JPH0544483Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an engine braking device in which an auxiliary exhaust valve is provided in the exhaust system in addition to an intake valve and an exhaust valve.

<Prior art> For freight vehicles equipped with relatively high-output diesel engines, engine braking devices that combine an exhaust braking device and a compression work absorption type braking device are known for the purpose of assisting the braking force during loading. It is being

A compression work absorption type brake system stops the supply of fuel to the combustion chamber when the driver takes his foot off the accelerator pedal while the vehicle is running, and uses the resistance during the compression process of the piston to stop the rotation of the drive wheels. This is something that is actively suppressed. For this reason, it is desirable to connect the high-pressure combustion chamber to the exhaust passage side to exhaust the intake air just before the end of the compression process.Generally, an auxiliary exhaust valve (an auxiliary exhaust valve) that connects the combustion chamber to the exhaust passage side only during engine braking is desirable. Three valves) are attached to each cylinder.

This engine braking device operates an exhaust brake during engine braking, and the auxiliary exhaust valve of the compression work absorption type braking device opens the auxiliary exhaust passage.

<Problems to be solved by the invention> In the above-mentioned engine braking device, the combustion chamber and the exhaust passage are constantly communicated with each other by the auxiliary exhaust valve during engine braking, so even when the intake valve is open, the combustion chamber and the exhaust passage are kept in communication with each other. are in a connected state. As a result, the exhaust pressure flows back into the intake system during the intake stroke, resulting in a decrease in exhaust pressure, a decrease in exhaust braking force, and a decrease in the overall absorption capacity.

The present invention has been devised to effectively solve the above-mentioned drawbacks, and aims to provide a highly reliable engine braking device by significantly increasing absorption capacity.

<Means for Solving the Problems> The configuration of the present invention to achieve the above object includes an auxiliary exhaust passage whose both ends communicate with the combustion chamber of the engine and the exhaust passage, and a mechanism for opening and closing the auxiliary exhaust passage. an auxiliary exhaust valve reciprocably provided in the auxiliary exhaust valve, an oil passage whose one end communicates with the hydraulic pressure receiver of the auxiliary exhaust valve stem portion and whose other end communicates with the hydraulic pump, and a hydraulic control provided at an intermediate portion of the oil passage. an auxiliary exhaust valve drive device including a valve; and an auxiliary exhaust valve driving device that determines the operation of engine braking based on the driving state of the vehicle, operates the hydraulic control valve during engine braking to maintain the auxiliary exhaust valve in an open state, and supplies air to the combustion chamber. an intake valve rocker arm that swings to drive the intake valve in the opening direction; The present invention is characterized by comprising an auxiliary exhaust passage closing means for closing the auxiliary exhaust passage with the auxiliary exhaust valve by communicating the oil passage with a low pressure section via a valve member driven by the intake valve rocker arm.

<Operation> During engine braking, the auxiliary exhaust valve drive device operates by the hydraulic control valve to keep the auxiliary exhaust valve open. However, when the intake valve is in the open state, the auxiliary exhaust passage closing means closes the auxiliary exhaust valve.

<Example> Fig. 1 shows a schematic structure showing the main parts of an engine braking device according to an embodiment of the present invention, and Fig. 2 a
2 shows the schematic structure of the auxiliary exhaust passage blocking means, FIG. 2b shows the concept of its operation when the intake valve is closed in its cross section taken along the - line, and FIG. Concept: FIG. 3 shows the valve opening process of the engine braking device shown in FIG.

An intake passage 12, an exhaust passage 13, and an auxiliary exhaust passage 14 communicate with the combustion chamber 11, and the auxiliary exhaust passage 14 is connected to the exhaust passage 13 midway. An intake valve 15 and an exhaust valve 16 for opening and closing the intake passage 12 and the exhaust passage 13 are provided at the openings of the intake passage 12 and the exhaust passage 13 with the combustion chamber 11, and the intake valve 15 and the exhaust valve 16 are provided with valve springs (not shown). A spring force is always applied to close the intake passage 12 and the exhaust passage 13 at , and against this spring force, the locker arms 19 and 20 open the intake valves 15 and 16 in synchronization with the movement of the piston 17. It is now forced to open.

On the other hand, an auxiliary exhaust valve 1 for opening and closing the auxiliary exhaust passage 14 is provided at the opening of the auxiliary exhaust passage 14 with the combustion chamber 11.
8, and the auxiliary exhaust valve 18 is biased by a valve spring (not shown) with a spring force that always closes the auxiliary exhaust passage 14. A locking bracket 21 on which the locking arms 19 and 20 are supported is provided with an oil passage 23 that communicates a hydraulic pump 22 operated by a control device 25 that detects the engine braking state with the auxiliary exhaust valve 18. That is, one end of the oil passage 23 is connected to the auxiliary exhaust valve stem portion 18 of the auxiliary exhaust valve 18.
The other end communicates with the hydraulic pressure receiving part 18b of a, and the other end communicates with the hydraulic pump 22. A solenoid valve 26 as a hydraulic control valve is provided in the middle part of the oil passage 23.
6 is operated during engine braking to keep the auxiliary exhaust valve 18 open. When the hydraulic pump 22 operates, the auxiliary exhaust valve 18 is opened via the electromagnetic valve 26 and the oil passage 23. In other words, the auxiliary exhaust valve drive device includes a hydraulic pump 22, an oil passage 23, and a solenoid valve 26.
It is composed of. Also, Rotsuka Arm 19
is provided with a discharge passage 24 that communicates with the oil passage 23 when the intake valve 15 is tilted to open. In other words, even if the hydraulic pump 22 is operated, when the intake valve 15 is opened, the pressure oil sent to the oil passage 23 is discharged from the discharge passage 24 and does not act on the auxiliary exhaust valve 18. The exhaust passage 24 becomes a closed state, and the exhaust passage 24 serves as means for closing the auxiliary exhaust passage. The exhaust system is provided with an exhaust brake valve (not shown).

In the engine brake device configured in this way, when the control device 25 determines the engine brake state, the operation of the fuel injection device is stopped, and the hydraulic pump 22 is activated to open the auxiliary exhaust valve 18. . This increases the resistance during the compression process and enhances the engine braking effect due to compression work. Further, when the intake valve 15 is in an open state, the oil passage 23 and the discharge passage 24 are communicated with each other and the hydraulic pump 2
The pressure oil from 2 is led from an oil passage 23 to a discharge passage 24 and discharged. As a result, when the intake valve 15 is open, the pressure oil does not act on the auxiliary exhaust valve 18 and the auxiliary exhaust valve 1
8 is in a closed state, and there is no possibility that exhaust pressure will flow back into the intake system during the intake process.

As shown in FIG. 4, the auxiliary exhaust passage closing means is operated by moving the ball 28b to the oil passage 23 of the locking bracket 21 by moving the pin 23a to open and close the exhaust valve 29 communicating with the exhaust passage 24. Provided opposite to 19, the locking arm 19
A groove 30 is provided in which one end of the pin 28a enters, the groove 30 facing the pin 28a is made shallow when the intake valve 15 is in the open state, and the pin 28 is moved when the intake valve 15 is in the open state. The discharge valve 29 may be opened by moving the ball 28b (the state shown by the dotted line in FIG. 4B), the pressure oil may be discharged from the discharge passage 24, and the auxiliary exhaust valve 18 may be closed.

<Effects of the invention> The engine braking device of the present invention uses hydraulic pressure to open the auxiliary exhaust passage when the engine brake is to be applied, and the auxiliary exhaust valve is closed when the intake valve is open. Exhaust pressure does not flow back into the intake system. As a result, the exhaust pressure does not decrease and the absorption capacity increases significantly.
It becomes possible to apply engine braking rationally and efficiently. Further, there is no need to newly provide a complicated mechanism to the valve mechanism, and costs can be reduced. In addition, since the auxiliary exhaust passage blocking means that closes the auxiliary exhaust passage with the auxiliary exhaust valve when the intake valve opens is activated by the swing of the intake rocker arm, it is possible to always close the auxiliary exhaust valve at the correct timing. .

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the structure of the main parts of an engine braking device according to an embodiment of the present invention, FIG. 2 a is a conceptual diagram showing the structure of the auxiliary exhaust passage closing means, and FIG. Fig. 2c is a conceptual diagram of the operation when the intake valve is closed in the - line cross section in a.
A conceptual diagram of the operation when the intake valve is open in the - line cross section in Figure a, Figure 3 is a valve opening process diagram of the engine braking device shown in Figure 1, and Figure 4a is an auxiliary exhaust passage using an exhaust valve. A conceptual diagram showing the structure of the closing means, FIG. 4b is an enlarged view of section A in FIG. 4a. In the drawing, 11 is a combustion chamber, 12 is an intake passage, 13
14 is an exhaust passage, 14 is an auxiliary exhaust passage, 15 is an intake valve, 16 is an exhaust valve, 17 is a piston, 18 is an auxiliary exhaust valve, 22 is a hydraulic pump, 24 is an exhaust passage, 25
27 is a control device, 27 is a solenoid valve, and 29 is a discharge valve.

Claims (1)

[Scope of utility model registration request] An auxiliary exhaust passage whose both ends communicate with the combustion chamber and the exhaust passage of the engine, an auxiliary exhaust valve provided reciprocally to open and close the auxiliary exhaust passage, and one end of which is a hydraulic receiver of the auxiliary exhaust valve stem. an auxiliary exhaust valve drive device comprising an oil passage whose other end communicates with a hydraulic pump and a hydraulic control valve provided at an intermediate portion of the oil passage; a control device that operates the hydraulic control valve during engine braking to maintain the auxiliary exhaust valve in an open state and stops supplying fuel to the combustion chamber; The intake valve rocker arm to be driven and the oil passage near the oil pressure receiving part communicated with a low pressure part through a valve member driven by the intake valve rocker arm only when the intake valve rocker arm swings during engine braking. and auxiliary exhaust passage closing means for closing the auxiliary exhaust passage with the auxiliary exhaust valve.