JPH037527Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a valve train using a hydraulic lifter applied to an internal combustion engine with an exhaust brake device.

<Prior Art> Some overhead valve type internal combustion engines employ a hydraulic lifter as a means for absorbing shocks in the valve train due to valve clearance (see, for example, Japanese Patent Publication No. 54-33324).

The operation of such a hydraulic lifter will be explained using, for example, FIG. The oil flows into the oil reservoir 6 in the plunger 4 through the oil hole 5, and further into the oil chamber 8 through the check valve 7, thereby lifting the plunger 4 and push rod seat 9 together and pushing up the push rod 10.

On the other hand, when an upward force is applied by the cam in contact with the bottom surface of the body 2, the hydraulic oil in the oil chamber 8 tries to flow backwards, but this is blocked by the check valve 7, so the body 2 and the plunger 4 are integrated and move upward. be pushed up. Therefore, in a valve train that employs a hydraulic lifter, the valve clearance can always be adjusted to zero.

<Problems to be solved by the invention> However, when such a valve train is applied to an internal combustion engine equipped with an exhaust brake, the pressure in the exhaust manifold increases when the exhaust brake is activated, causing the exhaust valve of the cylinder in the first half of the compression stroke to rise. The valve may open abnormally. In this case, the plunger 4 of the hydraulic lifter 1 will rise by an amount corresponding to the lift operation of the valve. As a result, the amount of lift of the exhaust valve increases in appearance, leading to the problem that the pressure inside the cylinder does not rise during the compression stroke, and the possibility that the exhaust valve and the top of the piston may interfere with each other at the top dead center of the piston. .

The prior art related to the present invention is Utility Application No. 59-38139 (Sho 60-
There is one proposed in Publication No. 152006).

This idea was made in view of the above circumstances.
The purpose is to stop the valve clearance adjustment function of the hydraulic lifter when the exhaust valve opens abnormally due to the operation of the exhaust brake.

<Means for solving the problem> Therefore, in the present invention, the engine exhaust system has an exhaust brake device, and a rocker arm is installed on the top surface of the intake and exhaust valves that are normally biased in the valve closing direction by the valve spring. Detecting means for detecting operation of an exhaust brake device in an internal combustion engine equipped with a valve operating device having one end in contact with the rocker arm and a hydraulic lifter for valve clearance adjustment connected to the other end of the rocker arm via a push rod; A pressure reducing means is provided for reducing the pressure of the hydraulic lifter of the exhaust valve system when the means detects the operation of the exhaust brake device.

<Function> As a result, the hydraulic pressure of the hydraulic lifter in the exhaust valve system is reduced in synchronization with the exhaust brake operation, the body of the hydraulic lifter and the plunger are able to move relative to each other, and the valve clearance adjustment function is stopped. I made it.

<Example> Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is an overall configuration diagram of an exhaust system valve mechanism showing one embodiment of the present invention.

In the figure, a cam 2 is installed on a camshaft 21 that rotates in synchronization with the engine crankshaft.
The lower end of a hydraulic lifter 30 applied to the exhaust valve system is in contact with the cam surface of No. 2. This hydraulic lifter 3
0 is slidably inserted into the guide hole 23 of the engine body.

The structure of the hydraulic lifter 30 is shown in FIG. 2 and will be explained.

This hydraulic lifter 30 has a plunger 3 slidably disposed within a body 31 that comes into contact with the cam surface of the cam 22.
2 and a push rod seat 33 are provided. A piston 34 is slidably provided within the plunger 32, and the piston 34 is elastically biased downward in the figure by a spring 35.
The first oil chamber 36 defined by the piston 34 and the plunger 32 contains the body 31 and the plunger 3.
Hydraulic oil (for example, engine oil) is supplied through the oil holes 31a and 32a formed in the piston 34 and the oil hole 32a of the plunger 32. 32b and a check valve 37, the oil can flow into a second oil chamber 38 defined by the body 31 and the plunger 32. Inside the second oil chamber 38 is a spring 3 that elastically urges the plunger 32 upward in the figure.
9 is interposed.

Therefore, in this hydraulic lifter 30, the first oil chamber 3
6, the piston 34 is moved upward against the elastic force of the spring 35, and the check valve 37 is pushed down to open the second oil chamber 38.
When hydraulic oil can flow into the exhaust valve and no force is applied from the exhaust valve side, the plunger 32 is pushed up, but when an upward force is received from the cam 22, the check valve 37 prevents the oil from returning and the body 31 and plunger 32 are pushed upward together and perform a normal operation.

On the other hand, when the oil pressure in the first oil chamber 36 is low,
The piston 34 is pushed down by the spring 35,
The check valve 37 is kept open at all times by its tip. As a result, the first oil chamber 36 and the second oil chamber 38 are in constant communication, and even if force is applied to the hydraulic lifter 30 from the outside, only the oil within the hydraulic lifter 30 moves, and the hydraulic lifter 30 itself There is no movement and it is in an inactive state.

The upper end of a push rod 41 seated on the push rod seat 33 of the hydraulic lifter 30 is connected to one end of a rocker arm 43 via an adjusting screw 42. This Rotsuka arm 43
is pivotally supported by a rocker shaft 45 which is rotatably supported by a rocker bracket 44, and the other end is in contact with the top surface of the valve stem of the exhaust valve 46. 47 is a valve guide, 48 is a valve spring that is interposed between the cylinder head 49 and the retainer 50 and always biases the exhaust valve 46 in the closing direction, and 51 is an exhaust port.

Next, the configuration of the exhaust brake device of this embodiment will be explained.

The battery 61 includes a manual exhaust brake switch 62 that is turned on and off by the passenger's operation, a clutch switch 63 that is turned off when the clutch pedal is pressed and turned on when released, and a clutch switch 63 that is turned off when the accelerator pedal is pressed and turned on when released. A series circuit consisting of an accelerator switch 64 and a magnetic valve 65 for opening and closing the exhaust brake shutter is connected in series. The magnetic valve 65 is connected to an air cylinder 68 for driving an exhaust brake shutter 67 installed in an exhaust passage 66.
The air passage 70 connects the air cylinder 68 and the air reservoir 69 when energized, and connects the air cylinder 68 and the air reservoir 69 when energized.
8 side and the atmosphere. 71 is a pilot lamp for indicating the operation of the exhaust brake.

On the other hand, the oil supply gear gallery 24 for supplying hydraulic oil to the hydraulic lifter 30 includes a branch passage 24A connected to the hydraulic lifter 30 of the exhaust valve system of each cylinder,
A branch passage 24B connected to a hydraulic lifter 80 applied to the intake valve system shown in FIG. 3 is provided, and oil in an oil pan 26 is supplied by an oil pump 25. In addition, the refueling gear 24
An electromagnetic pressure regulating valve 27 is installed as a pressure reducing means. The pressure regulating valve 27 is energized when the exhaust brake switch 63 is on, and opens its relief passage 28 to the oil supply gear 24 to release the hydraulic oil in the oil supply gear 24 to the oil pan 26 and reduce the oil pressure therein.

Next, the intake valve system hydraulic lifter is shown in FIG. 3 and will be described.

This is a commonly used type of hydraulic lifter, in which a plunger 82 and a push rod seat 83 are slidably provided in a body 81, and an oil hole 81a in the body 81 and an oil hole 82 in the plunger 82 are provided.
A first oil chamber 84 in the plunger 82 into which hydraulic oil flows through a is communicated with a second oil chamber 86 through a check valve 85. A spring 87 elastically urges the plunger 82 and the push rod seat 83 upward.

In the case of such a hydraulic lifter 80, the plunger 8
Its function is always maintained regardless of the level of oil pressure of the hydraulic oil supplied to the first oil chamber 84 in the second oil chamber 84.

Next, the effect will be explained.

When the clutch pedal and the accelerator pedal are released, the clutch switch 63 and the accelerator switch 64 are turned on, and in this state, the exhaust brake switch 6 is turned on.
2, an energizing circuit is formed from the battery 61 to the magnetic valve 65, and the magnetic valve 65 is energized. As a result, compressed air is supplied from the air reservoir 69 to the air cylinder 68 via the air passage 70, the exhaust brake shutter 67 closes the exhaust passage 66, and the exhaust brake is activated.

When the exhaust brake is activated, the electromagnetic pressure regulating valve 27 is also energized in synchronization with the ON operation of the exhaust brake switch 62, and the relief passage 28 is opened, so that a part of the hydraulic oil in the oil supply gear 24 is transferred from the relief passage 28 to the oil pan. Relief within 26. As a result, from the oil supply gear gallery 24 to each branch passage 24
The hydraulic pressure supplied to each hydraulic lifter 30, 80 via A, 24B is reduced. Then, as described above, the intake valve system hydraulic lifter 80 maintains its function, but the exhaust valve system hydraulic lifter 30 stops its function and becomes inoperative.
Therefore, when the exhaust brake is activated, the exhaust valve 4
Even if an abnormal valve opening occurs, there is no fear that the hydraulic lifter will lift like in the past.
As the exhaust pressure decreases, the exhaust valve 46 closes.

On the other hand, when the exhaust brake switch 62 is turned off to release the exhaust brake, the electromagnetic pressure regulating valve 27 is demagnetized, the relief passage 28 is closed, and the oil pressure in the oil supply gear 24 is returned to its normal value. Therefore, both hydraulic lifters 30 and 80 return to their operating states, and the opening and closing operations of the intake and exhaust valves are performed.

In this embodiment, a hydraulic lifter of a different type from that of the intake valve system is used as the hydraulic lifter of the exhaust valve system, but a hydraulic lifter of the same type as that of the intake valve system can also be used. In this case, an oil hole is formed in the body 81 of the hydraulic lifter 80 through which the hydraulic oil in the second hydraulic chamber 86 can be discharged, and the oil hole and the oil pan are communicated with each other, and an exhaust brake activation signal is provided in the communication path. A passage opening/closing valve that opens when the exhaust brake is operated may be installed to release the hydraulic pressure in the second oil chamber 86 when the exhaust brake is operated, and the same effects as in this embodiment can be obtained.

<Effects of the invention> As described above, according to the invention, when the exhaust brake is activated, the hydraulic lifter of the exhaust valve system becomes inactive and the valve clearance correction function is stopped, thereby preventing abnormal opening of the exhaust valve. Sometimes the hydraulic lifter does not follow this, and the maximum lift position of the exhaust valve does not fall downward, causing problems such as the cylinder pressure not rising during the compression stroke, and problems such as interference between the exhaust valve and the piston at the top dead center of the piston. can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention;
Fig. 2 is a block diagram of a hydraulic lifter applied to the exhaust valve system of the same embodiment as above, Fig. 3 is a block diagram of a hydraulic lifter similarly applied to the intake valve system, and Fig. 4 explains the operation of a conventional hydraulic lifter. This is a diagram for 22...Cam, 24...Lubrication gear, 27...
...Solenoid pressure regulating valve, 28...Relief passage, 30...
Hydraulic lifter, 41... Push rod, 43...
Locker arm, 46...Exhaust valve, 62...Exhaust brake switch, 65...Magnetic valve, 67...Exhaust shutter, 68...Air cylinder, 69...Air reservoir.

Claims (1)

[Scope of utility model registration request] The engine exhaust system has an exhaust brake device, and one end of the rocker arm is brought into contact with the top surface of the intake/exhaust valve, which is always biased in the closing direction by a valve spring, and the valve clearance is applied to the other end of the rocker arm via a push rod. In an internal combustion engine equipped with a valve train connected to a hydraulic lifter for adjustment, there is a detection means for detecting operation of the exhaust brake system, and when the detection means detects operation of the exhaust brake system, the exhaust valve system A valve train for an internal combustion engine, comprising a pressure reducing means for reducing the hydraulic pressure of the hydraulic lifter.