JPH0322515Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) This invention relates to improvement of a supercharging device for an internal combustion engine.

(Background technology) In order to improve engine output in diesel engines,
For example, there are some that use a turbo supercharger.

In general, it is better to use a low-speed turbocharger to improve the response delay of supercharging during sudden acceleration, etc. However, compared to a high-speed type, a low-speed type tends to have more supercharging than necessary in the partial load range. As a result, there is a problem that pumping loss increases and fuel efficiency worsens.

Therefore, in order to improve fuel efficiency in the partial load range and supercharging response delay during sudden acceleration in diesel engines, a high-speed turbo supercharger was adopted and configured as shown in Figure 1. This was proposed in Japanese Utility Model Application Publication No. 58-181936.

To explain this, 1 is the engine body, 2 is a high-speed turbo supercharger, 3 is an intake manifold, and 4 is an exhaust manifold.

A high pressure passage 7 communicating with a high pressure air tank 6 is connected to the intake passage 5 immediately upstream of the intake manifold 3, and a normally closed valve (electromagnetic valve) 8 is installed in the middle of this passage 7.
is interposed.

Normally closed valve 8 is connected to control device 1 via relay 9.
Opening/closing is controlled by 0.

Based on input signals from an engine rotation sensor 11 and a load sensor 12, a control device 10 outputs an ON signal to a relay 9 in a low rotation and high load range to open a normally closed valve 8.

Therefore, when moving from low speed driving to accelerated driving,
Control device 10 opens normally closed valve 8 via relay 9 .

As a result, high-pressure air is also supplied from the high-pressure air tank 6 to the intake manifold 3, so that the boost pressure rises quickly as shown in FIG. 2, and the response delay of the turbocharger is improved.

However, when supercharging air is supplied to the intake passage in this way, leakage of supercharging air due to overlapping of the intake and exhaust valves cannot be ignored, and the capacity of the high-pressure tank is required to secure the specified amount of supercharging. It has the disadvantage of being extremely large.

By the way, in a diesel engine, a compression brake device as shown in Fig. 3 is adopted to utilize the engine brake.
56-126640).

13 is a combustion chamber, 14 is a piston, 15 is an intake valve, and 16 is an exhaust valve.The intake and exhaust valves 15 and 16 are synchronized with the engine rotation by the rotation of a camshaft (not shown) via rocker arms 17 and 18 to achieve a predetermined valve timing. Open and close with .

In addition to the intake and exhaust ports 19 and 20, a relief port 21 is opened in the combustion chamber 13, and a third valve 22 is disposed at the opening of the relief port 21.

The third valve 22 is driven by a camshaft via a rocker arm 23, like the intake and exhaust valves 15 and 16, and opens near the top dead center of the compression process.

The valve operating mechanism of the third valve 22 is provided with a device (not shown) that absorbs the valve lift when the engine brake is not activated, that is, stops the opening/closing operation of the third valve 22.

Therefore, when the engine brake is activated, the third valve 2
When valve 22 opens near the top dead center of the compression process, compressed air (fuel injection is cut off) in the combustion chamber 13 escapes through this valve 22.

Therefore, the amount of work required to lower the piston 14 from the top dead center to the bottom dead center increases (losses in the compression process cannot be recovered), and as a result, engine braking becomes more effective.

By the way, in the above-mentioned diesel engine with a turbocharger, the compressor 55 is driven and high pressure air for supercharging is stored in the high pressure air tank 6, but for this reason, the engine output is required to drive the compressor 55. There was a problem that the data was lost.

(Purpose of the invention) This invention was devised by focusing on these problems, and is based on an internal combustion engine equipped with a compression brake system, in which the compressed air that escapes from the combustion chamber through the third valve is stored in a high-pressure tank. An object of the present invention is to provide a supercharging device for an internal combustion engine that saves driving force of a compressor by reusing high-pressure air for supercharging.

(Structure and operation of the device) Therefore, this device provides a third valve together with the intake and exhaust valves in the combustion chamber, forms a high-pressure passage that connects the combustion chamber and the high-pressure air source via the third valve, and control means for opening the third valve for a predetermined period at the beginning of the compression stroke when the engine is at low speed and high load, and for opening the third valve for a predetermined period at the beginning and end of the compression stroke when the engine is decelerating. and control means.

In other words, when the engine brake is activated (during deceleration),
When the third valve opens near the top dead center of the compression stroke, the compressed air escaping from the combustion chamber via the third valve is stored in the high-pressure air source.

Then, when the vehicle starts accelerating, this compressed air is supplied to the combustion chamber as high-pressure air for supercharging via the third valve, which opens at the beginning of the compression stroke.

(Example) Hereinafter, this invention will be explained according to an example in which this invention is applied to a turbocharged diesel engine shown in FIGS. 4 to 6.
Note that the same parts as in FIG. 1 are given the same reference numerals.

In FIG. 4, 13 is the combustion chamber of the engine body 1;
15 is its intake valve, 16 is its exhaust valve, and 2 is a high-speed turbo supercharger.

The combustion chamber 13 is communicated with the high pressure air tank 6 via a high pressure passage 25, and a third valve 26 is disposed at the opening of the high pressure passage 25 on the combustion chamber 13 side.

The third valve 26 is driven and controlled by a control device 27, which will be described later, and opens for a predetermined period near the bottom dead center of the compression process in synchronization with engine rotation during acceleration, supercharging the combustion chamber 13 with high-pressure air from the high-pressure air tank 6. On the other hand, during deceleration, the combustion chamber 13 opens for a predetermined period near the bottom dead center and top dead center of the compression process.
This compressed air is released to a high-pressure air tank 6 to improve the efficiency of engine braking.

As shown in FIG. 5, the third valve 26 has a valve shaft 26A.
An oil chamber (cylinder) 29 formed in the upper part of the cylinder head 28 is provided with a freely sliding piston 30, which opens and closes integrally with the piston 30 in response to the oil pressure in the oil chamber 29. 58 indicates a return spring.

The oil chamber 29 is connected to the hydraulic circuit 3 as shown in FIG.
1 and 32 via the first and second piston pumps 3
3 and 34.

The first and second piston pumps 33 and 34 are connected to the first and second camshafts 36 of the camshaft 35,
When the pistons 38 and 39 are pushed up by the cam 37 (formed separately from the cam of the intake and exhaust valves), hydraulic pressure is supplied to the oil chamber 29.

The first cam 36 has a cam profile that lifts the piston 38 for a predetermined period near the bottom dead center of the compression stroke in synchronization with engine rotation, and the second cam 37 similarly lifts the piston 39 near the top dead center of the compression stroke. Each is set in the cam profile to be used.

Relief valves 40, 41 are provided in the hydraulic circuits 31, 32.
Return passages 42, 43 are connected to release the pressure oil from the piston pumps 33, 34 to the tank side when the valves are opened, and the relief valves 40, 41 open when pilot pressure is supplied via the solenoid valves 44, 45. ing.

A control device drives and controls the solenoid valves 44 and 45, and the control device 27 controls one solenoid valve 44 during acceleration and both solenoid valves 44 during deceleration based on input signals from the engine rotation sensor 11 and load sensor 12. , 45 to stop the supply of pilot pressure to the relief valve 40 or 40, 41.

Reference numerals 56 and 57 are cutoff valves that open when pilot pressure is supplied via the solenoid valves 44 and 45, and 46 and 47 are replenishment passages for replenishing the hydraulic oil that has escaped to the tank side via the relief valves 40 and 41. Pilot pressure is also supplied to relief valves 40, 41 and cutoff valves 56, 57 via 44, 45. 50 to 53 indicate check valves.

Next, the action will be explained.

For example, when the vehicle shifts from low-speed travel to accelerated travel, the control device 27 closes the relief valve 40 via the solenoid valve 44.

Along with this, hydraulic pressure from the piston pump 33 is supplied to the oil chamber 29, and the third valve 26 opens for a predetermined period near the bottom dead center of the compression stroke in synchronization with the engine rotation, as shown by the solid line in FIG. .

This allows the third valve 26 to be removed from the high pressure air tank 6.
High-pressure air is directly supplied to the combustion chamber 13 through Response delay (turbo lag) is improved.

In this case, the high pressure air from the high pressure air tank 6 is directly supplied to the combustion chamber 13.
Unlike the case where the air is supplied through the intake manifold 3 as shown in Fig. 3, there is no leakage into the intake and exhaust system, and therefore, the amount of air in the combustion chamber 13 rises rapidly.
Turbo lag can be further improved.

On the other hand, the control device 27 closes the relief valve 41 together with the relief valve 40 via the electromagnetic valves 44 and 45 during deceleration.

As a result, the hydraulic pressure from the piston pump 34 is supplied to the oil chamber 29, and the third valve 26 opens for a predetermined period even near the top dead center of the compression stroke in synchronization with the engine rotation, as shown by the dotted line in FIG.

Therefore, the supercharged air at the beginning of the compression process is
After being compressed to high pressure in the combustion chamber 13 as the piston 14 rises, it escapes to the high-pressure air tank 6 via the third valve 26 near the end of compression.

Therefore, as shown in Fig. 8, the amount of work required to push the piston 14 back to bottom dead center increases due to the increase in work during the compression stroke and the decrease in pressure within the combustion chamber 13 during the expansion stroke. As a result, engine braking becomes more effective.

By the way, in this embodiment, when the engine brake is activated, the compressed air that escapes from the combustion chamber 13 through the third valve 26 is stored in the high-pressure air tank 6 as described above, and during acceleration, this is combusted as high-pressure air for supercharging. Since the air is supplied to the chamber 13, the driving force required for the compressor 55 of the high-pressure air tank 6 can be significantly reduced compared to the conventional case (FIG. 1).

Note that the relief valves 40 and 41 are opened except during acceleration and deceleration, the pressure oil from the piston pumps 33 and 34 does not act on the oil chamber 29, and the normally closed valve 26 is in the closed position and its operation is stopped.

Although the present invention has been described above using an example in which it is applied to a turbocharged diesel engine, it is clear that the present invention can be applied to internal combustion engines in general, regardless of whether or not turbocharged engines are used.

(Effects of the invention) In summary, according to this invention, it is possible to efficiently supercharge through the third valve during acceleration, improving the acceleration response of the engine, while at the same time, during engine braking, high-pressure air is blown into the initial stage of compression. This provides a powerful compression braking effect, and the air released during braking is reused as high-pressure air for supercharging, resulting in a significant saving in the driving force of the compressor that generates high-pressure air.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a conventional device, Fig. 2 is a boost pressure characteristic diagram thereof, Fig. 3 is a sectional view of main parts of another conventional device, and Fig. 4 is a schematic configuration diagram showing an embodiment of this invention. , Fig. 5 is a sectional view of its main parts, Fig. 6 is a hydraulic circuit diagram, Fig. 7 is a control characteristic diagram of a normally closed valve, and Fig. 8 is a diagram of control characteristics of a normally closed valve.
The figure is a PV diagram when the engine brake is activated. 1... Engine body, 2... Turbo supercharger, 6...
High pressure air tank, 13... Combustion chamber, 25... High pressure passage, 26... Third valve, 27... Control device, 29... Oil chamber, 30... Piston, 31,3
2... Hydraulic circuit, 33, 34... Piston pump, 35... Camshaft, 36, 37... Cam, 40, 41... Relief valve, 44, 45...
Solenoid valve, 56, 57... shutoff valve.

Claims (1)

[Scope of utility model registration request] A third valve is provided in the combustion chamber along with the intake and exhaust valves to form a high pressure passage connecting the combustion chamber and the high pressure air source via the third valve.Means for detecting the engine operating state are also provided, and when the engine is running at low speed and under high load, An internal combustion engine characterized by comprising a control means for opening three valves for a predetermined period at the beginning of a compression stroke, and a control means for opening the third valve for a predetermined period at the beginning and end of a compression stroke when the engine decelerates. supercharging device.