JPH09287427A - Engine brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To switch operation with good responsiveness by providing with an operation switching valve for switching control oil pressure so as to operate or non-operate a brake unit for releasing compressed pressure at the time of an engine brake, and constituting the valve by a flow rate control spool valve and a switch spool valve. SOLUTION: In this case where engine brake force is increased, current is fed to the driving solenoid 83 of an operation switching valve 2 by a microcomputer 5 when an operation switch 4 is turned on, the valve rod of a switching spool valve 62 is raised, and the valve element of a flow rate control spool valve 61 is pushed down. On time control oil pressure corresponding to gallery pressure is supplied to the oil taking-in part 19 of a brake unit 1 by an oil pipe 3. A switching piston is retreated by control oil pressure, a switching pin is separated from the ball of check valve 10, and engine oil flows into a high oil pressure chamber 21. A release piston 8 is pushed down by its oil pressure, an exhaust valve 6 just before closing a valve is slightly opened, and brake effective pressure is exhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine braking device for releasing a compression pressure in a cylinder to increase an engine braking force.

[0002]

2. Description of the Related Art Recently, various engine brake devices have been proposed which increase the engine braking force by lifting an exhaust valve or a dedicated valve to release the compression pressure in a cylinder when the engine brake is used. There is. Of these, the normally open type engine brake device keeps the valve in a slightly lifted position when the braking force needs to be increased so that the compression pressure is released from the cylinder over the entire cycle. .

[0003]

By the way, in order to activate or deactivate the engine brake device, it is conceivable to control the supply of the operating oil pressure by a switching valve. However, if the switching valve is simply turned on and off to turn it on and off, air mixes into the hydraulic circuit of the brake unit, causing a problem in responsiveness and the like. In order to prevent this, switching valves for ON and OFF are provided respectively so that air is not mixed by constantly supplying the control oil pressure.
The entire device becomes large, leading to weight increase and cost increase. In addition, in an engine braking device that has a cylinder with a dedicated valve for releasing exhaust gas, a configuration has been proposed in which the control hydraulic pressure is switched by an air-driven control valve, but this system should be used for vehicles that do not have an air compressor. I can't.

[0004]

SUMMARY OF THE INVENTION To solve the above problems, the present invention provides a brake unit that operates by control hydraulic pressure to release a compression pressure during engine braking, and a control hydraulic pressure that activates or deactivates the brake unit. An engine braking device having an operation switching valve for switching,
The operation switching valve selectively controls the amount of oil from the control oil pressure supply source to supply the control oil pressure for operation or non-operation to the brake unit, and the control oil pressure for the first valve means. And a second valve means that is appropriately driven by the hydraulic pressure of the supply source. The first valve means preferably has a pressure holding mechanism for keeping the control hydraulic pressure constant.
The second valve means is preferably driven by a controller for controlling the operation of the brake unit according to the engine operating condition and the like. With this configuration, the first valve means driven by the second valve means determines the amount of oil from the control hydraulic pressure supply source, and supplies the control hydraulic pressure when ON to the brake unit. The control unit operates the brake unit to release the compression pressure of the cylinder and increase the engine braking force. When the control oil pressure when the first valve means is OFF is supplied to the brake unit, the brake unit is deactivated and the normal engine operation is resumed.

[0005]

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

FIG. 1 shows a case where the engine braking device of the present invention is applied to a four-cylinder engine. This engine braking device operates with control hydraulic pressure to release a compression pressure during engine braking, and an operation switching valve 2 that switches the control hydraulic pressure between high and low in order to activate or deactivate the brake unit 1. It is mainly composed of and. Brake unit 1
Are provided in each cylinder (NO1, NO2, NO3, NO4 cyl.), And are collectively connected to one operation switching valve 2 by an oil pipe 3 for supplying control hydraulic pressure (engine oil). The operation switching valve 2 is connected so as to be operated by an operation switch 4 provided in a driver's seat and a microcomputer (CPU arithmetic processing unit) 5 which is a controller.
The operating condition of the engine such as the cooling water temperature and the engine speed is input to the input section of the microcomputer 5, and the ON / OFF operation of the operation switch 4 and the microcomputer 5 are performed.
The operation switching valve 2 is optimally operated based on the judgment of the operating state and the like. Further, the controller 5 is always "OFF" when the engine brake is not used, in other words, when the accelerator pedal is depressed.
It is configured so that In addition, in FIG. 1, the ON state and the OFF state of the operation switching valve 2 are shown together,
When the NO1 cylinder and NO3 cylinder are ON,
The cylinder and NO4 cylinder are shown in the OFF state, respectively.

The brake unit 1 includes a release piston 8 movably provided in a housing 7 arranged above the exhaust valve 6 and a hydraulic circuit 9 in the housing 7 so that a control hydraulic pressure acts on the release piston 8 as appropriate. The check valve 10 is provided. The exhaust valve 6 is an open end of the exhaust port 11 (valve seat 12) that faces the inside of the cylinder of the engine.
It is formed by a valve portion 6a which is seated on the valve portion 6a, and a valve shaft 6b which is attached to an axial center position of the valve portion 6a and extends upward. The exhaust valve shaft 6b is connected to one end of a rocker arm (not shown) via a valve bridge 13, and is in the valve closing direction (upward).
A return spring 14 for urging the valve is provided.
That is, the cam driven rocker arm lifts the pair of exhaust valves 6 at a predetermined timing during the exhaust stroke. As shown in FIG. 2, an intermediate shaft 26 that vertically penetrates the end portion of the valve bridge 13 is provided on the valve shaft 6b of one exhaust valve 6 and slides on a sleeve 15 provided on the valve bridge 13. It is supported freely. A flange 16 that engages with the lower surface of the sleeve 15 is formed at the lower end of the intermediate shaft 26.
When 6 is pushed downward, the exhaust valve 6 is lifted regardless of the operation of the rocker arm, and when the rocker arm is swung, it is integrated with the valve bridge 13 to push the exhaust valve 6. . The outer periphery of the sleeve 15 is threaded, and is screwed into a vertical through hole formed in the valve bridge 13.

As shown in FIG. 2, the brake unit 1
The housing 7 includes a vertical columnar portion 7a for accommodating the release piston 8 and a horizontal columnar portion 7b for accommodating the check valve 10. Horizontal columnar part 7b
A switching pin 17 for performing a switching operation of the check valve 10.
And a switching piston 18. The vertical columnar portion 7a is located directly above the exhaust valve 6, and the horizontal columnar portion 7b extends radially outward from the vertical columnar portion 7a. An oil intake portion 19 is provided below the vertical cylindrical portion 7a.
And an oil pipe 3 extending from the operation switching valve 2 is connected.

The release piston 8 is composed of a cylindrical piston head portion 8a and a rod portion 8b extending below the piston head portion 8a. The piston head 8a is formed so as to slide in a vertical cylinder 20 provided inside the housing vertical cylindrical portion 7a. That is, the space between the piston head 8a and the inner surface 20a of the upper wall of the cylinder 20 is defined as a high hydraulic chamber 21 for pushing down the release piston 8. The lower end of the cylinder 20 opens to the lower surface of the housing 7, and a piston stopper 23 having a flange 22 having a diameter larger than that of the opening is screwed. The upper end of the threaded portion of the piston stopper 23 comes into contact with the outer periphery of the lower surface of the piston head 8a, thereby defining the lower limit position of the release piston 8. A stopper bolt 24 is provided coaxially with the cylinder 20 on the upper wall of the vertical cylindrical portion 7a, and the lower end thereof projects slightly into the cylinder 20. That is, the piston head 8a contacts the lower end of the stopper bolt 24, thereby defining the upper limit of the release piston 8 and ensuring a space for the engine oil to flow into the high hydraulic chamber 21. A return spring 25 is provided between the inner periphery of the lower surface of the piston head 8a and the upper surface of the flange 22 of the piston stopper 23 to urge the release piston 8 upward. The release piston rod portion 8b extends downward through a shaft hole formed in the piston stopper 23, and its lower end is in contact with the upper end of the intermediate shaft 26. That is, when the release piston 8 descends until it comes into contact with the piston stopper 23, the exhaust valve 6 is opened by a predetermined minute amount L (see NO1 cylinder and NO3 cylinder in FIG. 1).

The hydraulic circuit 9 in the housing 7 extends horizontally from the high hydraulic chamber 21 into the horizontal cylindrical portion 7b. A housing hole 27 is formed in the horizontal cylindrical portion 7b, and a valve body 28 for forming the check valve 10 is fitted in the housing hole 27. As shown in FIG. 3, the valve body 28 is formed with a shaft hole 29 that substantially partitions the hydraulic circuit 9. The shaft hole 29
Are sequentially opened from one end side, the opening portion 30 facing the high hydraulic pressure chamber 21 side, the portion 31 reduced in diameter, the portion 32 slightly smaller in diameter than the opening portion 30, and the opening portion on the other end side. And a proximal portion 33. And the opening 3 on the high hydraulic chamber 21 side
The check valve 10 is provided at 0 and the switching piston 18 is provided at the base end portion 33. The check valve 10 includes a ball 34 having a diameter sufficiently larger than the small-diameter portion 31, a ball retainer 35 for holding the ball 34 at the opening 30, and a ball spring 36 provided inside the ball retainer 35. . The ball spring 36 presses the ball 34 against the inclined surface 31 a which is the end of the small diameter portion 31, and is formed so as to pass the engine oil only in the direction from the shaft hole 29 toward the high hydraulic pressure chamber 21. ing. The ball retainer 35 is a bottomed cylindrical member having an inner diameter larger than that of the ball 34, and has a base end attached to a corner of the opening 30. And, in the ball retainer 35,
A slit (not shown) is formed for communicating the high hydraulic chamber 21 and the shaft hole 29 when the ball 34 is pushed against the ball spring 36.

The switching pin 17 is composed of a right circular cylindrical portion 17a having an outer diameter smaller than that of the shaft hole small diameter portion 31 and a base portion 17b having a substantially truncated cone shape, and the base portion 17b is coaxially integrated with the front surface of the switching piston 18. Has been converted. The switching piston 18 is formed of a substantially columnar member having an outer diameter equal to the base end portion 33 of the shaft hole 29, and is slidable in the axial direction of the valve body 28. That is, a portion between the front surface of the switching piston 18 and the ball 34 in the shaft hole 29 is defined as a check valve switching hydraulic chamber 37. The check valve switching hydraulic chamber 37 communicates with a radial communication hole 38 formed in the valve body 28. Further, a reduced diameter portion 39 is provided in the middle of the switching piston 18. A straight hole 40 penetrating in the piston radial direction (vertical direction in FIG. 3) is formed in the reduced diameter portion 39, and is connected to a pair of oblique holes 41 extending from the switching pin base portion 17b to the axial center side of the switching piston 18. are doing. And valve body 2
8, a rear communication hole 42 is formed at a position appropriately rearwardly separated from the communication hole 38 of the check valve switching hydraulic chamber 37.
When the switching piston 18 advances to the high-pressure chamber 21 side and its corner comes into contact with the step 43 (the boundary between the reduced diameter portion 32 and the base end portion 33) of the accommodation hole 29, as shown in FIG. , And are communicated with the straight holes 40. A spring 45 is provided in the recess 44 formed at the rear end of the switching piston 18.
Is provided, and the switching pin 17 is urged in a direction in which the switching pin 17 contacts the ball 34. That is, when the switching piston 18 advances by the urging force of the spring 45 and becomes locked by the step 43, the switching pin 17 pushes the ball 34 into the ball retainer 35. Spring 4
The other end of 5 is locked by a spring stopper 46 provided on the other end side of the accommodation hole 27. A fixing bolt 47 is provided on the back side of the spring stopper 46. The fixing bolt 47 is screwed into the rear end of the accommodation hole 27, whereby the spring stopper 46 is positioned, and the valve body 28 is fixed and the switching is performed. A retraction limit for the piston 18 is defined. At the retract limit position, the switching pin 17 is separated from the ball 34, as shown in FIG. A relief hole 48 is formed in the spring stopper 46 and the fixing bolt 47 to allow the back side of the switching piston 18 to communicate with the outside air.

Then, in the horizontal cylindrical portion 7b of the housing,
A pilot hole 49 extending radially outward (downward) to connect to a communication hole 38 from the check valve switching hydraulic chamber 37;
An upper hole 50 extending radially outward and opening to the upper surface is formed to be connected to the second hole 2. Housing holes 2 for upper and lower holes 49, 50
Annular grooves 51 and 52 are formed at the opening position on the seventh side to ensure connection with the communication holes 38 and 42. The pilot hole 49 is connected to a horizontal hole 53 extending parallel to the accommodation hole 27, and the horizontal hole 53 communicates with a vertical hole 54 formed below the horizontal columnar portion 7b. The screw hole tip 55a of the connecting member 55 constituting the oil intake portion 19 is screwed into the vertical hole 54, and the oil passage 56 formed inside the screw hole tip 55a is provided at the side portion of the connecting member 55. The oil pipe 3 is connected to the connection port 57.

Accordingly, the oil is introduced from the oil intake portion 19 through the horizontal hole 53, the vertical hole 54 and the pilot hole 49 into the check valve switching hydraulic chamber 37.
When the high control oil pressure at N is supplied, the switching piston 18
Retreat until the spring contacts the spring stopper 46, the switching pin 17 moves away from the ball 34 to activate the check valve 10 (see FIG. 2), and when the low control hydraulic pressure at the time of OFF flows, the switching piston 18 moves. By pushing forward the ball 34 into the ball retainer 35 by the urging force of the spring 45, the ball 34 is separated from the small diameter portion 31 of the shaft hole, and the check valve 10 is held in an inoperative state (see FIG. 3). .

Next, the operation switching valve 2 is, as shown in FIG.
A flow control spool valve 61 as a first valve means for selectively determining the amount of engine oil from an engine oil gallery (oil pump) that is a control oil pressure supply source and supplying the control oil pressure to the brake unit 1, and a flow rate. The control spool valve 61 is mainly constituted by a switching spool valve 62 which is a second valve means for appropriately driving the control spool valve 61 by utilizing the oil pressure of the engine oil.

The flow control spool valve 61 is constructed by forming control oil passages 64 and 65 inside a cylindrical valve body 63, and is slidable in a cylinder hole 67 formed in a valve body 66 having a substantially rectangular parallelepiped shape. It is housed in. The overall axial length of the valve element 63 is slightly shorter than the axial length of the cylinder hole 67. At the lower end of the valve body 63, a concave portion 68 is formed which is concentrically depressed at the axial center position, and the bottom surface 67 of the cylinder hole 67 is formed.
A spring 69 is provided so as to be stretched between a and a and to bias upward. The valve body 66 has a cylinder hole 6
7, the oil passage 70 on the inlet side extending in the radial direction, and the cylinder hole 6 at the position on the extension of the oil passage 70 on the inlet side.
7, an oil passage 71 on the outlet side is formed extending radially outward from 7. The cylinder hole 67 is opened in the upper surface 66a of the valve body 66, and the hole bottom 67a is formed in the valve body 6.
It is located near the lower end of 6. The inlet oil passage 70 is
The inlet end is expanded in diameter and opened at the side surface of the valve body 66. A bolt portion 73a of a mounting member 73 provided at an end portion of an oil pipe 72 extending from the engine oil gallery is screwed into this opening so as to guide the engine oil into the valve body 66. The outlet-side oil passage 71 is opened on the side surface of the valve body 66 on the side opposite to the inlet-side oil passage 70, and the bolt portion 74a of the mounting member 74 of the oil pipe 3 connected to the brake unit 1 is screwed.

The control oil passages 64, 65 of the valve body 63
Is an orifice 64 having substantially the same diameter as the oil passages 70 and 71 on both sides.
And a choke 65 with a diameter sufficiently smaller than the orifice 64
And are separated from each other in the axial direction by a predetermined distance and penetrate in the radial direction of the valve body 63. Orifice 6
4 and the open end of the choke 65, both side oil passages 70, 7
An annular groove 75 for surely connecting with 1 is formed. As shown in FIG. 4, when the valve body 63 moves downward and contacts the bottom surface 67a of the cylinder hole 67, the orifice 64 is positioned so as to coincide with the oil passages 70 and 71 on both sides. When the valve body 63 is moved upward, the choke 65 is connected to the oil passages 70, 71 on both sides.
To communicate with (see FIG. 7). Then, an oblique hole 76 extending obliquely downward is provided at the outlet end of the choke 65.
Is formed, and the lower end thereof opens into the recess 68. A ball valve 77 having the same structure as the check valve 10 is provided at the lower end opening of the oblique hole 76. The ball valve 77 has an oblique hole 76.
Ball 78 with a diameter sufficiently larger than the opening of
And a ball retainer 79 having a cylindrical shape with a bottom and a ball spring (not shown) for urging the ball upward. That is, the brake unit 1 passes through the choke 65.
When the control pressure of the engine oil supplied to the valve exceeds the set resilience of the ball spring, it opens to guide excess engine oil to the recess 68 (cylinder hole 67). A discharge hole 80 formed at the lower end of the valve body 66 is communicated with the cylinder hole 67, and a return pipe 81 connected to an oil pan is attached.

Therefore, when the valve body 63 is in the lowered state, the hydraulic pressure corresponding to the engine oil pressure is supplied to the brake unit 1 as the control hydraulic pressure for operation (when ON) by the orifice 64, and when the valve body is in the raised state, the choke 65 is used to control the amount of oil. Is reduced, the hydraulic pressure significantly smaller than the engine oil pressure is supplied to the brake unit 1 as a non-actuating (OFF) control hydraulic pressure. Then, as shown in FIG. 8 and FIG. 9, since the oil amount and the oil pressure of the engine oil change depending on the engine speed, the OFF through the choke 65 is performed.
The time control oil pressure also changes, but by being bypassed by the ball valve 77, that amount is reduced (hatched portion in the figure), and a constant OFF time control oil pressure (for example, 0.1 Kgf / cm ² ) is secured. That is, the inclined hole 76 and the ball valve 77 constitute a pressure holding mechanism for keeping the low control oil pressure constant.

Next, the switching spool valve 62 is formed by forming a reduced diameter portion 80a of a predetermined length in the middle of a cylindrical valve rod 80, and the valve rod 80 is a disc-shaped valve cap 81.
It is accommodated in a vertical sliding hole 82 formed in the vertical direction so as to be vertically movable. A drive solenoid 83 for moving the valve rod 80 up and down is connected to the upper end of the valve rod 80. The drive solenoid 83 is connected to the microcomputer 5 and turned on.
It is adapted to be excited or de-energized by an operation signal of / OFF. The valve cap 81 has a lower surface 81.
a is superposed on the upper surface 61 a of the valve body 66 and fastened by a plurality of bolts 84. Valve cap 8
The upper portion of 1 is a step portion 8 that protrudes in two concentric circles at a position slightly displaced from the position of the cylinder hole 67 toward the inlet side.
5, 86 are formed, and an upper step portion 86 thereof is formed as a mounting seat for the drive solenoid 83. Sliding hole 82
Has an opening at the axial center position of the upper step portion 86, and its bottom portion 82a is defined as a diameter-expanding chamber having a slightly increased diameter.

Inside the valve cap 81, a valve driving oil passage 87 for applying the pressure of the engine oil to the valve body 80 is formed. The valve-driving oil passage 87 extends in the lateral direction intersecting the sliding hole 82, and extends vertically from both ends of the lateral direction portion to connect to the cylinder hole 67 of the valve body 66 and the inlet-side oil passage 70. It is formed in a U shape with the direction part. Valve body 6
6 includes one end of the valve driving oil passage 87 and the inlet oil passage 70.
An up-down direction connecting path 88 is formed to connect the middle of the. The other end of the valve driving oil passage 87 is connected to the cylinder hole 67.
Is formed as an enlarged diameter portion 87a having a diameter slightly smaller than
It faces the opening of the cylinder hole 67. That is, the control valve hydraulic chamber 89 is defined between the inner wall surface of the expanded diameter portion 87a and the upper surface of the valve body 63.

Therefore, as shown in FIG. 4, the valve rod 80
Is lifted upward by the activation (excitation) of the drive solenoid 83, and when the reduced diameter portion 80a is set at the intersecting position with the valve drive oil passage 87, the engine oil from the inlet side oil passage 70 is used for the valve drive. It is guided to the cylinder hole 67 as it is through the oil passage 87, and the pressure of this engine oil acts on the upper surface of the valve body 63 of the flow rate control spool valve 61 to lower it against the spring 69. . Further, when the power supply to the drive solenoid 83 is stopped and the valve rod 80 is lowered, the upper portion of the valve rod 80 closes the valve driving oil passage 87 and the control valve hydraulic chamber 89 is closed, as shown in FIG. The pressure is reduced and the valve body 63 is raised by the urging force of the spring 69.

The valve cap 81 is provided with a fine hole 90 and a return oil passage 91 for opening the oil in the control valve hydraulic chamber 89 to the atmosphere when the valve cap 81 is off.
The pore 90 has a diameter smaller than that of the valve driving oil passage 87,
The middle of the valve-driving oil passage 87 in the vertical direction portion located on the cylinder hole 67 side is connected to a position slightly above the bottom portion 82 a of the sliding hole 82. The return oil passage 91 is
As shown in FIGS. 5 and 6, it extends radially outward from the sliding hole bottom portion 82a and opens at the outer peripheral surface of the valve cap 81. Further, an O-ring 92 that is in contact with the valve body upper surface 66a is provided on the valve cap lower surface 81a at a position surrounding the valve driving oil passage 87.

When the engine braking device constructed as described above is used to increase the engine braking force, the operation processing of the microcomputer 5 is started by turning on the operation switch 4, and the optimum timing and period are obtained. Is supplied to the drive solenoid 83 of the operation switching valve 2.
When the drive solenoid 83 is activated, the switching spool valve 62
The valve rod 80 rises and causes the pressure of the engine oil to act on the valve element 63 of the flow control spool valve 61 and push it down. As a result, a flow passage having a substantially constant diameter is formed inside the valve body 66 by the oil passages 70, 71 on both sides and the orifice 64, and the ON control hydraulic pressure corresponding to the gallery pressure is applied to the brake unit 1 by the oil pipe 3.
To the oil intake section 19 of.

With this control oil pressure, the brake unit 1
Of the check valve 10 of the check valve 10 is retracted until it hits the spring stopper 46.
Separate from 4. The check valve 10 is now in the operating state, and the supplied engine oil flows only toward the high hydraulic chamber 21. When this hydraulic pressure acts on the piston head 8a,
The release piston 8 is pushed down and abuts on the exhaust valve 6 immediately before the valve is closed via the intermediate shaft 26, and holds it in a slightly depressed state regardless of the rocking position of the rocker arm. That is, the exhaust valve 6 is slightly opened without being seated, and the cylinder is always opened also in the compression stroke and the expansion stroke including the overlap timing at the top dead center.

As a result, the compression pressure is released in the expansion stroke, and the piston is decelerated by increasing the negative work. That is, an effective brake pressure that provides greater braking performance than the exhaust brake is obtained. A large force in the valve closing direction is applied to the release piston 8 by the compression pressure in the cylinder of the engine. When the release piston 8 is depressed, the check valve 10 causes the oil to flow out of the high hydraulic pressure chamber 21. As a result, the high-pressure chamber 21 quickly generates a high-pressure reaction force in the high-pressure chamber 21. When the high-pressure reaction is maintained, the exhaust valve 6 is prevented from closing and reaches the predetermined lift position. Will be retained. Further, as shown in FIG. 2, when the switching piston 18 is retracted, the rear communication hole 42 is not communicated with the straight hole 40 of the reduced diameter portion 39 and is in a closed state. The engine oil that has entered the chamber 37 is not discharged and is not wasted.

When it is not necessary to increase the engine brake and the operation switch 4 is turned "OFF" or the accelerator pedal is depressed, the power supply to the drive solenoid 83 is stopped and the valve rod 80 of the switching spool valve 62 is closed. Then, the valve driving oil passage 87 is closed and closed. As a result, the pressure in the control valve hydraulic chamber 89 decreases, and the valve body 63 of the flow control spool valve 61 rises due to the urging force of the spring 69. At this time, the engine oil in the control valve hydraulic chamber 89 and the valve driving oil passage 87 is discharged through the return oil passage 91 through the fine hole 90 and the sliding hole bottom portion 82a, and the lift of the valve body 63 is smoothed. As the valve body rises, the inlet-side oil passage 70 and the outlet-side oil passage 71 are communicated with each other by the choke 64, the flow rate of the engine oil is throttled, and the brake unit 1 is supplied with a low control hydraulic pressure when OFF. It
This control oil pressure causes the switching piston 18 to move to the spring 4
The ball 34 is advanced by the urging force of No. 5, and the ball 34 is pushed into the ball retainer 35, so that the check valve switching hydraulic chamber 37 and the high hydraulic chamber 21 are kept in communication. With this, the high hydraulic chamber 21
The engine oil of check valve switching hydraulic chamber 37, oblique hole 4
1, the high pressure chamber 21 is discharged from the upper hole 52 via the straight hole 40 and the rear communication hole 42, the high hydraulic chamber 21 is depressurized, and the release piston 8 is lifted to the upper limit position by the return spring 25 and separated from the intermediate shaft 26. Then, the exhaust valve 6 is returned to a position where it does not interfere with the opening / closing operation in the normal combustion cycle.

As described above, as the operation switching valve 2, the flow rate control spool valve 6 that allows the engine oil amount to pass through the orifice 64 and the choke 65 as it is, or to pass the engine oil through the choke 65.
1 and an electromagnetically driven switching spool valve 62 that drives the flow rate control spool valve 61 by using the engine oil pressure to supply a control hydraulic pressure that brings the brake unit 1 into an operating state or a non-operating state. Therefore, engine oil is constantly supplied to the hydraulic circuit 9 of the brake unit 1, and there is no risk of air being mixed in, and it is possible to perform operation switching with good responsiveness. That is, it is not necessary to form an oil passage for bleeding air in the hydraulic circuit 9 or the release piston 8, and the number of processing steps can be reduced. Since the control oil pressure can be changed only by the operation of the flow rate control spool valve 61, it is not necessary to provide a switching valve for ON and a switching valve for OFF, and a very simple structure can be obtained. Further, since the engine oil supplied to the brake unit 1 is used for the drive control of the flow rate control spool valve 61, a separate control drive source such as a compressor is not required, which is extremely versatile.

The choke 6 of the flow control spool valve 61
Since the slanted hole 76 and the ball valve 77 are provided in the No. 5, the control pressure at the time of OFF can be maintained at a constant pressure even if the supply pressure of the engine oil rises, and there is no fear of malfunction, etc., and it overflowed. Engine oil can be collected. Further, the operation switching valve 2 of this embodiment
Since both spool valves 61 and 62 are integrally formed on the valve body 66 and the valve cap 81, further compactness, weight reduction, and cost reduction can be achieved.

In the brake unit 1 of this embodiment, the release piston 8 is provided in the housing 7 arranged above the exhaust valve 6 to lift the exhaust valve 6, and the check valve 10 and the switching pin are provided. 17 and switching piston 1
8 is provided to maintain high hydraulic pressure in the hydraulic circuit 9 and to supply and discharge the oil. Therefore, the compression pressure in the cylinder can be released with a simple and compact structure, and the engine braking force can be increased. Is obtained. Since the check valve 10, the switching pin 17, and the switching piston 18 are integrally formed on the lateral valve body 28, further compactness and cost reduction can be achieved. Since the release piston 8 is located coaxially with the exhaust valve 6 and pushes the intermediate shaft 26, the valve operating system such as the rocker arm is completely loaded with the compression pressure releasing operation. Since it does not require any major changes in its structure, it is extremely versatile. Switching piston 1
8 is provided with a reduced diameter portion 39 and holes 40 and 41 at predetermined positions,
When switching from brake operation to non-operation, it communicates with the rear communication hole 42 and the upper hole 50 to release the high pressure engine oil to the atmosphere, and does not communicate with it when the brake is operated, ensuring responsiveness of operation / non-operation. While
Oil consumption can be minimized.

The configuration of the brake unit is shown in FIG.
The present invention is not limited to that shown in FIG. 3 and can be widely applied to an engine braking device provided with a brake unit that operates by control hydraulic pressure to release the compression pressure.

[0030]

In summary, according to the present invention, the operation switching of the engine braking device can be performed with excellent responsiveness, and with a compact, lightweight and low-cost configuration, and a separate drive source such as a compressor is required. It has an excellent effect of being extremely versatile.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an engine braking device showing an embodiment of the present invention.

FIG. 2 is a side sectional view showing the brake unit of FIG.

3 is a side sectional view showing a main part of FIG. 2. FIG.

FIG. 4 is a side sectional view showing the operation switching valve of FIG. 1.

FIG. 5 is a plan view of FIG.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a side sectional view for explaining the operation of FIG.

FIG. 8 is a relationship diagram between the engine speed and the amount of engine oil for explaining the operation of the present invention.

FIG. 9 is a relationship diagram between the engine speed and the oil pressure of engine oil for explaining the operation of the present invention.

[Explanation of symbols]

 1 Brake Unit 2 Operation Switching Valve 5 Microcomputer (Controller) 61 Flow Control Spool Valve (First Valve Means) 62 Switching Spool Valve (Second Valve Means) 76 Oblique Hole (Pressure Holding Mechanism) 77 Ball Valve (Pressure Holding Mechanism) )

Claims (3)

[Claims] 1. An engine brake device comprising: a brake unit that operates by control hydraulic pressure to release a compression pressure during engine braking; and an operation switching valve that switches the control hydraulic pressure to activate or deactivate the brake unit. The operation switching valve selectively determines the amount of oil from the control oil pressure supply source and supplies the brake unit with the control oil pressure for operation or non-operation, and the first valve means; An engine braking device comprising: a second valve means for appropriately driving the valve means by the hydraulic pressure of the control hydraulic pressure supply source. 2. The engine braking device according to claim 1, wherein the first valve means has a pressure holding mechanism for keeping the control hydraulic pressure constant. 3. The engine braking device according to claim 1, wherein the second valve means is driven by a controller for controlling the operation of the brake unit according to the engine operating condition and the like.