JPH09125995A - Compression pressure release type engine assist brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep accumulator internal pressure at a high level and constant at all times, and improve responsiveness for increasing an engine brake force by connecting an accumulator to a common rail via a pressure regulation piston capable of transmitting only pressure, so as to keep the internal pressure of the accumulator constant due to the internal pressure of the common rail. SOLUTION: High-pressure fuel is supplied from a high-pressure supply pump to a common rail 27, and the high-pressure fuel is introduced to an injector. An accumulator 24 is connected to the common rail 27 via a pressure regulation piston 28 capable of transmitting only pressure, so as to keep the internal pressure of the accumulator 24 constant due to the internal pressure of the common rail 27. Furthermore, even when a leakage takes place at a delay piston 25 after the temporary stop of an assist brake, the internal pressure of the accumulator 24 is always kept at a high level and constant. According to this construction, accumulator internal pressure can always be kept at a high level as well as constant. Also, responsiveness can be improved to increase an engine brake force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compression pressure release type engine auxiliary braking device.

[0002]

2. Description of the Related Art In recent years, in a diesel engine mounted on a large vehicle such as a bus, a compression pressure release type engine auxiliary braking device may be provided in order to increase the effects of engine braking and exhaust braking.

As shown in FIG. 3, in the compression pressure release type engine auxiliary brake device 1, with the auxiliary brake switch 2 turned on, the accelerator pedal is released and the accelerator switch 3 is turned on, and the transmission (not shown) is shown. ) Is in a position other than neutral, the neutral switch 4 is turned off, the clutch pedal (not shown) is released, the clutch switch 5 is turned on, and the engine speed detected by the rotation sensor 6 is preset. When the auxiliary brake cut rotation speed is equal to or higher than the auxiliary brake cut rotation speed, based on the auxiliary brake operation signal output from the auxiliary brake controller 7 through the auxiliary brake operation signal line 8, the piston 9 operates near the compression top dead center to open the exhaust valve 10. The pressure inside the cylinder is reduced by letting compressed air escape. In the next expansion stroke, the energy for lowering the piston 9 is reduced, so that increasing the engine braking force.

An example of the specific structure and operation of the conventionally known compression pressure release type engine auxiliary brake device 1 will be described. As shown in FIG. 4, the auxiliary brake controller 7 connects the auxiliary brake operation signal line 8 to the auxiliary brake operation signal line 8. Solenoid valve 1 by the auxiliary brake actuation signal output via
1, the hydraulic pressure from the rocker support pushes up the control valve 12 and the check valve 13 inside the control valve 12, the engine oil is supplied to the working oil passage 14, and the master piston 16 normally pushed up by the flat spring 15 , The urging force of the flat spring 15 is overcome by the supplied oil pressure of the engine oil, and it is pushed down until it comes into contact with the upper surface of the adjusting screw bolt 18 of the rocker arm 17, and thereafter, as shown in FIG. , Is pushed up by the upper surface of the adjusting screw bolt 18, the engine oil in the working oil passage 14 is pushed back, the pressure on the oil passage 19 side of the check valve 13 in the control valve 12 becomes higher than the pressure in the oil passage 20,
The check valve 13 closes the circuit, and the working oil passage 14
A hydraulic pressure is generated inside, and the hydraulic pressure further rises to push down the slave piston 21 to open the exhaust valve 10, and the output of the auxiliary brake actuation signal from the auxiliary brake controller 7 is stopped. When,
As shown in FIG. 6, the solenoid valve 11 is closed, the supply of engine oil from the rocker support is cut off,
The control valve 12 is pushed down by the control valve spring 22 to lower the hydraulic pressure in the working oil passage 14, and at the same time, the master piston 16 is pushed up to the flat spring 15 and is separated from the upper surface of the adjust screw bolt 18 of the rocker arm 17. The hydraulic pressure for opening the exhaust valve 10 is no longer generated.

In the conventional compression pressure release type engine auxiliary braking device 1 as shown in FIGS. 4 to 6, in order to increase the engine braking force, the exhaust valve 10 is used.
Ideally, it is ideally opened immediately before the compression top dead center of the piston 9 in order to effectively utilize the resistance in the compression stroke of the piston 9, and closed immediately in order to increase the resistance in the expansion stroke of the piston 9. Is.

However, in the case of the conventional compression pressure release type engine auxiliary braking device 1, the hydraulic pressure in the working oil passage 14 changes in a form interlocking with the pushing and pulling of the master piston 16, and is indicated by a virtual line in FIG. As shown, a comparatively gentle curve is drawn, and accordingly, the exhaust valve 10 is not opened and closed rapidly, and there is room for improvement.

Therefore, as shown in FIGS.
The operating oil is supplied from the operating oil passage 14 via the charge valve 23 and stores the hydraulic pressure, and the internal pressure of the accumulator 24 driven by the master piston 16 and transmitted through the delay piston 25. Trigger valve 2 leading to passage 14
6 is additionally provided, and is configured to drive the slave piston 21 by the hydraulic pressure in the oil passage 14 for operation generated by the operation of the trigger valve 26 to open the exhaust valve 10. Is being developed.

In the compression pressure release type engine auxiliary braking device 1 additionally provided with the accumulator 24 and the like, after the engine is started, the master piston 16 and the trigger valve 26 are actuated several times to charge the accumulator 24 through the charge valve 23. A certain amount of hydraulic pressure is gradually stored inside, and in this state, as shown in FIG. 8, when the solenoid valve 11 is opened by the auxiliary brake operation signal output from the auxiliary brake controller 7 through the auxiliary brake operation signal line 8, The hydraulic pressure from the rocker support is used for the control valve 12 and the check valve 13 inside the control valve 12.
The engine oil is supplied to the working oil passage 14, and the engine oil is supplied from the working oil passage 14 to the accumulator 24 via the charge valve 23.
The oil pressure in the accumulator 24 is further increased, and engine oil is supplied from the operating oil passage 14 into the trigger valve 26.
The master piston 16 pushed up by 5 is moved by the flat spring 1 by the oil pressure supplied by the engine oil.
It is pushed down until it comes into contact with the upper surface of the adjusting screw bolt 18 of the rocker arm 17 by overcoming the urging force of No. 5.

At the same time, as shown in FIG. 9, the trigger valve 26 is closed and the working oil passage 14 is shut off.
As the master piston 16 operates with the rocker arm 17,
When pushed up by the upper surface of the adjusting screw bolt 18, high-pressure engine oil passes through the inside of the trigger valve 26 and is pressure-fed to the delay piston 25, and the delay piston 25 moves downward in FIG. 9 and the accumulator 2
4. The internal pressure is increased. At this time, the delay piston 25
The accumulator 24 acts as a high pressure "spring", ready to actuate the slave piston at the appropriate time.

Then, when the master piston 16 is further pushed upward as shown in FIG. 10 in accordance with the operation of the rocker arm 17, the trigger valve 26 is opened, and the master valve 16 acts as a high-pressure "spring". Due to the operation of the delay piston 25 and the accumulator 24, high-pressure engine oil is pressure-fed from the delay piston 25 to the operating oil passage 14 via the trigger valve 26, and the pressure on the oil passage 19 side of the check valve 13 in the control valve 12 is increased. Becomes higher than the pressure in the oil passage 20, the check valve 13 closes the circuit, the pressure in the working oil passage 14 rises rapidly, and the slave piston 21 is pushed down instantly, and the exhaust valve 10 increases the compression of the piston 9. It is suddenly opened just before the dead point.

When the output of the auxiliary brake operation signal from the auxiliary brake controller 7 is stopped, as shown in FIG. 11, the solenoid valve 11 is closed, the supply of engine oil from the rocker support is shut off, and the control valve 12 is opened. It is pushed down by the control valve spring 22 to lower the hydraulic pressure in the operating oil passage 14, and at the same time the master piston 16 is pushed up by the flat spring 15 to hold the trigger valve 26 in an open state,
Moreover, the lower surface of the master piston 16 is separated from the upper surface of the adjusting screw bolt 18 of the rocker arm 17, and the hydraulic pressure for opening the exhaust valve 10 is not generated.

As a result, in the compression pressure release type engine auxiliary braking device 1 shown in FIGS. 8 to 11, the hydraulic pressure in the working oil passage 14 is as shown by the solid line in FIG.
Immediately before the compression top dead center of the piston 9, the exhaust valve 10 suddenly rises and descends, and the exhaust valve 10 is rapidly opened immediately before the compression top dead center of the piston 9 and immediately closed to prevent the resistance of the piston 9 in the compression stroke. Can be effectively used, and the resistance in the expansion stroke of the piston 9 can be increased, so that the engine braking force can be increased.

[0013]

In the case of the compression pressure release type engine auxiliary braking device 1 as shown in FIGS. 8 to 11, the accumulator 24 has a high internal pressure in order to operate the slave piston at a high pressure. Although it must be kept constant, leakage from the charge valve 23 and the delay piston 25 is unavoidable, and when the auxiliary brake is activated at the next time point, its responsiveness is slightly reduced and engine braking force is reduced. It may be difficult to raise the value sufficiently.

In view of the above situation, the present invention provides a compression pressure release type engine auxiliary braking device capable of keeping the internal pressure of the accumulator always high and constant, improving the responsiveness and enhancing the engine braking force. Is what you are trying to do.

[0015]

SUMMARY OF THE INVENTION The present invention is a solenoid valve which is opened and closed by an auxiliary brake operation signal output from an auxiliary brake controller via an auxiliary brake operation signal line, and which supplies and cuts off engine oil.
An operating oil passage to which engine oil is supplied from the solenoid valve via a control valve, an accumulator to which engine oil is supplied from the operating oil passage via a charge valve and stores hydraulic pressure, and a master driven by a rocker arm. Driven by a piston, a trigger valve driven by the master piston and guiding the accumulator internal pressure transmitted through a delay piston to the working oil passage, and hydraulic pressure in the working oil passage generated by the operation of the trigger valve. And a slave piston that opens the exhaust valve.The hydraulic pressure stored in the accumulator is used to drive the slave piston by operating the trigger valve, and the compression pressure that opens the exhaust valve near the compression top dead center of the piston. Open-ended engine An auxiliary braking device, in which high pressure fuel is supplied from a high pressure supply pump and the accumulator can be transmitted only to the common rail that guides the high pressure fuel to the injector so that the accumulator internal pressure is kept constant by the common rail internal pressure. The present invention relates to a compression pressure release type engine auxiliary braking device, which is characterized in that it is connected through a pressure regulating piston.

Further, according to the present invention, a solenoid valve which is opened and closed by an auxiliary brake operation signal output from an auxiliary brake controller via an auxiliary brake operation signal line, and which supplies and shuts off engine oil, and a control valve from the solenoid valve. A hydraulic oil passage for supplying engine oil via a high pressure fuel pump and a common rail which is supplied with high pressure fuel from the high pressure supply pump and guides the high pressure fuel to the injector. A master piston that is driven, a trigger valve that is driven by the master piston and that guides the common rail internal pressure that is transmitted through the pressure adjusting piston and the delay piston to the working oil passage, and is generated by the operation of the trigger valve. Depending on the hydraulic pressure in the working oil passage, It is equipped with a slave piston that is driven and opens the exhaust valve, and it is configured to use the internal pressure of the common rail to drive the slave piston by the operation of the trigger valve and open the exhaust valve near the compression top dead center of the piston. The present invention relates to a compression pressure release type engine auxiliary braking device.

According to the above means, the following effects can be obtained.

The internal pressure of the common rail is always kept high, and when the accumulator is connected to the common rail via a pressure adjusting piston, after the operation of the auxiliary brake is temporarily stopped, the accumulator is temporarily charged. Even if the engine oil leaked from the charge valve and the delay piston leaks, the accumulator internal pressure will always be kept high and constant, and the responsiveness will decrease when the auxiliary brake operates at the next time. Nothing happens, and it becomes possible to sufficiently enhance the engine braking force.

When the internal pressure of the common rail is directly utilized via the pressure adjusting piston, the internal pressure of the common rail, which is always kept at a high pressure, becomes the pressure adjusting piston due to the operation of the trigger valve even if an accumulator is not provided. Since it is transmitted to the slave piston via the delay piston, after the operation of the auxiliary brake is temporarily stopped, the responsiveness does not deteriorate when the auxiliary brake operates at the next point in time. Can be sufficiently increased.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an example of an embodiment for carrying out the present invention. In the figure, the parts denoted by the same reference numerals as those in FIGS. 8 to 11 represent the same things, and the basic structure is shown in FIG. Although it is similar to the conventional one shown in FIG. 11, the feature of the present example is that, as shown in FIG. 1, a high pressure fuel is supplied from a high pressure supply pump to a common rail 27 that guides the high pressure fuel to an injector. The point is that the accumulator 24 is connected via a pressure adjusting piston 28 capable of transmitting only pressure so that the internal pressure of the accumulator 24 is kept constant by the internal pressure of the common rail 27.

In FIG. 1, 29 is the pressure adjusting piston 28.
It is an oil seal fitted in.

Next, the operation of the illustrated example will be described.

The internal pressure of the common rail 27 is always maintained at a high pressure, and the accumulator 24 is connected to the common rail 27 via the pressure adjusting piston 28, so that
After the output of the auxiliary brake operation signal from the auxiliary brake controller 7 is stopped and the operation of the auxiliary brake is temporarily stopped, it is assumed that the engine oil filled in the accumulator 24 leaks from the charge valve 23 and the delay piston 25. However, the internal pressure of the accumulator 24 is always kept high and constant, and the responsiveness of the auxiliary brake is not deteriorated when the auxiliary brake is activated at the next time, and the engine braking force is sufficiently increased. Is possible.

In this way, the internal pressure of the accumulator 24 can always be kept high and constant, and the response can be improved to improve the engine braking force.

FIG. 2 shows another example of the embodiment of the present invention. In the figure, the parts designated by the same reference numerals as those in FIG. 1 represent the same things, and the accumulator 24 and the charge valve 2 are shown.
3, the delay piston 25 is connected to the pressure adjusting piston 28, and the internal pressure of the common rail 27 is transmitted to the slave piston 21 via the pressure adjusting piston 28 and the delay piston 25 by the operation of the trigger valve 26.
The exhaust valve 10 is configured to open in the vicinity of the compression top dead center.

In the example shown in FIG. 2, even if the accumulator 24 is not provided, the internal pressure of the common rail 27, which is always kept at a high pressure, is slaved by the operation of the trigger valve 26 via the pressure adjusting piston 28 and the delay piston 25. Since it is transmitted to the piston 21, the output of the auxiliary brake operation signal from the auxiliary brake controller 7 is stopped, and after the operation of the auxiliary brake is once stopped, the responsiveness of the auxiliary brake when the auxiliary brake operates at the next time point It does not decrease, and the engine braking force can be sufficiently increased.

Thus, the common rail 27 of the engine, which is always kept at a high pressure and constant, can be used as an accumulator without specially installing the dedicated accumulator 24, and the responsiveness is improved to improve the engine braking force. It can be planned.

It should be noted that the compression pressure release type engine auxiliary braking device of the present invention is not limited to the above-mentioned illustrated example, and various modifications can be made without departing from the scope of the present invention. is there.

[0030]

As described above, the first aspect of the present invention is as described above.
According to the described compression pressure release type engine auxiliary braking device, the accumulator internal pressure can be constantly maintained at a high pressure and constant, and the excellent effect that the response can be improved to improve the engine braking force can be achieved. Claim 2 of the present invention
According to the described compression pressure release type engine auxiliary braking device, without specially installing a dedicated accumulator,
The common rail of the engine, which is always kept at high pressure and constant, can be used as an accumulator, and the excellent effect that the response can be improved and the engine braking force can be improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration cross-sectional view of an example of an embodiment of the present invention.

FIG. 2 is a schematic structural cross-sectional view of another example of the embodiment for carrying out the present invention.

FIG. 3 is a schematic configuration diagram of a general compression pressure release type engine auxiliary braking device.

FIG. 4 is a cross-sectional view showing an example of a specific structure of a conventionally known compression pressure release type engine auxiliary braking device, showing a state in which a solenoid valve is opened by an auxiliary braking operation signal.

5 is a cross-sectional view showing a state in which the exhaust valve is opened by the operation of the slave piston from the state shown in FIG.

FIG. 6 is a cross-sectional view showing a state where the output of the auxiliary brake actuation signal is stopped and the solenoid valve is closed in the compression pressure release type engine auxiliary braking device shown in FIGS. 4 and 5.

FIG. 7 is a diagram showing a hydraulic pressure in an operating oil passage in the vicinity of a piston compression top dead center.

FIG. 8 is a cross-sectional view showing an example of a specific structure of a compression pressure release type engine auxiliary brake device equipped with an accumulator, and a cross-sectional view showing a state where a solenoid valve is opened by an auxiliary brake actuation signal.

FIG. 9 is a cross-sectional view showing an example of a specific structure of a compression pressure release type engine auxiliary brake device equipped with an accumulator, in which the accumulator internal pressure is increased after a solenoid valve is opened by an auxiliary brake operation signal. FIG.

10 is a sectional view showing a state in which the trigger valve is opened from the state shown in FIG. 9 and the exhaust valve is opened by the operation of the slave piston.

FIG. 11 is a compression pressure release type engine auxiliary braking device including the accumulator shown in FIGS. 8 to 10,
It is a sectional view showing the state where the output of the auxiliary brake actuation signal was stopped and the solenoid valve was closed.

[Explanation of symbols]

 1 Compressed pressure release type engine auxiliary brake device 7 Auxiliary brake controller 8 Auxiliary brake operation signal line 9 Piston 10 Exhaust valve 11 Solenoid valve 12 Control valve 14 Operation oil passage 16 Master piston 17 Rocker arm 21 Slave piston 23 Charge valve 24 Accumulator 25 Delay Piston 26 Trigger valve 27 Common rail 28 Pressure regulating piston

Claims (2)

[Claims] 1. A solenoid valve which is opened and closed by an auxiliary brake operation signal output from an auxiliary brake controller via an auxiliary brake operation signal line, and which supplies and shuts off engine oil, and an engine from the solenoid valve via a control valve. An operating oil passage to which oil is supplied, an accumulator to which engine oil is supplied from the operating oil passage via a charge valve and stores oil pressure, a master piston driven by a rocker arm, and a master piston driven by the master piston. A trigger valve for guiding the accumulator internal pressure transmitted through the delay piston to the working oil passage, and a slave piston which is driven by the hydraulic pressure in the working oil passage generated by the operation of the trigger valve and opens the exhaust valve. This is a compression pressure release type engine auxiliary braking device that uses the hydraulic pressure stored in the accumulator to drive the slave piston by the operation of the trigger valve and open the exhaust valve near the compression top dead center of the piston. An accumulator is connected to a common rail that is supplied with high-pressure fuel from a supply pump and guides the high-pressure fuel to an injector, via a pressure-adjusting piston capable of transmitting only pressure so that the internal pressure of the accumulator is kept constant by the internal pressure of the common rail. A compression pressure release type engine auxiliary braking device characterized in that 2. A solenoid valve which is opened and closed by an auxiliary brake operation signal output from an auxiliary brake controller via an auxiliary brake operation signal line, and which supplies and shuts off engine oil, and an engine from the solenoid valve via a control valve. An operating oil passage to which oil is supplied, a pressure adjusting piston which is connected to a common rail to which high pressure fuel is supplied from a high pressure supply pump and guides the high pressure fuel to an injector, and which can transmit only pressure, and a master driven by a rocker arm. A piston, a trigger valve driven by the master piston and guiding the common rail internal pressure transmitted through the pressure adjusting piston and the delay piston to the working oil passage, and working oil generated by the operation of the trigger valve Driven by hydraulic pressure in the passage It is equipped with a slave piston that opens the exhaust valve, and is configured to open the exhaust valve near the compression top dead center of the piston by using the internal pressure of the common rail to drive the slave piston by the operation of the trigger valve. Compressed pressure release type engine auxiliary braking device.