JPH0335861Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to a braking device for an internal combustion engine.

[Conventional technology]

Conventionally, in diesel engines installed in large vehicles such as trucks and buses, and ships, a butterfly valve is installed in the exhaust passage as a braking device for the engine, and by operating the butterfly valve, the gas discharge action of the passage is controlled. Items that increase engine pump loss
2929 Publication), and one that brakes the engine by releasing gas from the combustion chamber of a cylinder whose engine stroke phase is near compression top dead center to dissipate the energy stored in the form of pressure (Japanese Unexamined Patent Publication No. 51 -Described in Publication No. 132343), etc.

[Problem that the invention seeks to solve]

However, since these braking devices were used alone, the maximum braking force was insufficient and safety could not be ensured sufficiently, or the ride quality, strain on the engine bearings, and engine stalling occurred at low engine speeds. No effective consideration was given to easily obtaining an appropriate braking force while taking preventive measures into account.

[Means for solving problems]

The present invention has been proposed in view of the above, and includes a single exhaust passage that collects and discharges exhaust gas flowing out from an exhaust manifold of an internal combustion engine, and a gas discharge function of the exhaust passage provided in the exhaust passage. A first solenoid valve device is formed of a butterfly valve that brakes the engine by controlling the engine, a pneumatic cylinder that operates the butterfly valve, and a first solenoid valve device that opens and closes communication between the pneumatic cylinder and the air tank. Braking means 1 is provided in each combustion chamber of the internal combustion engine, and brakes the engine by releasing gas from the combustion chamber of the engine whose stroke phase is near the top dead center of the compression stroke, and is located upstream of the butterfly valve. a second braking means formed of a third valve provided in the third valve, an oil chamber for operating the third valve, and a second solenoid valve device for opening and closing communication between the oil chamber and the oil supply source; a manual changeover switch that operates the first solenoid valve device and the second solenoid valve device so as to obtain an operating mode in which both the first braking means and the second braking means are in an actuated state; the manual changeover switch; The second solenoid valve device is interposed between the solenoid valve devices and operates according to the output of the rotation speed to detect the rotation speed of the engine, and deactivates the second braking means when the rotation speed falls below a set value. The gist of this invention is a braking device for an internal combustion engine, which is characterized by being equipped with a switch.

[Effect]

According to the present invention, an operation mode in which both the first braking means and the second braking means are in the operating state is obtained by the action of the first action control means, and also by the action of the second action control means. The second braking means is inoperative when the engine is running at low speeds, and only the first braking means, which is less likely to cause a stall even if operated at low engine speeds, is operable.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 2 denotes one braking means provided in the exhaust system of a four-cylinder compression ignition internal combustion engine for automobiles;
Reference numeral 4 indicates a total of four braking means provided in each combustion chamber of the engine, and among these, the braking means 2 as the first braking means is provided in the engine body (not shown) in which each combustion chamber is formed. an exhaust manifold 6 communicating on one side with an exhaust port of each combustion chamber;
A butterfly valve 10 installed in the downstream exhaust passage 8 of the exhaust manifold 6, a pneumatic cylinder 12 that operates the butterfly valve 10, and a pneumatic cylinder 12.
The solenoid valve device 18, which is an input section, is composed of an air passage 16 that supplies compressed air from the air tank 14 to the air tank 14, and a first solenoid valve device 18 that is interposed in the passage 16 and controls the supply of the compressed air.
When an input electrical signal is supplied to pneumatic cylinder 1,
Compressed air is supplied to the engine 2 and the butterfly valve 10 is closed, thereby controlling the release of gas from each of the combustion chambers and applying braking to the engine.

On the other hand, the specific structure of the braking means 4 as the second braking means will be explained using FIG. In addition to the exhaust port that is not open, a third port 22 that communicates with the exhaust manifold 6 or the exhaust passage 8 on the upstream side of the butterfly valve interposed position is open,
An intake valve and an exhaust valve (not shown) are installed in the intake port and the exhaust port, respectively, and this third port 2
2 is provided with a third valve 24. The intake valve and the exhaust valve are each urged in the closing direction by a valve spring (not shown) to become a normally closed valve, and the third valve 24
The valve spring 26 also biases the valve in the closing direction, making it a normally closed valve. A piston portion 28 is formed at the upper end of the third valve 24, and the piston portion 28 is fitted into a cylinder portion 32 formed on a fixing member 30 that supports an intake/exhaust valve rocker shaft (not shown). The oil chamber 34 formed by the piston section 28 and the cylinder section 32 is connected to an oil chamber 42 in a cylinder member 40 disposed on the side of the exhaust cam 38 that opens the exhaust valve through an oil passage 36. It's communicating. This oil chamber 42 is connected to the cylinder member 40
and a piston member 44 fitted into the same member 40
and the head 4 of the piston member 44.
6 is constantly brought into contact with the exhaust cam 38 by the biasing force of a spring 48. The oil passage 36 also communicates with a low-pressure oil supply source (not shown) via a second solenoid valve device 50 and an oil passage 52. In FIG. 2, 54 and 56 are a push rod and a tappet, respectively, which constitute the valve operating system of the exhaust valve.

When an input electrical signal is supplied to the solenoid valve device 50, which is an input section, the braking means 4 operates as follows.
The communication between the oil passage 52 and the oil passage 36 is cut off by the solenoid valve device 50, the oil pressure in the oil passage 36 is maintained, and the third valve 24 is opened near the top dead center of the compression stroke according to the lift of the exhaust cam 38. This causes the pressure energy of the compressed air in each combustion chamber 20 to be released, thereby applying braking to the engine.

By the way, the solenoid valve devices 18 and 50, which are the input parts of the two types of braking means 2 and 4, are connected to the battery 6 via a manual changeover switch 58 and an accelerator pedal interlocking switch 60 provided in the driver's seat.
2, and at that time, the manual changeover switch 58
A movable contact 64 connected to the battery side and three fixed contacts 66a in contact with the movable contact 64,
It is equipped with b and c. The fixed contact 66a is an off contact, 66b is a contact connected only to the solenoid valve device 18, and 66c is a contact for both solenoid valve devices 1.
8 and 50. That is, the changeover switch 58 has a movable contact 64 and a fixed contact 66c.
The connection constitutes the first operation control means. In addition, the contact point 66c and the solenoid valve device 5
A switch 68 as second operation control means is interposed between the switch 68 and the switch 68. This switch 68 is operated in response to the output of a rotation speed detection device 70 that detects the engine rotation speed, and is turned off when the engine rotation speed is below a set value and turned on when the engine speed is above the set value.

According to the above configuration, when the driver turns off the manual changeover switch 58, that is, when the movable contact 64 and the fixed contact 66a are in the connected state, the input electric signal is supplied to each solenoid valve 18, 50. First, each control means 2, 4 is in a non-operating state.

On the other hand, when the driver takes his foot off the accelerator pedal and turns on the manual changeover switch 58 in the weak state,
That is, when the movable contact 64 and the fixed contact 66b are in a connected state, an input electric signal is supplied to the solenoid valve device 18, and the braking means 2 starts operating. That is, the engine is forced to brake due to increased pumping losses. On the other hand, when the engine is being operated at a rotation speed higher than the set value and the driver has taken his or her foot off the accelerator pedal, the manual changeover switch 58
When turned on in a strong state, that is, when the movable contact 64 and the fixed contact 66c are connected, the switch 68 is closed and both solenoid valve devices 1 are closed.
An input electrical signal is supplied to 8, 50, and both braking means 2, 4 start operating. That is, the engine is subjected to a large braking force as the pressure energy in each combustion chamber is removed by the braking means 4 and the pump loss is increased by the braking means 2, and after a certain period of time, the engine speed reaches the above set value. When the lower part reaches this state, the switch 68 is released and the braking means 4 is released.
is inoperative, and braking force is received only from the braking means 2. By the way, when both the braking means 2 and 4 are operating, high-pressure gas ejected from the combustion chamber whose stroke phase is near the top dead center of the compression stroke toward the exhaust manifold 6 due to the action of the braking means 4 flows through the butterfly valve 10. A pressure wave is generated in a type of accumulator consisting of the upstream exhaust passage 8, the exhaust manifold 6, each exhaust port, and each port 22, and a part of this high-pressure gas is caused by the stroke phase being at the bottom of the intake stroke. Gas flows into another combustion chamber near the point where the internal pressure is relatively low by pushing open the blocked exhaust valve or third valve of the same combustion chamber, increasing the pressure inside the combustion chamber and filling the same chamber with gas. It acts to increase the amount. Then, when this combustion chamber enters the compression stroke and the gas in the chamber is compressed, the amount of work increases, that is, when the stroke phase of the combustion chamber is at the top dead center of the compression stroke, the amount of work is stored in the combustion chamber. Since the pressure energy increases and is dissipated by opening the third valve 22 provided in the combustion chamber, the braking force applied to the engine becomes extremely high. Therefore, when a normal braking force is required while the vehicle is running, the movable contact 64 of the manual changeover switch 58 is switched to the fixed contact 6.
By connecting the movable contact 64 to the fixed contact 66c, the desired braking force can be obtained.On the other hand, when a large braking force is required during high-speed driving, sufficient braking force can be obtained by connecting the movable contact 64 to the fixed contact 66c. Moreover, when the engine speed decreases and a large braking force is no longer required, one of the braking means 4 is deactivated and the braking force is weakened, thereby improving the riding comfort. In addition, there is less load on the engine bearings at low speeds, a sufficient lubricating oil film is maintained, the durability of the engine is improved, and stall prevention is also achieved.

In the above embodiment, the movable contact 64 is the fixed contact 66.
When the movable contact 64 is connected to the fixed contact 66c, only the braking means 2 is operated, and when the movable contact 64 is connected to the fixed contact 66c, both the braking means 2 and 4 are operated. Alternatively, when the movable contact 64 is connected to the fixed contact 66b, only the braking means 4 is activated, and when the movable contact 64 is connected to the fixed contact 66c, both the braking means 2 and 4 are activated. It is something. Note that in FIG. 3, the same reference numerals as in FIG. 1 refer to the same or substantially the same parts as those explained in FIG. 1.

Further, in the above embodiment, the manual changeover switch 58 having the fixed contacts 66b is provided, but the manual changeover switch may have only fixed contacts 66a and 66c.

Further, in the above embodiment, a total of four mechanisms for releasing pressure energy from four combustion chambers were collectively used as the braking means 4, but these mechanisms may be divided and each may be used as one braking means. be.

[Effect of idea]

According to the present invention, by obtaining an operating mode in which both the first braking means and the second braking means are activated, a large braking force is secured and the safety of vehicles equipped with the engine is ensured. At the same time, the second braking means, which tends to cause a stall if operated at low engine speeds, is deactivated at low engine speeds, and only the first braking means can be activated at low engine speeds. When braking is required during rotation, the engine is appropriately braked by the braking force of the first braking means without causing problems such as stalling.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing a first embodiment of the present invention, FIG. 2 is an enlarged sectional view of a portion of FIG. 1, and FIG. 3 is a schematic explanatory diagram showing a second embodiment of the present invention. 2, 4... Braking means, 10... Butterfly valve,
18... Solenoid valve device, 24... Third valve, 5
0... Solenoid valve device, 58... Manual changeover switch, 68... Switch, 70... Rotation speed detection device.

Claims (1)

[Scope of utility model registration request] One exhaust passage that collects and discharges exhaust gas flowing out from the exhaust manifold of an internal combustion engine, and one butterfly valve that is provided in the exhaust passage and brakes the engine by controlling the gas discharge action of the exhaust passage. and a first braking means formed of a pneumatic cylinder that operates the butterfly valve and a first solenoid valve device that opens and closes communication between the pneumatic cylinder and the air tank, and a first braking means provided in each combustion chamber of the internal combustion engine. The engine is braked by releasing gas from the combustion chamber of the engine whose stroke phase is near the top dead center of the compression stroke, and a third valve provided upstream of the butterfly valve and the third valve are operated. A second solenoid valve device formed of an oil chamber and a second solenoid valve device that opens and closes communication between the oil chamber and the oil supply source.
The first solenoid valve device and the second solenoid valve device
a manual changeover switch that operates a solenoid valve device, the manual changeover switch is interposed between the manual changeover switch and the second solenoid valve device, and is operated in response to the output of the rotational speed to detect the rotational speed of the engine; A braking device for an internal combustion engine, comprising a switch that deactivates the second braking means when the braking means falls below a set value.