JPH057475Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine braking device for automobiles, and more particularly, to an engine braking device using an exhaust brake.

(Prior art) In large vehicles such as trucks and buses, if only the service brake is operated on long slopes, there will be significant fade and, in some cases, problems such as mechanical weakening of the lining and pads may occur. In addition to the automobile brake itself, it is known that braking is performed by the engine itself.

As a device that performs braking of the engine itself, for example, in addition to the normal exhaust passage that communicates with the combustion chamber during the exhaust stroke of the engine, another exhaust port is formed and this exhaust port is opened and closed. There is an exhaust brake equipped with an exhaust valve.

In this exhaust brake, when the piston is at the top dead center position, that is, in the combustion chamber where the stroke phase of the crank is near the top dead center of the compression stroke, the exhaust valve of the exhaust port is opened to blow out the compressed air in the combustion chamber. By absorbing the compression work and introducing a part of this compressed air through the exhaust port of the combustion chamber near the bottom dead center of the intake stroke to increase the compression work when moving to the compression stroke, the brake It is designed to make the force sufficiently high.

Now, an example of the above-mentioned exhaust brake will be explained in the drawings as follows.

FIG. 3 shows the structure in a normal state, that is, in a state in which the exhaust brake is not activated.

In addition, in the figure, another exhaust port is provided in the combustion chamber in addition to the normal intake/exhaust port, and an exhaust opening/closing valve (hereinafter referred to as A case in which a third valve (referred to as a third valve) is provided is shown.

In the figure, reference numeral 1 indicates a cylinder, reference numeral 1A indicates a combustion chamber, reference numeral 3 indicates a third valve, and reference numeral 4 indicates another exhaust port.

The third valve 3 is a normally closed valve that is given a predetermined load by a spring 5, and has a piston 6 at the upper end of the stem. It is inserted.

A relief valve 9 is attached to the upper part of the cylinder part 8, and an oil passage 11 extending from an operating part 10, which will be described later, is connected to the side of the cylinder part 8.

The actuating unit 10 serves as a supply and discharge unit for hydraulic oil for opening and closing the third valve, and is a part that constitutes a drive hydraulic pressure generation system when supplied, and includes an intake/exhaust valve drive cam (not shown). ) rotates in response to
A valve driving cam 100, a cylinder portion 101 formed in the actuating portion main body, and a spring 10 that is slidably inserted into the cylinder portion 101.
2, and a piston 103 whose head is given a movement behavior in the direction of pressing against the circumferential surface of the third valve driving cam 100, and the cylinder part 101
An oil reservoir 101a is formed in a part of the oil passage 11 and a hydraulic oil supply oil passage 12 communicating with a control valve 20, which will be described later, is connected.

The port of the oil sump 101a to which the above-mentioned oil passage is connected is a position for outputting hydraulic oil to the third valve 3, and the port of the oil sump 101a to which the hydraulic oil supply passage 12 is connected is Control valve 20 described later
The piston 103 is located at a position where hydraulic oil is input from the piston 103, and the hydraulic oil can be sucked and discharged according to the displacement of the plunger 103a driven by the piston 103.

The control valve 20 is for selecting a first position in which hydraulic oil is supplied to the operating part 10 and a second position in which hydraulic oil is recovered from the operating part 10.
01 and a piston 202 that can slide inside the oil chamber 201.
It is made up of.

The oil chamber 201 has oil reservoirs 201A and 201B at both ends in the sliding direction of the piston 202, and one oil reservoir 201A has a recovery oil passage 13 forming a hydraulic oil recovery system and an operating section extending to the operating section 10. The oil supply oil passages 12 are in communication with each other, and the other oil reservoir 201B is connected to a pressure oil input oil passage 14 forming a hydraulic input system for supplying piston drive oil.

Inside the piston 202, there is another oil reservoir 20.
An oil passage 202B1 communicating with the oil passage 202B1 is formed in a part of this oil passage 202B1, and a check valve 203 which is normally provided with a habit of closing the oil passage 202B1 by a spring (not shown) is provided. There is.

A circumferential groove 202B2 that opens in the circumferential wall of the piston 202 is formed at the end of the oil passage 202B1 past the check valve 203.

A spring 204 disposed in one oil reservoir 201A of the oil chamber 201 allows the piston 202 to be continuously connected to the hydraulic oil supply passage 12 from the operating section 10.
and the recovery oil passage 13 are held in a second position in communication with each other.

A pressure source 1 is connected to the pressure oil input oil passage 14 of the pressure oil input system connected to the other oil reservoir 201B of the oil chamber 201.
5 is connected to an oil gear rally 16 having a distribution function, and when hydraulic oil from the other oil reservoir 201B of the oil chamber 201 is supplied from this oil gear rally 16, the piston 202 moves against the bias of the spring 204. As shown in FIG. 4, it moves to the left and opens the check valve 203, so that the circumferential groove 202B2 and the hydraulic oil supply passage 12 communicate with each other.

In such a configuration, when both the exhaust brake switch and the accelerator pedal return detection switch (not shown) are operated, as shown in FIG. The other oil sump 20
Hydraulic oil is supplied to 1B.

Therefore, in the control section 20, the other oil chamber 2
When the pressure in the oil passage 202B1 increases and the check valve 203 is opened, the oil passage 202B1 and the circumferential groove 202B2 are also filled with oil, and in this state, the other oil Room 201
When the pressure of B is increased, the piston 202 slides toward the left in the figure against the bias of the spring 204, thereby increasing the pressure through the communication between the circumferential groove 202B2 and the hydraulic oil supply passage 12. A first position is set in which the pressure oil input oil passage 14 and the hydraulic oil supply oil passage 12 communicate with each other to supply hydraulic oil to the operating section 10 .

Moreover, when the pressure increases due to the filling of the hydraulic oil supply oil passage 12 with oil, the oil reservoir 101 in the actuating part 10
Oil also spreads to the oil passage 11 via the oil reservoir 101a and the oil reservoir 101a.

In this state, the third valve cam 100 of the operating section 10
When the piston 10 rotates, its top edge
3 is pressed, the piston 103 slides against the bias of the spring 102 in a direction that reduces the volume inside the oil reservoir 101a.

Therefore, the pressure in the oil reservoir 101a is increased, increasing the pressure in the oil passage 11 and the hydraulic oil supply passage 12, but on the hydraulic oil supply passage 12 side, control is performed according to the increase in pressure. Since the flow of oil that is about to be pushed back toward the valve 20 side is blocked by the check valve 203, the pressure of the oil toward the oil path 11 side is increased and supplied into the cylinder 8, and the piston 6 is By being pushed down, the third valve 3
will be released.

On the other hand, if the exhaust brake is not activated,
Since the hydraulic oil supply from the pressure oil input oil passage 14 of the control valve 20 is released, the piston 202 communicates the hydraulic oil supply oil passage 12 and the recovery oil passage 13 by the bias of the spring 204, and the oil is removed. The oil in the passage 11 and the oil reservoir 101a of the operating part 10 is pushed back via the bias of the spring 5 on the third valve 3 side, thereby communicating the hydraulic oil supply passage 12 and the recovery oil passage 13. The hydraulic oil from the operating part 10 is transferred to the oil pan 17.
It is now possible to set a second position for recovery.

(Problems to be Solved by the Invention) In the above-described exhaust brake device, when the operation of the exhaust brake is stopped, the piston 202 of the control valve 20 is biased by the spring 204.
The hydraulic oil supply passage 12 and the recovery oil passage 13 are returned to the second position in communication with each other, whereby the oil in the oil passages 11 and 12 is recovered to the oil pan 17 via the recovery oil passage 13. I'm starting to do that.

However, when recovering such oil, the oil line 11
As the hydraulic oil supply oil passage 12 and oil recovery passage 13 communicate with each other, the resistance force that blocks the flow of oil in the oil recovery system disappears, so that it acts to close the third valve side 3. An inertial force is generated in the oil by the biasing force of the spring 5, and this inertial force may cause some oil to flow even at the moment the third valve 3 is closed. The surface may drop, creating an air pocket above the liquid level.

The air pocket due to the drop in the liquid level mentioned above tends to have a negative pressure, so air tends to enter through gaps in the piston's sliding part, and the air pocket expands or air gets mixed into the hydraulic oil. become.

Therefore, when the exhaust brake is operated again, each oil passage and the third valve 3 side are filled with oil slowly, which may lead to malfunction or poor response of the exhaust brake.

Therefore, in view of the above-mentioned problems with conventional exhaust brake devices, the purpose of the present invention is to provide a structure that can prevent air from entering the oil passage or into the oil, thereby preventing malfunction and poor response. The object of the present invention is to obtain an exhaust brake device.

(Means for solving the problem) In order to achieve this objective, an exhaust opening/closing valve that can open the exhaust port of the combustion chamber whose stroke phase is near the top dead center of the compression stroke is provided, and the compressed air in the compression stroke is is discharged from the exhaust port to absorb the compression work in the combustion chamber, and a part of the discharged air is introduced through the exhaust opening/closing valve of the combustion chamber located near the bottom dead center of the intake stroke. In an engine braking device that increases the braking force by increasing the air filling amount in the combustion chamber and increasing the amount of compression work, a hydraulic oil supply/discharge unit for opening and closing the exhaust opening/closing valve. an operating section that has a hydraulic oil input section and a hydraulic oil output section, each forming a hydraulic oil input section and a hydraulic oil output section, and selects a position for supplying hydraulic oil for operating the exhaust valve and a position for recovering the hydraulic oil; A hydraulic oil supply line connected to the hydraulic oil input part of the operating section, a pressure oil input line from the hydraulic source, and a recovery oil line for recovering the pressure oil discharged from the operating section are connected, and the hydraulic oil is a control unit that selects a first position in which the supply oil passage and the pressure oil input oil passage communicate with each other and a second position in which the hydraulic oil supply passage and the recovery oil passage communicate with each other; An input port communicating with a second pressure oil input oil passage branched from the oil input oil passage, a first discharge port communicating with a first discharge oil passage branching from the recovery oil passage, and an oil pan. A second discharge port is provided which communicates with a second recovery oil passage, and an operating pressure that closes the input port and communicates the first discharge port and the second discharge port to set the first position in the control section. Direction switching that allows selection of a supply position and an operating pressure release position in which the second discharge port is closed and the input port and the first discharge port are communicated to set a second position in the control unit. and a control section, the direction switching control section comprising:
When the engine brake operation is stopped, the operating pressure release state is set, the input port and the first discharge port are communicated, and the oil pushed out from the control section is transferred from the first discharge port into the recovery oil path. It is characterized by the introduction of

According to the present invention, when the exhaust brake device is not activated, pressure oil is stored in the oil chamber where the hydraulic oil supply passage and the recovery oil passage communicate with each other when the second position is set in the control section. Hydraulic oil from the input oil passage is introduced, and the flow of oil from the hydraulic oil supply passage to the recovery oil passage is blocked.

(Embodiment) Hereinafter, details of an embodiment of the present invention will be explained with reference to FIGS. 1 and 2.

In FIGS. 1 and 2, the same components as those shown in FIGS. 3 and 4 are designated by the same reference numerals.

In FIG. 1, a second pressure oil input oil passage 21 consisting of a branch pipe communicates with the oil gear rally 16, and a directional control valve 22 consisting of a solenoid valve is connected to the second pressure oil input oil passage 21. Input support 22a
is connected.

The direction switching control valve 22 has an operating pressure supply position and a control unit 2 for setting the first position of the control valve 20.
This is a directional control valve that allows selection of the operating pressure release position for setting the second position at 0, and in addition to the input port 22a described above, the first discharge port 2
2b and a second discharge port 22c.
2A is provided.

The first discharge port 22b communicates with a first discharge oil passage 24, and this first discharge oil passage 24 is a sub-tube that is disposed in the recovery oil passage 13 from the control valve 20 and forms a hydraulic oil recovery system. It is connected to the oil gear gallery 23.

Further, the second discharge port 22c is connected to the oil pan 1.
7 and communicates with the second recovery oil passage 25.

The solenoid of the directional control valve 22 is equipped with a check valve 220 made of a spherical body, and has an input port 22a side and a second discharge port 22c.
It is designed to connect with the side. This solenoid has a permanent life, that is, as shown in Figure 1,
When the piston 202 of the control valve 20 is set to the second position that communicates the hydraulic oil supply path 12 and the recovery oil path 13, it has a habit of blocking the second discharge port 22c side. .

In this state, the first
Hydraulic oil from the oil gear rally 16 is forced toward the discharge oil path 24, and then flows into the recovery oil path 13 via the sub-oil gear gallery 23, and reaches the oil reservoir 201A on one side of the control valve 20. The operating pressure is released.

Further, the timing disc at which the solenoid can switch its position is when the exhaust brake is activated, and at this point, the direction change control valve 22
The input port 22a of is cut off.

Therefore, in this state, as shown in FIG.
1B, the first discharge port 22b and the second discharge port 22c are set to communicate with each other, and as the piston 202 is pushed and moved, one of the oils in the control valve 20 is room 20
Hydraulic oil pushed out from inside 1A flows from the second discharge port 22c of the directional control valve 22 to the second recovery oil path 25 via the recovery oil path 13 and the sub-oil gear gallery 23.

In this embodiment, the operating pressure is supplied to set the first position of the control valve 20 when the exhaust brake is activated and the position of the solenoid in the direction switching control valve 22 is switched. It is considered a posture.

Since this embodiment has the above-described configuration, the state in which the exhaust brake is activated is as shown in FIG. 2.

That is, in the directional control valve 22, the solenoid closes the input port 22a and closes the first discharge port 22a.
A working pressure supply position is set in which the working oil from the oil reservoir 201A on one side of the control valve 20 is discharged by communicating between the oil reservoir 201A and the second discharge port 22c.

When this position is set, the hydraulic oil from the sub-gear rally 16 is supplied to the other oil chamber 201B of the control valve 20, filling the oil passage 202B1 and the circumferential groove 202B2 in the piston 202, and
02 is pushed and moved to connect the circumferential groove 202B2 and the working pressure supply oil passage 12, and here the first position of the control valve 20 where the pressure oil input oil passage 14 and the working pressure supply oil passage 12 communicate with each other. will be set.

Further, while the first position is set, the hydraulic oil pushed out from the oil chamber 201A of the control valve 20 as the piston 202 is pushed is transferred to the sub oil gear gallery 23 and the oil chamber 201A of the control valve 20. The oil is introduced into the direction switching control valve 22 via the first discharge oil passage 24, and is recovered into the oil pan 17 from the second recovery oil passage 25 via the first discharge port 22b and the second discharge port 22c.

Therefore, when the third valve driving cam 100 rotates and the piston 103 in the actuating section 10 is pushed and moved when the first position is set, the oil sump 10
The hydraulic oil in 1a is pressurized and introduced into the cylinder 8 through the oil passage 11, increasing the pressure in the cylinder 8 and opening the third valve 3. The operating position of the third valve 3 at this time is the same as that shown in FIG.

On the other hand, when the operation of the exhaust brake is stopped and the solenoid of the directional control valve 22 returns to the normal position, the second discharge port 22c of the directional control valve 22 is closed as shown in FIG. An operating pressure release position is set in which the port 22a and the first discharge port 22b communicate with each other.

When this position is set, the oil gear rally 16
The hydraulic oil is introduced into the input port 22a of the directional control valve 22, flows into the first discharge oil passage 24 via the first discharge port 22b, and is supplied to the recovery oil passage 13 by the sub-oil gear gallery 23. One oil chamber 20 of the control valve 20 is
1A.

Therefore, when the exhaust brake is deactivated,
The directional control valve 22 outputs the hydraulic oil from the oil gear 16, including the hydraulic oil pushed out from the other oil chamber 201B of the control valve 20, to the first discharge port 22.
b, the oil is introduced into one oil chamber 201A of the control valve 20 via the recovery oil passage 13 and the first discharge oil passage 24.

As a result, in the control valve 20, one oil chamber 20
1A is filled with hydraulic oil and the spring 204 is biased, the piston 202 is moved to the right as shown in the first diagram, and the hydraulic pressure supply oil passage 12 and recovery oil are connected to one oil chamber 201A. By communicating with the passage 13, the hydraulic oil is prevented from returning from the working pressure supply oil passage 12 and the oil passage 11, and a state in which the pressure does not decrease is maintained.

In this embodiment, a case has been described in which a third valve is provided separately from the normally used intake/exhaust valve, but the invention is not limited to this, and the normally used exhaust valve can also be used as the third valve to control the opening/closing timing. It may be set according to the operating position of the exhaust brake.

(Effects of the invention) As described above, according to the invention, when the operation of the exhaust brake is stopped, the hydraulic oil that is forced to open and close the exhaust valve is directed toward the oil pan to prevent it from being collected. Since the flow direction can be controlled, when the exhaust brake operation is stopped, it is possible to prevent the drop in the liquid level that occurs during oil recovery and to suppress air intrusion. Defects and response failures can be prevented.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing the structure and operation of an embodiment of the present invention, and FIGS. 3 and 4 are schematic diagrams showing the structure and operation of a conventional engine braking device, respectively. 1... Cylinder, 1A... Combustion chamber, 3... Exhaust on/off valve, 10... Actuating part, 100... Cam, 10
1a...Oil sump, 103...Piston, 11...
Oil passage, 12... Hydraulic oil supply oil passage, 13... Recovery oil passage, 14... Pressure oil input oil passage, 16... Oil gear rally, 17... Oil pan, 20... Control valve, 2
DESCRIPTION OF SYMBOLS 1...Second pressure oil input oil passage, 22...Directional switching control valve, 22a...Input port, 22b...First discharge port, 22c...Second discharge port, 23...Sub gear rally, 24...First 1 discharge oil path, 25...second recovery oil path.

Claims (1)

[Scope of Claim for Utility Model Registration] An exhaust opening/closing valve capable of opening an exhaust port of a combustion chamber whose stroke phase is near the top dead center of the compression stroke is provided, and the compressed air in the compression stroke is discharged from the exhaust port. Therefore, the compression work in the combustion chamber is absorbed, and a part of the exhaust air is introduced into the combustion chamber through the exhaust valve located near the bottom dead center of the intake stroke. In an engine braking device that increases the braking force by increasing the air filling amount and compression work, the engine brake system includes a hydraulic oil input section and a hydraulic oil supply section that supply and discharge hydraulic oil for opening and closing the exhaust on-off valve. an operating section each having an output section and in which a position for supplying hydraulic oil for operating the exhaust valve and a position for recovering the hydraulic oil are selected; and a hydraulic oil input section of the operating section connected to the operating section. The hydraulic oil supply passage, the pressure oil input oil passage from the hydraulic source, and the recovery oil passage for recovering the pressure oil discharged from the operating part are connected, and the hydraulic oil supply passage and the pressure oil input oil passage are connected to each other. a control unit that selects a first position in which the hydraulic oil supply passage and the recovery oil passage communicate with each other, and a second position in which the hydraulic oil supply passage and the recovery oil passage are connected; an input port that communicates with the two-pressure oil input oil passage, a first discharge port that communicates with a first discharge oil passage branched from the recovery oil passage, and a second recovery oil passage that communicates with the oil pan. an operating pressure supply position including two discharge ports, closing the input port and communicating the first discharge port and the second discharge port to set a first position in the control unit; and the second discharge port. a direction switching control unit capable of selecting an operating pressure release position in which the port is closed and the input port and the first discharge port communicate with each other to set a second position in the control unit; When the operation of the engine brake is stopped, the control unit is configured to set the operating pressure release position and communicate the input port and the first discharge port;
An engine braking device characterized in that oil pushed out from a control section is introduced into the recovery oil path from a first discharge port.