhaust passage 18 (specifically, the portion 18a near the exhaust port 35) and the predetermined negative pressure P1 in the negative pressure chamber 25 is P3 <P1. It is a valve that opens sometimes.
Furthermore, the second check valve 21 is a valve that is closed when the relationship between the pressure P3 on the exhaust passage 18 (the portion 18a in the vicinity of the exhaust port 35) and the predetermined negative pressure P1 is P3 ≧ P1.
The second check valve 21 keeps the negative pressure chamber 25 in a predetermined negative pressure P1 state by using the negative pressure on the exhaust passage 18 (the part 18a in the vicinity of the exhaust port 35) side.

  The internal combustion engine 11 includes a cylinder 29 in a cylinder block 28, a spark plug 32 in a cylinder head 31, an intake valve 34 that opens and closes an intake port 33 of the cylinder head 31, and opens and closes an exhaust port 35 of the cylinder head 31. An exhaust valve 27 is provided, and a piston 37 is slidably provided in the cylinder 29.

The vacuum booster 15 has a brake lever 41 connected to an operating rod (input shaft) 38 via a connecting member 39 and is connected to a push rod (output shaft) 42 to a plunger 45 of a master cylinder 44.
An upper end portion 41 a of the brake lever 41 is rotatably attached to the vehicle body side 47 via a pin 46, and a brake pedal 48 is attached to the lower end portion 41 b of the brake lever 41.

  The master cylinder 44 includes a reservoir tank 51 that supplies brake oil (not shown), includes a front wheel brake outlet 52 and a rear wheel brake outlet 53, and includes a front wheel brake outlet 52 and a rear wheel brake. The outlet 53 communicates with a brake cylinder 55 for front and rear wheels via a pipe 54.

  According to the vacuum booster structure 10, the negative pressure P <b> 2 in the intake passage 12 (downstream side 12 a) and the negative pressure P <b> 3 in the exhaust passage 18 (portion 18 a near the exhaust port 35) are used to negatively The pressure chamber 25 is maintained in a predetermined negative pressure P1 state, and the force applied to the operating rod 38 of the vacuum booster 15 is boosted using the negative pressure P1 state, and the boosted force is applied to the vacuum booster 15 The plunger 45 of the master cylinder 44 is pressed by the push rod 42 by outputting from the push rod 42.

FIG. 2 is a view for explaining a vacuum booster structure according to the present invention.
The vacuum booster 15 includes a cylinder 58 in the apparatus main body 57, and a piston 61 is movably provided in the cylinder 58 via a diaphragm 59. The cylinder 58 is surrounded by the negative pressure chamber 25 and the atmospheric pressure by the diaphragm 59 and the piston 61. The negative pressure chamber 25 is provided with a return spring 63, the brake rod 41 is connected to the rear end 38a of the operating rod 38 via a connecting member 39, and the master cylinder 44 is connected to the tip 42a of the push rod 42. Connected to the plunger 45.

A connecting pipe 64 is formed in the cylinder 58 of the apparatus main body 57, the connecting pipe 64 is communicated with the negative pressure chamber 25, and the other end 13 b of the first passage 13 is connected to the connecting pipe 64. The negative pressure chamber 25 is communicated with the other end 13 b of the first passage 13 through the connection pipe 64.
An upper end portion 41 a of the brake lever 41 is rotatably attached to the vehicle body side 47 via a pin 46, and a brake pedal 48 is attached to the lower end portion 41 b of the brake lever 41.

When the pedal force is not applied to the brake pedal 48, the negative pressure chamber 25 and the atmospheric pressure chamber 62 are communicated, and the negative pressure chamber 25 and the atmospheric pressure chamber 62 are maintained at the negative pressure P1.
Therefore, the piston 61 is positioned on the end side 62 a of the atmospheric pressure chamber 62 by the spring force of the return spring 63.

In this state, when a depression force is applied to the brake pedal 48, the communication between the negative pressure chamber 25 and the atmospheric pressure chamber 62 is blocked, and the atmosphere flows into the atmospheric pressure chamber 62.
A pressure difference is generated between the negative pressure chamber 25 and the atmospheric pressure chamber 62, and the piston 61 moves to the end side 25 a of the negative pressure chamber 25 against the spring force of the return spring 63.

As the piston 61 moves, the push rod 42 moves toward the master cylinder 44, and the push rod 42 presses the plunger 45 of the master cylinder 44.
As a result, the force acting on the operating rod 38 is boosted, and the boosted force is output from the push rod 42.

By pressing the plunger 45 of the master cylinder 44 with the push rod 42, the brake oil in the master cylinder 44 is pressed with the plunger 45.
This pressing force is transmitted to the front and rear wheel brake cylinders 55 via the brake oil, and the front and rear wheel brakes are operated.

Next, the operation of the vacuum boost structure will be described with reference to FIGS.
FIG. 3 is a view for explaining an example in which the negative pressure chamber of the vacuum booster structure according to the present invention is made negative using an intake passage.
The throttle valve 22 is opened, and the intake valve 34 is opened to open the intake port 33. Further, the exhaust valve 27 is closed to keep the exhaust port 35 closed.
In this state, the piston 37 is lowered from the top dead center H1 as indicated by an arrow a.

An air-fuel mixture (not shown) in the intake passage 12 (downstream side 12a) is taken into the combustion chamber 66 as indicated by an arrow b. The pressure P2 in the intake passage 12 (downstream side 12a) becomes lower than a predetermined negative pressure P1 in the negative pressure chamber 25, that is, the relationship of P2 <P1 is established and the first check valve 16 is opened.
The gas in the negative pressure chamber 25 (see also FIG. 2) of the vacuum booster 15 is sucked into the intake passage 12 (downstream side 12a) as shown by the arrow c through the first passage 13, and the negative pressure chamber 25 is filled in the negative pressure chamber 25. Negative pressure P4 state is reached.

In this state, it can be considered that the negative pressure chamber 25 is lowered to the predetermined negative pressure P1, but in the present embodiment, the negative pressure chamber 25 is described as being lowered to the negative pressure P4.
The relationship between the negative pressure P4 and the predetermined negative pressure P1 is P4> P1.

4 (a) and 4 (b) are diagrams illustrating an example in which the negative pressure chamber of the vacuum booster structure according to the present invention is maintained in a negative pressure state.
In (a), when the piston 37 reaches the bottom dead center H2, the intake port 33 is closed by the intake valve. Thereafter, the piston 37 is raised as shown by an arrow d.

At this time, the relationship between the pressure P2 on the intake passage 12 (downstream side 12a) side and the negative pressure P4 in the negative pressure chamber 25 (see FIGS. 2 and 3) is P2> P4.
The relationship between the pressure P3 on the exhaust passage 18 (the part 18a in the vicinity of the exhaust port 35) and the negative pressure P4 in the negative pressure chamber 25 is P3> P4.
Therefore, the first and second check valves 16 and 21 are kept closed, and the negative pressure chamber 25 (see FIGS. 2 and 3) is held at the negative pressure P4.

  In (b), the air-fuel mixture is ignited by the spark plug 32 immediately before the piston 37 reaches the top dead center H1. The air-fuel mixture burns and the burned gas (combustion gas) pushes down the piston 37 as shown by an arrow e.

At this time, the relationship between the pressure P2 on the intake passage 12 (downstream side 12a) side and the negative pressure P4 in the negative pressure chamber 25 (see FIGS. 2 and 3) is P2> P4.
The relationship between the pressure P3 on the exhaust passage 18 (the part 18a in the vicinity of the exhaust port 35) and the negative pressure P4 in the negative pressure chamber 25 is P3> P4.
Therefore, the first and second check valves 16 and 21 are kept closed, and the negative pressure chamber 25 is held at the negative pressure P4.

FIG. 5 is a diagram illustrating an example in which the negative pressure chamber of the vacuum booster structure according to the present invention is continuously maintained in a negative pressure state.
The exhaust valve 27 opens and the exhaust port 35 opens just before the piston 37 reaches the bottom dead center H2. The piston 37 rises as indicated by an arrow f, and the combustion gas is discharged through the exhaust port 35 into the exhaust passage 18 as indicated by an arrow g.

At this time, the relationship between the pressure P2 on the intake passage 12 (downstream side 12a) side and the negative pressure P4 in the negative pressure chamber 25 (see FIGS. 2 and 3) is P2> P4.
The relationship between the pressure P3 on the exhaust passage 18 (the part 18a in the vicinity of the exhaust port 35) and the negative pressure P4 in the negative pressure chamber 25 is P3> P4.
Therefore, the first and second check valves 16 and 21 are kept closed, and the negative pressure chamber 25 is kept in a negative pressure state.

FIG. 6 is a view for explaining an example in which the negative pressure chamber of the vacuum booster structure according to the present invention is made negative using the exhaust passage.
When the piston 37 reaches the top dead center H1, the exhaust valve 27 is closed and the exhaust port 35 is closed.

The combustion gas discharged from the combustion chamber 66 into the exhaust passage 18 continues to flow in the exhaust passage 18 as indicated by an arrow g with inertia.
As a result, the pressure P3 of the portion 18a in the vicinity of the exhaust port 35 in the exhaust passage 18 becomes a negative pressure state.

Here, as shown in FIG. 5, when the combustion gas is discharged from the combustion chamber 66 through the exhaust port 35 to the exhaust passage 18 as indicated by the arrow g, a venturi effect occurs in the vicinity of the outlet of the exhaust port 35, The exhaust gas flow is the fastest.
Therefore, when the exhaust valve 27 is closed and the exhaust port 35 is closed, the combustion gas discharged from the combustion chamber 66 into the exhaust passage 18 in the portion 18a in the vicinity of the exhaust port 35 passes through the exhaust passage 18 at a high flow rate. Flows as indicated by arrow g.

As a result, the pressure P3 of the portion 18a in the vicinity of the exhaust port 35 in the exhaust passage 18 becomes lower than the predetermined negative pressure P1 state of the negative pressure chamber 25.
That is, the relationship between the pressure P3 and the predetermined negative pressure P1 is P3 <P1, and the second check valve 21 is opened.

  The gas in the negative pressure chamber 25 of the vacuum booster 15 is sucked into the exhaust passage 18 (the portion 18a in the vicinity of the exhaust port 35) as indicated by an arrow h through a part 13d of the first passage 13 and the second passage 19. The inside of the negative pressure chamber 25 is lowered to a predetermined negative pressure P1.

Returning to FIG. 3, after closing the exhaust valve 27, the intake valve 34 is opened to open the intake port 33.
Hereinafter, the negative pressure chamber 25 of the vacuum booster 15 can be suitably maintained at the predetermined negative pressure P1 by sequentially repeating the steps of FIGS.

  As described above, according to the vacuum booster structure 10, the negative pressure chamber 25 communicates with the portion 18 a in the vicinity of the exhaust port 35 of the internal combustion engine 11 through the second passage 19 in the exhaust passage 18 of the internal combustion engine 11. did. The second passage 19 is provided with a second check valve 21 that keeps the negative pressure chamber 25 at a predetermined negative pressure P1 using the negative pressure of the exhaust passage 18.

  Therefore, when the negative pressure chamber 25 is brought into a negative pressure state using the negative pressure P2 generated in the intake passage 12 of the internal combustion engine 11, the negative pressure chamber 25 cannot be maintained at a predetermined negative pressure P1. However, the negative pressure chamber 27 can be maintained in a predetermined negative pressure P1 state by using the negative pressure P3 generated in the exhaust passage 18.

FIG. 7 is a view for explaining an operation example of the brake system employing the vacuum booster structure according to the present invention.
When the pedaling force F is not applied to the brake pedal 48, the piston 61 is positioned on the end side 62a of the atmospheric pressure chamber 62 by the spring force of the return spring 63 shown in FIG.
In this state, when the brake pedal 48 is depressed with the depression force F, the brake lever 41 swings as indicated by the arrow i with the pin 46 as an axis. As the brake lever 41 swings, the operating rod 38 is moved as shown by an arrow j.

When the operating rod 38 moves, the communication between the negative pressure chamber 25 and the atmospheric pressure chamber 62 is blocked, and the atmosphere flows into the atmospheric pressure chamber 62.
A pressure difference is generated between the negative pressure chamber 25 and the atmospheric pressure chamber 62, and the piston 61 moves to the end side 25a of the negative pressure chamber 25 against the spring force of the return spring 63 shown in FIG.

As the piston 61 moves, the push rod 42 moves toward the master cylinder 44, and the push rod 42 pushes the plunger 45 of the master cylinder 44 as shown by the arrow l (the lowercase letter of the letter “El”).
As a result, the force acting on the operating rod 38 from the brake pedal 48 is boosted, and the boosted force is output from the push rod 42.

By pressing the plunger 45 of the master cylinder 44 with the push rod 42, the brake oil in the master cylinder 44 is pressed with the plunger 45.
This pressing force is transmitted to the front and rear wheel brake cylinders 55 via the brake oil, and the front and rear wheel brakes are operated.

  In the above-described embodiment, the example in which the vacuum booster structure 10 is employed in the brake system has been described. However, the present invention is not limited to this, and the vacuum booster structure 10 may be employed as a booster for other devices. Similar effects can be obtained.

In the above-described embodiment, an example in which the second check valve 21 is used as the negative pressure holding means has been described. However, the negative pressure holding means is not limited to this, and an electromagnetic valve or the like is used as another example. Is also possible.
The negative pressure holding means such as an electromagnetic valve detects the negative pressure in the portion 18a in the vicinity of the exhaust port 35 with a sensor, detects the negative pressure in the negative pressure chamber 25 with the sensor, and negative pressure in the portion 18a in the vicinity of the exhaust port 35. The relationship between the pressure P3 and the predetermined negative pressure P1 in the negative pressure chamber 25 is configured to open when P3 <P1.

  The present invention is suitable for application to a vacuum booster structure in which an input is boosted and output by maintaining a negative pressure chamber in a negative pressure state using negative pressure generated in an intake passage of an internal combustion engine.

It is the schematic which shows the example which employ | adopted the vacuum boost structure which concerns on this invention for the brake system. It is a figure explaining the vacuum boosting structure which concerns on this invention. It is a figure explaining the example which makes a negative pressure chamber of the vacuum booster structure which concerns on this invention a negative pressure using an intake passage. It is a figure explaining the example which keeps the negative pressure chamber of the vacuum booster structure which concerns on this invention in a negative pressure state. It is a figure explaining the example which keeps the negative pressure chamber of the vacuum booster structure concerning this invention in a negative pressure state continuously. It is a figure explaining the example which makes a negative pressure chamber of the vacuum booster structure which concerns on this invention a negative pressure using an exhaust passage. It is a figure explaining the operation example of the brake system which employ | adopted the vacuum booster structure which concerns on this invention. It is a figure explaining the conventional basic composition.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Vacuum boost structure, 11 ... Internal combustion engine, 12 ... Exhaust passage, 13 ... First passage, 15 ... Vacuum booster, 16 ... First check valve, 18 ... Exhaust passage, 19 ... Second passage (passage) , 21 ... second check valve (negative pressure holding means), 25 ... negative pressure chamber, 35 ... exhaust port, 38 ... operating rod (input shaft), 42 ... push rod (output shaft).

Claims (1)

There is a negative pressure chamber communicating with the intake passage of the internal combustion engine, the negative pressure chamber is kept in a negative pressure state using the negative pressure of the intake passage, and the negative pressure state is applied to the input shaft. In the vacuum booster structure that boosts the force and outputs the boosted force from the output shaft,
Of the exhaust passage of the internal combustion engine, the negative pressure chamber communicates with the vicinity of the exhaust port of the internal combustion engine via the passage.
A vacuum booster structure characterized in that a negative pressure holding means for maintaining the negative pressure chamber in a negative pressure state by using the negative pressure of the exhaust passage is provided in the passage.

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