JPH09250319A - Engine brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the volume of an entire device, and to prevent the increase in the total height of an engine, the increase in its weight, and the increase in cost. SOLUTION: An engine brake device is provided with a releasing piston 3 by which an exhaust valve 1 is lifted to release the compressive pressure inside a cylinder 2, a hydraulic piston 4 by which a hydraulic pressure for operating the releasing piston 3 is produced, a releasing exclusive cam 5 for operating the hydraulic piston 4 at a prescribed time, and a housing frame 9 which has a hydraulic circuit 6 for introducing oil pressure and housing parts 7, 8 for housing the pistons 3, 4 and by which the respective releasing-piston housing parts 7 and the respective hydraulic piston housing parts 8 being adjacent are connected with each other. By this constitution, the housing frame 9 can be formed in a simple shape, and the volume of the entire device can be reduced.

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 that increases engine braking force by releasing compression pressure in a cylinder.

[0002]

2. Description of the Related Art Recently, various engine braking devices have been proposed which increase the engine braking force by releasing the compression pressure in the cylinder by lifting the exhaust valve other than the exhaust stroke when the engine brake is used. ing. As a mechanism for lifting the exhaust valve, there is known a mechanism in which a housing having a hydraulic circuit is provided in the upper part of the valve mechanism and the piston for lifting the exhaust valve is pushed by the high hydraulic pressure.

[0003]

By the way, in the conventional hydraulic engine braking device, the hydraulic drive source is obtained from the valve operating valve of another cylinder in order to drive the piston at a timing near the top dead center. The units for constructing the line are all cylinders integrated or have a two-divided structure, and there are problems that the volume of the entire apparatus is large, the engine height is increased, the weight is increased, and the cost is increased.
That is, depending on the type of engine, it was not possible to meet the regulation.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a releasing piston for lifting an exhaust valve to release a compression pressure in a cylinder, and a hydraulic pressure for operating the releasing piston. A hydraulic piston and a release-only cam for driving the hydraulic piston at a predetermined time,
The present invention is provided with a hydraulic circuit that guides hydraulic pressure and a housing portion that houses the piston, and a housing frame that connects the release piston housing portions of adjacent cylinders and the hydraulic piston housing portions to each other. The housing frame preferably has a check valve for supplying hydraulic oil to the hydraulic circuit and appropriately closing the hydraulic circuit, and a switching pin for canceling the operation of the check valve. With the above configuration, the release-only cam drives the hydraulic piston to generate a high hydraulic pressure, and lowers the release piston connected by the hydraulic circuit. Due to this lowering, the exhaust valve is lifted, and when the engine brake is used, the compression pressure in the cylinder is released at a predetermined timing to provide a large braking force. The check valve appropriately closes the hydraulic circuit to maintain the high hydraulic pressure generated by driving the hydraulic piston. The switching pin releases the high pressure in the hydraulic circuit by releasing the operation of the check valve when the supply of the hydraulic oil is stopped, and prevents the release piston from being driven even if the hydraulic piston is driven.

[0005]

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

1 to 3 show an engine braking device to which the present invention is applied. This engine braking device includes a release piston 3 for lifting the exhaust valve 1 to release the compression pressure in the cylinder 2, a hydraulic piston 4 for generating a hydraulic pressure for operating the release piston 3, and a hydraulic piston 4. It is mainly configured by a release-only cam 5 for driving at a predetermined time, a hydraulic circuit 6 for guiding hydraulic pressure, and a housing frame 9 having accommodating portions 7, 8 for accommodating the pistons 3, 4.

The exhaust valve 1 is composed of a valve body 12 seated on an open end (valve seat) 11 of an exhaust port 10 and a valve shaft 13 attached to an axial center position of the valve body 12 and extending upward. There is. In this embodiment, each cylinder 2 is provided with a pair of exhaust ports 10 and intake ports 14, and an exhaust valve 1 is arranged in each exhaust port 10. The valve shaft 13 is provided with a return spring 15 that urges the valve shaft 13 in the valve closing direction (upward). The head portion of the valve shaft 13 has a valve bridge 1 that engages with one end of a rocker arm 16.
7 are provided. The rocker arm 16 has a central portion pivotally supported by a rocker shaft 18, and the other end engaged with a valve operating cam 20 via a cam follower 19. That is, the pair of exhaust valves 1 is lifted by the cam-driven rocker arm 16 at a predetermined timing during the exhaust stroke. A release pin 21 is provided upright on the extension of the valve shaft of one exhaust valve 1. The release pin 21 extends vertically through the end portion of the valve bridge 17, and is slidably supported by a sleeve 22 provided at the end portion. A flange 23 that engages with the lower surface of the sleeve 22 is formed at the lower end of the release pin 21. When the release pin 21 is pushed downward, the exhaust valve 1 is lifted regardless of the operation of the rocker arm 16, and the rocker arm 16 is also lifted. When is swung, the exhaust valve 1 is pushed by being integrated with the valve bridge 17. The outer circumference of the sleeve 22 is threaded, and is screwed into a vertical through hole 24 formed in the valve bridge 17. Also, on the upper part of the sleeve 22, the valve bridge 1
A nut 25 for adjusting the positional relationship with 7 (the upper limit of the release pin 21) is screwed. That is, the sleeve 22
Is formed as an adjustable screw.

The housing frame 9 includes a release piston 3
Standing substantially cylindrical release piston housing 7 for housing
And an upright substantially cylindrical hydraulic piston accommodating portion 8 for accommodating the hydraulic piston 4, and a circuit portion 26 which is bridged between these accommodating portions 7, 8 and in which the hydraulic circuit 6 is formed. There is. The hydraulic circuit 6 in the circuit portion 26 is formed as a linear oil passage 27 extending along the center thereof.
The circuit portion 26 is provided horizontally above the rocker arm 16 and extends in a direction intersecting the longitudinal direction of the engine (crankshaft A) at an angle close to a right angle in a plan view. The release piston accommodating portions 7 and the hydraulic piston accommodating portions 8 of the adjacent cylinders 2 are connected to each other by a linear connecting portion 28. The connecting portion 28 extends along the longitudinal direction of the engine. That is, the housing frame 9 includes the four piston housing portions 7 and 8 in a plan view by the circuit portion 26 and the connecting portion 28.
It is integrally formed in a rectangular shape (parallelogram) with the apex as the apex. Support parts 29 and 30 extending in the engine width direction and obliquely downward are integrally formed in the piston housing parts 7 and 8, respectively. Support part 2 of release piston accommodating part 7
The tip of 9 is attached to the upper surface of the cylinder head 31 via bolts and nuts 32, and the tip of the support portion 30 of the hydraulic piston accommodating portion 8 is attached to the upper surface of the cam bracket 34 that supports the camshaft 33 by bolts and nuts 35. It is installed. Therefore, one housing frame 9 has its four corners fixed by bolts and nuts 32 and 35. In the case of an in-line six-cylinder engine, three housing frames 9 are fixed independently.

Next, as shown in FIG. 6, the release piston 3 is composed of a piston head portion 36 having a short cylindrical shape and a rod portion 37 extending coaxially downward from the piston head portion 36. The piston head portion 36 is formed so as to slide in a vertical cylinder chamber 38 provided in the release piston housing portion 7. An upper part of the cylinder chamber 38 communicates with the linear oil passage 27, and a lower part thereof is formed as a housing hole 39 opened on the lower surface of the release piston housing part 7. Accommodation hole 3
A spring support plate 40 having an axial hole through which the rod portion 37 is inserted is attached to the opening position of 9 via a snap ring 41. A double return spring 42 is provided between the spring support plate 40 and the lower surface of the piston head 36, and urges the release piston 3 upward. The rod portion 37 extends below the spring support plate 40, and its lower end is formed so as to contact the upper end of the release pin 21. Further, an air vent hole 43 is formed inside the release piston 3, extends downward from the upper surface of the piston head portion 36 along its axial direction, and is opened on both sides of the rod portion 37.

At the upper part of the cylinder chamber 38, an upper limit bolt 44 whose lower end abuts the upper surface of the piston head 36.
Is provided. The upper limit bolt 44 is screwed into a vertical hole formed in the upper wall of the release piston housing portion 7, and the projecting length of the upper limit bolt 44 can be adjusted by a nut 45. That is, as a result of this adjustment, as shown in FIG. 6, when the piston head 36 comes into contact with the upper limit bolt 44 due to the upward movement of the release piston 3, the lower end of the rod portion 37 moves from the upper end of the release pin 21 when the valve is seated. They will be separated by a predetermined small gap (gap) S. The upper limit bolt 44 is formed in a bottomed cylindrical shape with an opening at the bottom, and a pin 46 slidable in the vertical direction is provided therein. A retaining ring 47 is fitted on the pin 46, and the upper limit bolt 4
The vertical stroke is defined by engaging with a notch 48 formed on the peripheral surface of No. 4. A spring 49 is provided between the upper end of the pin 46 and the upper inner wall of the upper limit bolt 44,
The pin 46 is biased downward. The tip of the pin 46 abuts on the opening position of the air vent hole 43 of the piston head 36. In this abutting state, the tip of the pin 46 moves up and down to follow the up-and-down movement of the release piston 3 to cause the hydraulic circuit 6 to move. In the process of increasing the pressure of the air, the air contained in the engine oil (operating oil) is released, and when a predetermined high pressure is reached, the air vent hole 43
Is to be closed.

The hydraulic piston 4 is, as shown in FIG.
The release piston 3 is formed of a cylindrical body having a diameter smaller than that of the piston head 36, and is inserted into a vertical cylinder hole 50 provided in the hydraulic piston accommodating portion 8. A cam follower 52 is provided at the lower end of the hydraulic piston 4 via a bracket 51. The cam follower 52 is formed as a roller that engages with the release-only cam 5. The upper part of the cylinder hole 50 communicates with the other end of the linear oil passage 27, and the lower part is opened at the lower end of the hydraulic piston housing portion 8. Therefore, when an upward force is applied to the hydraulic piston 4 by the release cam 5 while the hydraulic circuit 6 is filled with the engine oil, the hydraulic piston 4 will move into the cylinder hole 50.
The pressure rises in the section of the release piston 3 up to the piston head 36. That is, in the hydraulic circuit 6, the cylinder hole 50 above the hydraulic piston 4, the linear oil passage 27, and the cylinder chamber 38 above the release piston 3 act as the high hydraulic chamber 87. A flange 53 is formed between the hydraulic piston 4 and the bracket 51, and the flange 53 comes into contact with the lower surface of the hydraulic piston housing portion 8 to position the upper limit of the vertical movement of the hydraulic piston 4. The tip of the return leaf spring 54 is engaged with the lower surface of the flange 53 to urge the hydraulic piston 4 upward. That is, when the engine oil is not supplied to the hydraulic circuit 6, the hydraulic piston 4 is held by the return leaf spring 54 at a position where it does not come into contact with the release cam 5. The base end of the return leaf spring 54 is attached to a support portion 55 projecting from the side surface of the hydraulic piston housing portion 8 with a small bolt 56, and the tip 54 a is inserted between the bracket 51 and the flange 53. It is curved appropriately.

The release-dedicated cam 5 is attached to the cam shaft 33 of the valve operating mechanism and is positioned close to the valve operating cam 20 that drives the exhaust valve 1. The cam height portion 5a of the release-only cam 5 is the cam height portion 20 of the valve operating cam 20.
a and the shaft center angle are formed with a phase separated by approximately 130 to 140 degrees. That is, by driving the hydraulic piston 4 at an appropriate timing after the piston top dead center preceding the exhaust stroke, a high hydraulic pressure is generated in the hydraulic circuit 6, and the release piston 3 is operated according to the hydraulic pressure,
The exhaust valve 1 is lifted.

On the release piston 3 side of the housing frame 9, a valve portion 57 and an oil intake portion 58 for appropriately supplying and discharging engine oil to and from the hydraulic circuit 6 are provided. The valve portion 57 is formed on a horizontal columnar frame end portion 59 formed on an extension of the circuit portion 26. FIG.
As shown in FIG. 5, a lateral hole 60 communicating with the high hydraulic chamber 87 is formed in the frame end portion 59, and the valve unit 61 is fitted into the lateral hole 60. As shown in FIG. 4, the valve unit 61 has a valve body 63 having a shaft hole 62 for partitioning the supply side of the hydraulic circuit 6, and a valve body 63 formed at the tip of the valve body 63 for guiding engine oil to the hydraulic circuit 6. The check valve 64 is appropriately closed, a switching pin 65 for releasing the operation of the check valve 64, and a switching piston 66 for operating the switching pin 65. Valve body 63
The shaft hole 62 of the high hydraulic chamber 8 is, as shown in FIG.
The 7 side is formed with a small diameter and the opposite side is formed with a large diameter. A check valve 64 is provided in the small diameter portion 62a, and a switching piston 66 is provided in the large diameter portion 62b. The check valve 64 includes the shaft hole small-diameter portion 6
Ball 67 having a diameter sufficiently larger than 2a, and ball 67
Retainer 68 for holding the ball at the position of the hole end, and a ball spring 69 provided inside the ball retainer 68.
And That is, the ball 67 is movable in the axial direction on the extension of the shaft hole 62, and the engine oil is formed to pass through only in the direction from the shaft hole 62 to the high hydraulic chamber 87. The ball retainer 68 is a ball 6
It is a bottomed cylindrical member having an outer circumference having an inner diameter substantially equal to the diameter of 7, and the base end of the outer circumference is attached to the end of the valve body 63. And the ball retainer 68 has
As shown in FIG. 4B, when the ball 67 is pushed against the ball spring 69, the high hydraulic chamber 87
A slit 70 for communicating with the shaft hole 62 is formed.

The switching pin 65 has an outer diameter smaller than the small diameter portion 62a of the shaft hole and a total length sufficiently longer than its axial length, and its base end is integrally connected to the axial center position of the switching piston 66. ing. The switching piston 66 is a bottomed cylindrical member having an outer diameter equal to the large diameter portion 62b of the shaft hole, and is slidable in the axial direction of the valve body 63. That is, in the shaft hole 62, the front surface of the switching piston 66 and the ball 67 are partitioned as a switching hydraulic chamber 71. As shown in FIG. 4C, a flange 72 is formed at the base end of the switching piston 66, and the flange 72 is locked to the stepped portion 73 formed in the large diameter portion 62b of the shaft hole. It is like this. The stepped portion 73 is located inward from the opening end of the shaft hole 62 by a predetermined distance. And the switching piston 66
A spring 74 is provided inside and is urged in a direction of contacting the ball 67. When the switching piston 66 moves forward and is locked by the stepped portion 73 by this urging force, the switching pin 65 causes the ball 67 to move to the ball retainer 68.
It is designed to be pushed in. The other end of the spring 74 is locked by a spring stopper 75 provided on the other end of the lateral hole 60, as shown in FIG. A fixing bolt 76 is provided on the back side of the spring stopper 75,
By screwing the fixing bolt 76 into the lateral hole 60, the valve unit 61 is inserted through the spring stopper 75.
Is fixed. That is, this spring stopper 75 defines the retreat limit of the switching piston 66, and in this retracted position, the switching pin 65 causes the ball 6 to move.
It is designed to move away from 7. An air hole 77 communicating with the shaft hole 62 is formed in the spring stopper 75 and the fixing bolt 76 to release the back pressure of the switching piston 66.

As shown in FIG. 4, the valve body 63 is formed with an upper hole 78 and a lower hole 79 extending radially from the switching hydraulic chamber 71. The upper hole 78 communicates with an open hole 80 formed in the frame end 59, and discharges high-pressure oil flowing from the high hydraulic chamber 87 to the outside of the housing frame 9 (open to the atmosphere). ing. On the other hand, the prepared hole 79 communicates with the oblique hole 81 formed below the frame end 59. A tip 82a of a connecting member 82, which serves as an oil intake portion 58, is screwed into the swash hole 81, and an oil passage 83 coaxial with the swash hole 81 extends from the tip 82a to the outside of the housing to form a side portion of the connecting member 82. It is open at. This opening is formed as a connection port 85 with a supply pipe 84 that supplies low-pressure engine oil. Therefore, when the hydraulic pressure is supplied from the oil intake portion 58 to the switching hydraulic chamber 71, the switching piston 66 retracts to activate the check valve 64, and when the hydraulic pressure supply is stopped, as shown in FIG. , The switching piston 66 advances and the check valve 64
Is set to the inactive state.

As shown in FIG. 1, the supply pipe 84 is
It extends in the longitudinal direction of the engine so as to connect the oil intake parts 58, and is connected to an oil gallery of an oil supply source or an oil dedicated pump via an electromagnetic valve (not shown).
The solenoid valve is turned on / off by operating the switch installed in the driver's seat.
By doing so, the oil sent from the engine oil gallery or the dedicated pump is supplied to each oil intake portion 58 or stopped. Note that this operation switch is set to "O" only when the engine brake is used, in other words, when the accelerator pedal is not depressed.
It may be configured to be “N”.

In addition, as shown in FIG. 2, a cylinder head cover 86 is attached to the upper part of the cylinder head 31 and has a substantially rectangular cross section to cover the rocker arm 16 and the housing frame 9.

When the desired braking force is obtained by the engine braking device constructed as described above, the operation switch is turned on to supply the engine oil to the oil intake portion 58. When this engine oil enters the switching oil pressure chamber 71, the switching piston 66 retracts until it abuts the piston stopper 75, separating the switching pin 65 from the ball 67 of the check valve 64. Check valve 64
Becomes an operating state, and the supplied engine oil flows into the high hydraulic pressure chamber 87. Since the engine oil at this time contains air, it is discharged through the air vent hole 43. When air is removed and the hydraulic pressure in the high hydraulic pressure chamber 87 rises to reach a predetermined value, the check valve 64 causes the high hydraulic pressure chamber 87 to move.
Is closed, and a high hydraulic pressure is formed by driving the hydraulic piston 4 by the cam 5 for exclusive use of the release, and the hydraulic pressure acts on the piston head 36 of the release piston 3, and the release piston 3
Is depressed. When the release piston 3 descends, the exhaust valve 1 lifts via the release pin 21.
That is, the exhaust valve 1 is slightly opened by the amount that the clearance S is subtracted from the downward stroke of the release piston 3, and releases the compression pressure from the inside of the cylinder 2 near the top dead center of the piston. The expansion pressure is now much lower than the compression pressure, and the piston of the engine, which is moving by inertia, is braked by increasing the negative work. After being released, the release piston 3 is raised by the return spring 42 and pushes the hydraulic piston 4 back to the cam base of the release-only cam 5.
That is, the pistons 3 and 4 perform a seesaw motion via the hydraulic circuit 6. During this seesaw movement, the high hydraulic chamber 8
The engine oil leaking from 7 is appropriately replenished from the check valve 64 to maintain the high pressure.

When there is no need to increase the engine brake and the operation switch is turned "OFF", the supply of engine oil is stopped and the switching piston 66 moves forward by the urging force of the spring 74 to move the ball 67 to the ball retainer 68.
It is pushed in and the switching hydraulic chamber 71 and the high hydraulic chamber 87 are maintained in communication with each other. As a result, the engine oil in the high hydraulic chamber 87 is discharged from the open hole 80 via the switching hydraulic chamber 71, the high hydraulic chamber 87 is in a depressurized state, and the hydraulic piston 4
Even if the pressure rises, the release piston 3 is not acted upon by high hydraulic pressure. Therefore, the release piston 3 is raised to the upper limit position by the return spring 42, separated from the release pin 21, and returned to the position where the opening / closing valve operation of the exhaust valve 1 in the normal combustion cycle is not hindered. Also hydraulic piston 4
Is held by the return leaf spring 54 at a position where it does not contact the release cam 5.

As described above, the hydraulic piston 4 is driven near the piston top dead center by the release cam 5, and the release piston 3 is lowered by the generated high hydraulic pressure to cause the exhaust valve 1 to move.
Is lifted, the compression pressure in the cylinder 2 can be reliably released, and a desired engine braking force can be obtained. And housing frame 9
Since the connecting portion 28 that connects the release piston housing portions 7 of the adjacent cylinders 2 and the hydraulic piston housing portions 8 of the adjacent cylinders 2 to each other is formed, the structural strength and the mountability are excellent, and a simple shape can be obtained. The total volume can be reduced. That is, in the synchronous engine braking device that releases the compression pressure at the timing near the piston top dead center,
It is possible to prevent an increase in the overall height of the engine, an increase in weight, and an increase in cost. And the release piston 3 is the exhaust valve 1
Since it is located on the same axis as the rocker arm 1
Since the valve operating system such as 6 does not receive any load due to the compression pressure releasing operation and does not require a large change, the versatility is improved.

Further, the check valve 64 and the switching pin 65 are provided to maintain a high hydraulic pressure in the hydraulic circuit 6 and to supply and discharge the oil, and these are integrally formed by the horizontal valve unit 61. Further, it is possible to achieve further miniaturization, cost reduction, and good responsiveness.

The present invention is not limited to the six-cylinder engine,
It can be widely applied to four-cylinder engines and the like.

[0023]

In summary, according to the present invention, the volume of the entire apparatus can be reduced, the overall height of the engine can be increased, and the weight can be increased.
It has an excellent effect of preventing high cost.

[Brief description of drawings]

FIG. 1 is a plan view of an engine braking device showing an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a sectional view of a main part of FIG.

4A and 4B are views showing a main part of FIG. 3, in which FIG. 4A is a sectional view, FIG. 4B is a front view of a part thereof, and FIG. 4C is a front view of another part.

5 is a partial cross-sectional view for explaining the operation of the main parts of FIG.

FIG. 6 is a cross-sectional view for explaining the operation of another main part of FIG.

[Explanation of symbols]

 1 Exhaust Valve 2 Cylinder 3 Release Piston 4 Hydraulic Piston 5 Dedicated Cam 6 Hydraulic Circuit 7 Release Piston Housing 8 Hydraulic Piston Housing 9 Housing Frame 28 Connection 29, 30 Support 31 Cylinder Head 64 Check Valve 65 Switching Pin

Claims (2)

[Claims] 1. A release piston for lifting an exhaust valve to release a compression pressure in a cylinder, and a hydraulic piston for generating a hydraulic pressure for operating the release piston,
A release-dedicated cam for driving the hydraulic piston at a predetermined time, a hydraulic circuit for guiding the hydraulic pressure, and an accommodating part for accommodating the piston, and adjacent release piston accommodating parts and hydraulic piston accommodating parts of adjacent cylinders. An engine braking device, comprising: a housing frame that connects the two. 2. The housing frame has a check valve for supplying hydraulic oil to the hydraulic circuit and appropriately closing the hydraulic circuit, and a switching pin for canceling the operation of the check valve. 1. The engine braking device according to 1.