JPS60182323A - Power increasing device of exhaust-gas brake - Google Patents

Abstract

PURPOSE:To magnify power of an exhaust-gas brake, by providing a valve, which opens when a piston is placed in the vicinity of the top dead center in a compression stroke, and a check valve, which allows a circulative flow only into a cylinder, in each cylinder and suitably connecting the valve to the check valve when the exhaust-gas brake is applied. CONSTITUTION:A valve 1, which opens when a piston is placed in the vicinity of the top dead center in a compression stroke, and a check valve 2, which allows a circulative flow only into a cylinder, are provided in each cylinder of an engine and suitably connected when an exhaust-gas brake is applied. Further said valve 1 in a cylinder, whose piston is placed in the vicinity of the top dead center in the compression stroke, and the check valve 2 in another cylinder, whose piston is placed in the beginning of the compression stroke when the piston of the former cylinder is placed in the vicinity of the top dead center in the compression stroke, are provided in each communicating passage 3a. If an exhaust-gas brake switch 42 is turned on, a solenoid valve 40 is closed, and the pressure of oil, being supplied to a cylinder 12, opens the valve 1. Then compressed air in a combustion chamber 9, being allowed to flow in the passage 3a, opens the check valve 2 to flow into another combustion chamber 9, increasing the pressure in its cylinder thus magnifying power of the exhaust-gas brake.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an exhaust braking force increasing device, and in particular, when the piston of each cylinder reaches near the compression top dead center, the pressure inside the cylinder is reduced to increase the exhaust braking force. The present invention relates to an engine exhaust braking force increasing device.

[Prior art]

In general, for engines installed in large and medium-sized vehicles such as trunks and buses (1), if the foot brake is used frequently to brake the vehicle when going down a slope or when driving at high speed, a fade phenomenon will occur, so the engine Exhaust brakes are used to block the flow of exhaust gas by installing a butterfly valve or slide valve in the exhaust passage, and apply brakes to the engine to brake the vehicle. Exhaust braking is used to release gas from the combustion chamber of a cylinder, dissipating the energy stored in the form of pressure and applying brakes to the engine.

On the other hand, in recent years, the engines of vehicles such as trucks and buses have been equipped with superchargers to improve the output of the engines, and these have become effective for driving on the road.

However, when the engine output is increased by a supercharger, drivers tend to think that the exhaust braking force is also increasing, but in reality, the exhaust braking force remains the same, so when going down a slope, etc. The problem is that the exhaust brake feels less effective (2), forcing the driver to use the foot brake frequently.

Therefore, a measure can be taken to increase the set value of the opening pressure of the valve installed in the exhaust passage, but this measure has the problem that the valve train system such as the intake valve and the exhaust valve must be strengthened. Furthermore, an exhaust brake device that combines a conventional exhaust brake that dams up exhaust gas and an exhaust brake that decompresses a cylinder at the top dead center of the compression stroke is found in Japanese Patent Application Laid-Open No. 171011/1982. This device has the disadvantage that it has a complicated structure and the degree of improvement in exhaust braking force is not that great.

[Object and structure of the invention]

The purpose of the present invention is to eliminate the ineffectiveness of the exhaust brake in conventional engines that are equipped with a supercharger to improve output, and to eliminate the need for two types of exhaust brakes in engines with high output. We have created an excellent exhaust brake force increase device that can apply a very large exhaust brake force (3) by simply adding a simple device to the exhaust brake that depressurizes the cylinder at the top dead center of the compression stroke. It is to provide.

To achieve the above object, the present invention provides each cylinder with a valve that opens near the top dead center of the compression stroke when the exhaust brake is activated, and a reverse 1F valve that only allows flow into the cylinder.
The present invention is characterized in that a passage is provided which communicates the valve of the cylinder near the top dead center of the compression stroke with the check valve of the cylinder at the beginning of the compression stroke.

〔Example〕

The present invention will be described in detail below using the accompanying drawings.

First, the basic configuration and operation of the exhaust braking force increasing device of the present invention will be explained in the case of a 4-stroke inline 6-cylinder engine. In this case, the ignition order for a 6-cylinder engine is the most common #1 → #5-#3-#6-#2-#
It is assumed that the four cylinders are arranged in this order and are equally spaced by 120°, and the opening timings of the intake and exhaust valves are as shown by the bands in FIG.

(4) As can be seen from this diagram, the #1 cylinder enters the compression stroke after its intake valve closes, and by the time it reaches the top dead center of the compression stroke (time T3), where the cylinder pressure is highest, the ignition order is next. The #5 cylinder is at the beginning of the compression stroke with its intake valve closed. Similarly, when #5 cylinder is at the top dead center of the compression stroke (time 'r, t
), it can be seen that the #3 cylinder, which follows the #5 cylinder in the ignition order, is at the beginning of the compression stroke. That is, in a normal in-line six-cylinder engine, by the time a certain cylinder is at compression top dead center, the next cylinder in the ignition order is at the beginning of the compression stroke.

Therefore, as shown in Fig. 2, each cylinder of an in-line six-cylinder engine equipped with an exhaust brake is provided with a valve 1 that opens near compression top dead center of that cylinder when the exhaust brake switch is turned on. If the high-pressure air discharged from the cylinder 1 is introduced into the next cylinder in the ignition order through the connecting pipe 3 in which the check valve 2 is installed, the pressure at the top dead center of the compression stroke of that cylinder will be equal to that of the previous cylinder. The pressure will rise above the pressure at dead center.

(5) Figures 3 and 4 are P-θ diagrams of the #1 cylinder and #5 cylinder when each cylinder of the engine is connected by the connecting pipe 3 as described above. This shows the characteristics when the exhaust brake switch is turned on when the first cylinder is in the compression stroke, and FIG. 4 shows the characteristics of the #5 cylinder immediately after that. In these figures, the dotted line shows the normal P-θ characteristic when the exhaust brake is not operating, and the solid line shows the P-θ characteristic when the exhaust brake switch is turned on.

Point A in FIG. 3 is the point when valve 1 opens near the top dead center of the compression stroke of cylinder #1. After this, compressed air is discharged from cylinder #1 through connecting pipe 3, so It can be seen from this figure that the internal pressure drops rapidly. and,
Compressed air discharged from the #1 cylinder flows into the #5 cylinder through the connecting pipe 3, so the pressure in the #5 cylinder changes from point B at the beginning of the compression stroke (same time as point A in Figure 3) to the normal level. It can be seen from FIG. 4 that it exceeds the P-〇 characteristic.

(6) The 0 point in Figure 4 is the point at which valve 1 opens at the top dead center of the compression stroke of the #5 cylinder, and the P-θ characteristic of the #5 cylinder then sharply changes like the characteristic in Figure 3. It is declining. Since the compressed air of the #5 cylinder flows into the next ignition cylinder, ie, the #3 cylinder, through the connecting pipe 3, the pressure characteristics of the compression stroke of the #3 cylinder exceed those of the #5 cylinder.

Figure 5 shows how the P-V characteristics of each cylinder change due to the exhaust braking force increasing device of the present invention that operates as described above. is shown over one period.

As can be seen from this figure, according to the exhaust braking force increasing device of the present invention, as the engine rotates, the initial pressure in the compression stroke of each cylinder will always exceed the initial pressure of the cylinder before it in the ignition order. , the compression work of the piston gradually increases, and the pressure that has increased near the compression top dead center is rapidly reduced, so that the large rotational energy obtained in the compression stroke is lost7). A gradually larger exhaust braking force acts on the engine each time the engine rotates.

Therefore, in the exhaust brake force increasing device of the present invention, when the exhaust brake is applied, even a part of the compressed air in the cylinder near the top dead center of the compression stroke is guided to the next cylinder in the ignition order, and the pressure in that cylinder is increased. If the pressure characteristics are made even slightly higher than the pressure characteristics of the previous cylinder, the effect of increasing exhaust braking will appear in a short time due to the high-speed engine. Since the degree of increase in exhaust braking force is determined by the amount of compressed air introduced into the next cylinder in the ignition order, the amount introduced may be set in accordance with the output of the installed engine.

FIGS. 6 and 7 show a specific configuration for one cylinder for realizing the exhaust brake force increasing device of the present invention which functions as described above.

FIG. 6 shows the mounting locations of each component constituting the exhaust brake force increasing device of the present invention. Engine (8) The valve 1 provided in the cylinder head 4 of the engine is installed so as not to interfere with the intake/exhaust valve device 5, and the opening of the combustion chamber 9 of the communication port 3a provided in the cylinder head 4. The parts are designed to open and close. Each communication port 3a is provided with a communication pipe 3 that communicates with the next cylinder in the ignition order. Further, a hydraulic device 30 that opens the valve 1 when the piston 6 reaches the top dead center of the compression stroke is installed in the cylinder block 8 near the cam 7 that operates the intake valve 5K.

FIG. 7 is an enlarged view of each component constituting the exhaust brake force increasing device of FIG. 6. A poppet valve 11 is used for the valve 1 installed to open and close the openings of the nine combustion chambers of the communication port 3a provided in the cylinder head 4. A piston 13 that slides inside a hydraulic cylinder 12 provided in the hydraulic cylinder 12 is provided so as to protrude from the piston 13, and is normally biased by a spring 14 installed in the lower part of the hydraulic cylinder 12 so that its valve body is connected to the valve provided in the opening. It is pressed onto the sheet 15 to close the opening (9).

Further, in this embodiment, a poppet valve 21 is used for the reverse valve 2 provided in each cylinder, and this poppet valve 21
The valve body is always pressed from the combustion chamber 9 side to a valve seat 23 provided at the opening of the communication port 3a by a spring 22 installed between the end thereof and the cylinder head 4. Therefore, the poppet valve 21 does not open even if the pressure inside the combustion chamber 9 becomes high, but it opens only when the pressure on the communication port 1-3a side increases.

On the other hand, a hydraulic device 30 installed near the cam 7 for actuating the intake valve is connected to a cylinder 3 bored in the cylinder block 8.
A roller piston 32 is slidably provided on the cylinder 1 and has a roller 33 attached to its tip; a spring 34 is installed inside the cylinder 31 and keeps the roller 33 in pressure contact with the cam 7; An oil supply path 37 equipped with a check valve 36 that supplies pressurized oil from an oil gear gallery 35, a hydraulic oil supply pipe 38 connecting the hydraulic device 30 and the valve 1, and a hydraulic oil supply pipe 38 (1
0) and a reflux pipe 45 provided with an electromagnetic on-off valve 40 branching from the reflux pipe 45. The hydraulic device 30 is attached to the cylinder block 8 so that the cam nose 7a of the cam 7 contacts the roller 33 near the top dead center of the compression stroke of the cylinder. 39 is an oil pump,
29 is an oil pan.

The electromagnetic on-off valve 40 is configured such that its solenoid portion 41 is open when not energized and communicates with the return pipe 45, and when the return pipe 45 is in communication, the hydraulic oil flowing through the hydraulic oil supply pipe 38 is communicated with the return pipe 45. The oil does not flow to the valve 1 side, and the entire amount is returned to the pipe 4.
5 and is returned to the oil pan 29. Further, the solenoid section 41 is connected to an exhaust brake switch 42.
It is connected to the pantry 43 via the exhaust brake valve 43, and when the exhaust brake valve cassette 42 is turned on, it is energized and the electromagnetic on-off valve 4
0 is closed and the hydraulic system 30 is connected via the hydraulic oil supply pipe 38.
The oil from the valve is allowed to flow to the valve l'.

In the exhaust brake force increasing device of this embodiment configured as described above, when the exhaust brake switch 42 is turned on, the electromagnetic on-off valve 40 closes, so the cam 7 rotates with the rotation of the engine, and the cylinder When reaches near the top dead center of the compression stroke, the cam nose 7a causes the roller piston 32 to sink into the cylinder 31, and as a result, the oil in the cylinder 32 passes through the hydraulic oil supply pipe 38 in a continuous line to the valve l. introduced into the cylinder 12. The piston 13 is pushed down by this oil, the poppet valve 11 is moved away from the valve seam 5, and the compressed air in the combustion chamber 9 is communicated with the valve seam 5).
run away to a. The compressed air introduced into the communication port) 3a passes through the communication pipe 3 to the communication port of the next cylinder in the ignition order.
a, the poppet valve 21 of the check valve 2 is pushed down to enter the combustion chamber 9, and the pressure of the next cylinder in the ignition order is increased.

When the cam nose 7a passes the roller piston 32,
The roller piston 32 is pushed out of the cylinder 31 by the spring 34, increasing the volume of the cylinder 32, and the piston 13 of the valve 1 is also urged by the spring 14 to try to reduce the volume of the cylinder 2. The oil in the cylinder 2 flows backward through the hydraulic oil supply pipe 38 and returns to the cylinder 31 of the hydraulic device 30, and the valve 1 is closed. From then on, such an operation is repeated every time the cylinder reaches near the top dead center of the compression stroke.

When the exhaust brake switch is turned off, the solenoid on-off valve 4
Since the valve 0 is opened and the hydraulic device 30 is communicated with the oil pan 29 via the return pipe 45, the oil in the hydraulic device 30 no longer flows to the valve 1, and the valve 1 will not open.

If the device configured as described above is used, the exhaust brake force will be increased by the action of the exhaust brake force increasing device when the exhaust brake switch is turned on as described above, so the driver of a vehicle equipped with a high output engine can This eliminates the feeling of insufficient exhaust braking force and allows the vehicle to be driven safely without frequent use of the foot brake.

〔Effect of the invention〕

(13) As explained above, the exhaust brake force increasing device of the present invention includes a valve that opens near the top dead center of the compression stroke when the exhaust brake is activated, and a check valve that only allows flow into the cylinder. By providing passages that communicate with the valves of the cylinders near the top dead center of the compression stroke and the check valves of the cylinders at the beginning of the compression stroke, the exhaust gas is reduced in high-output engines. Since the braking force can be increased and the exhaust braking force commensurate with the output can be applied, the driver can safely drive the vehicle.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the opening period of the intake valve and exhaust valve in the most common ignition order of a 4-cycle in-line 6-cylinder engine, and Fig. 2 is an explanatory diagram showing the opening period of the intake valve and exhaust valve in the most common ignition order of a 4-cycle in-line 6-cylinder engine. Schematic diagrams of the basic configuration when applied, Figures 3 and 4 show the #1 cylinder, #(14), and #5 cylinder P immediately after the exhaust brake switch of the engine configured as shown in Figure 2 is turned on. -θ diagram; FIG. 5 is a diagram showing the p-v characteristics of each cylinder over time for one cycle immediately after the exhaust brake switch of the device shown in FIG. 2 is turned on; FIG. FIG. 7 is a sectional view of an engine showing a specific embodiment of the exhaust brake force increasing device for one cylinder, and FIG. 7 is an explanatory diagram showing an enlarged view of the configuration and connections of the components shown in FIG. 6. l... Valve, 2... Check valve, 3... Connecting pipe, 3
a...Communication boat, 4...Cylinder head, 6...
・Bis I・N, 7...Cam, 30...Hydraulic system, 4
0...Electromagnetic three-way valve, 42...Exhaust brake switch. Agent: Patent Attorney Shin Ogawa − Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita (15)

Claims (1)

[Claims] Each cylinder is provided with a valve that opens near the top dead center of the compression stroke when the exhaust brake is activated, and a check valve that only allows flow into the cylinder. , an exhaust braking force increasing device characterized in that a passage is provided which communicates with the check valves of the cylinders which are in the initial stage of the compression stroke at this time.