WO2012126166A1

WO2012126166A1 - Engine brake device positioned by valve stem

Info

Publication number: WO2012126166A1
Application number: PCT/CN2011/002184
Authority: WO
Inventors: 杨洲
Original assignee: 奚勇
Priority date: 2011-03-24
Filing date: 2011-12-26
Publication date: 2012-09-27
Also published as: CN102691542A; CN102691542B

Abstract

Disclosed in the present invention is an engine brake device positioned by a valve stem. The device is used in an engine having a single rocker arm for opening a single valve and comprises a brake driving mechanism (100) and a brake control mechanism. The brake driving mechanism (100) comprises a brake piston cylinder sleeve (400), a brake piston (160) and a valve lift resetting mechanism (150). The brake piston cylinder sleeve (400) is located below a rocker arm (210). The brake piston (160) is arranged in a brake piston hole (190) provided on the lower side face of the brake piston cylinder sleeve (400). A brake device positioning hole (191) is arranged on the lower end surface of the brake piston (160), and sleeved on the stem of the valve. The valve lift resetting mechanism (150) can be opened and closed according to the distance between the rocker arm (210) and the brake piston cylinder sleeve (400), so that the valve lift is reset. The brake control mechanism enables the brake driving mechanism (100) to move between a non-operation position and an operation position. The whole brake mechanism is integrated into an existing engine valve drive chain, so the device has a compact structure and can be installed and adjusted conveniently. Consequently, the weight and height of the engine are reduced, the engine brake device is simplified, and the reliability and durability of the engine are improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the field of machinery, and more particularly to the field of valve actuation for vehicle engines, and more particularly to an engine brake device that is positioned by a valve stem.

Background technique

Engine braking can be divided into compression release type braking and deflation type braking. The engine's compression-release brake opens the exhaust valve at the end of the engine piston compression stroke and closes the exhaust valve in the early stages of the expansion stroke (generally before the exhaust valve opens normally). A precedent for a compression-release type of brake device is disclosed by Cummins in U.S. Patent No. 3,220,392, 1965. The brake system passes the mechanical input through the hydraulic circuit to the exhaust valve to be opened. The hydraulic circuit typically includes a primary piston that reciprocates within the primary piston bore from a mechanical input of the engine, such as the motion of the engine fuel injection cam or the movement of an adjacent exhaust cam. The movement of the primary piston is transmitted by hydraulic fluid to the secondary piston on the hydraulic circuit to reciprocate within the secondary piston bore, and the secondary piston acts directly or indirectly on the exhaust valve to produce valve actuation of the engine brake operation.

The deflated brake of the engine is that the exhaust valve maintains a small amount of constant opening (partial periodic bleed brake) in part of the cycle, in addition to the normal opening, or during the period of the non-exhaust stroke (intake stroke, compression) Stroke, and expansion stroke) maintain a small amount of constant opening (full cycle bleed brake). The main difference between the partial cycle bleeder brake and the full cycle bleeder brake is that the former does not slam the exhaust valve during most of the intake stroke. The inventors have provided related descriptions and examples for the deflated engine braking system and method in U.S. Patent No. 6,594,996.

There are two main differences between the compression release type brake and the deflated type brake of the engine. The main difference between the first point is that the opening phase (braking time) of the brake exhaust valve is different. The brake exhaust valve of the full cycle bleeder brake is always open and therefore does not involve the opening time. The opening time of the brake exhaust valve of the partial cycle bleed type brake is late in the intake stroke of the engine; and the opening time of the brake exhaust valve of the compression release type brake is at the later stage of the compression stroke of the engine, Partial cycle The brake-exhaust valve of the air brake is opened much later, so the load to be opened is much larger. The second difference is that the opening height of the brake exhaust valve (brake valve rise) is different. The brake valve of the brake valve of the deflated brake is approximately 0.5 to 1.0 mm (typically less than 1. 0 let), and the brake valve of the brake exhaust valve of the compression release type brake The lift is approximately 2. 0 to 3. 5mm (the brake valve of the hydraulic brake is generally greater than 2. 0mm. The above difference results in different design requirements and braking performance. The compression release type brake power is greater than the deflated brake However, the brake opening load of the deflated brake is much smaller than that of the compression release type brake. The deflated brake device must be used in combination with the exhaust brake device (such as the exhaust butterfly valve), and the compression release brake device can be used alone. (The exhaust brake is not necessarily required).

A precedent for the engine full cycle bleed brake system is disclosed by Muir in 1970 in U.S. Patent No. 3,525,317. The brake system divides the engine brake into three gears. The first gear is the braking caused by the friction loss caused by the engine and the moving parts of the vehicle. The second gear is the full cycle bleed brake generated by keeping the exhaust valve of the engine continuously for a small amount of constant opening. The third gear is to add an exhaust butterfly valve based on the full-cycle deflation brake of the second gear to generate a combined brake.

In U.S. Patent No. 5,692,469, the disclosure of U.S. Patent No. 5,692,469, issued to U. Apparatus and method for moving a device. When the exhaust back pressure is high enough, the exhaust valve floats or bounces near the end of the intake stroke. During the float of the exhaust valve, it is intervened with a brake device, that is, before the floating exhaust valve is closed, it is intercepted by a hydraulically controlled piston, preventing it from closing, keeping it small The constant opening causes a partial cycle bleed brake (the exhaust valve closes after the exhaust stroke). The brake system is an engine for a single exhaust valve per cylinder. In 2006, Rammer et al. extended the above technology to an engine with a double exhaust valve per cylinder (US Patent No. 7013867, Chinese Patent No. 200310123153. 7). The above-described deflated brake system requires an additional brake bracket on the engine, which is mainly used to reset the lift of the brake valve in addition to the brake load.

Cummins Engine Company's Gustafson In U.S. Patent No. 6,253,730, an integrated rocker brake system with a valve lift reset mechanism is disclosed to solve the asymmetric load and brake valve caused by opening a single valve (internal valve) during braking. The lift curve is larger than the lift curve of the non-brake valve (external valve) or the conventional valve (the opening is larger, the closing is later). The valve lift reset mechanism resets or retracts the brake piston in the rocker arm before the brake valve reaches the maximum brake valve rise, so that the brake valve returns to the valve seat before the main valve action starts, and the valve bridge returns to the horizontal position. The rocker arm balances the brake valve (internal valve) and the non-brake valve (external valve) to eliminate any asymmetrical loads. However, its valve lift reset mechanism does not work reliably and is not easy to install and commission.

A device that uses a double rocker to open a single valve brake is disclosed in Jan. 7, Jan., J. J., and Mestrik, in US Patent No. 7,392,772. In addition to the conventional exhaust rocker arm, a dedicated brake rocker is added to the side. Brake pistons and brake control valves are added to the conventional exhaust rocker arm. When braking is required, the brake piston in the conventional exhaust rocker arm is moved from the retracted inoperative position to the extended operating position and is coupled to the dedicated brake rocker arm. Dedicated brake cam drives a dedicated brake rocker. The dedicated brake rocker oppresses the brake piston. The brake piston then pushes the exhaust rocker arm to open an exhaust valve brake below the exhaust rocker arm. The advantage of this brake system is the use of dedicated brake cams and dedicated brake rockers to optimize brake power. However, the disadvantage is that the entire brake system is too complicated, taking up too much installation space, the exhaust rocker arm is too bulky, its moment of inertia is too large, and it is subjected to a large lateral load during braking.

Summary of the invention

SUMMARY OF THE INVENTION It is an object of the present invention to provide an engine brake device that is positioned by a valve stem. The engine brake device positioned by the valve stem is described in the prior art as a single rocker open valve (or single valve). The engine has complex braking system, unreliable valve lift reset mechanism, is not easy to install and debug, and has a cumbersome mechanism, a large space and a brake eccentric load.

The engine brake device positioned by the valve stem of the present invention comprises a brake drive mechanism and a brake control mechanism disposed on the engine, wherein the engine includes a valve drive chain, and the valve drive chain includes a a cam, a rocker arm and a valve, the valve is arranged There is a valve stem, wherein the brake driving mechanism comprises a brake piston cylinder sleeve and a brake piston, and the brake piston cylinder sleeve is disposed at one end of the rocker arm. The lower side, the brake piston cylinder a brake piston hole is disposed in the lower side of the sleeve, the brake piston is slidably disposed in the brake piston hole, and a brake device positioning hole is disposed in the lower end surface of the brake piston. The brake positioning hole is sleeved on the upper end of the valve stem, and the brake control mechanism controls the non-operating position or the operating position of the brake piston in the brake piston hole.

Further, the brake driving mechanism includes an oil supply mechanism, and the oil supply mechanism includes an oil supply passage and a one-way oil supply valve, and the outlet of the oil supply passage and the brake piston The hole is connected, the one-way oil supply valve is disposed between the oil supply passage and the brake piston hole, or in the oil supply passage, and the oil flow direction of the one-way oil supply is from the oil supply passage into the brake piston hole.

Further, the brake control mechanism includes a hydraulic pressure generating device, and the hydraulic pressure generating device includes a hydraulic control valve and a brake fluid network, and the brake fluid network is in communication with the brake piston hole.

Alternatively, the brake control mechanism includes an exhaust brake, the exhaust brake has a closed position and an open position, in which the exhaust brake interrupts or limits airflow in the exhaust pipe of the engine, This causes the exhaust back pressure of the engine to rise.

Further, the cam includes an enlarged conventional boss and at least one brake boss, and the enlarged conventional valve raised curve formed by the enlarged conventional boss is composed of a bottom portion and a top portion. The bottom of the brake valve is nearly flush with the brake valve rise curve generated by the brake boss, and the top is nearly the same as the conventional valve lift generated by the conventional boss of the engine.

Further, the brake driving mechanism further includes a pre-tensioning spring, and the pre-tensioning spring is disposed in one of the following manners, or adopts a combination of two or more of the following placement modes. To set:

1. One end of the pretensioning spring is placed on the engine, and the other end is placed on the rocker arm;

2. The pretensioning spring is placed between the push rod and the rocker arm of the engine;

3. The preload spring is placed between the brake piston and the brake piston cylinder sleeve - 4. The pretensioning spring is placed between the rocker arm and the brake piston cylinder liner;

5. The pretensioning spring is placed between the valve and the brake piston cylinder liner;

6. The preload spring is placed between the valve and the brake piston.

Further, the brake driving mechanism further includes a valve lift reset mechanism, and the valve lift reset mechanism includes a reset valve and a reset oil passage disposed in the brake piston cylinder sleeve, a reset oil passage is connected to the brake piston hole, the reset valve includes an oil supply position and an oil discharge position, and in the oil supply position, the reset valve closes the reset oil passage, In the oil draining position, the reset valve opens the reset oil passage, and the distance between the rocker arm and the brake piston cylinder sleeve is used to control the opening or closing of the reset valve.

Further, the reset valve is one of the following mechanisms or a combination of any two or more of the following:

1. Sliding plunger valve;

2. Lifting plunger wide door;

3. Lifting ball wide door;

4. Lift column valve; and

5. Other mechanisms that will reset the flow path on and off.

Further, the brake driving mechanism further includes an anti-rotation mechanism, and the anti-rotation mechanism limits the rotation of the movable piston sleeve of the IJ.

Further, the brake drive mechanism further includes a pressure relief mechanism, and the pressure relief mechanism limits the oil pressure in the brake piston bore to a predetermined value.

The working principle of the invention is: when the engine brake is required, the brake control mechanism is opened, and the brake control mechanism controls the brake piston in the brake drive mechanism to move from the retracted non-operating position to the extension in the brake piston bore The operating position. The low-pressure engine oil of the engine supplies oil from the oil supply passage to the brake piston, and locks the brake piston in the operating position. The exhaust valve is driven to open by the extension of the brake piston or by the exhaust back pressure in the exhaust pipe of the engine to generate engine braking. The brake load is transmitted to the cam by the exhaust valve through the brake piston, the brake piston cylinder sleeve and the rocker arm. When the cam rises When the stroke is greater than the lift (brake lift) of the brake boss, the cam drive rocker arm rotates and the brake piston cylinder sleeve is translated, and the distance between the rocker arm and the brake piston cylinder sleeve is reduced, so that the distance between the rocker arm and the brake piston cylinder sleeve is reduced. The valve lift reset valve is opened, and the reset oil passage in the brake piston cylinder sleeve is unloaded. The brake piston is moved from the extended operating position to the retracted inoperative position. The cam rotates past the exhaust boss and returns to the inner base circle, and the braking cycle circulates from the beginning. When the brake control mechanism is closed, the brake piston is always in the retracted non-operating position in the brake piston bore, separated from the normal operation of the engine, the brake cycle ends, the engine exits the brake state, and returns to the ignition state.

The effect of the present invention is positive and significant compared to the prior art. The invention integrates the entire brake mechanism into the existing valve drive chain of the engine, utilizes the wide rod positioning of the valve, has a compact structure, reduces the weight and height of the engine, simplifies the engine brake device, and increases the reliability of the engine operation. Sexuality and durability solve the technical problems existing in the prior art, such as complicated system, heavy structure, large space occupation and brake eccentric load.

DRAWINGS

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a first embodiment of an engine brake device positioned by a valve stem of the present invention in an "off" position of the engine brake.

Figure 2 is a schematic illustration of the first embodiment of the engine brake device positioned by the valve stem of the present invention with the engine brake in the "on" position.

Figure 3 is a schematic illustration of the brake control mechanism of the present invention in the "on" position.

Figure 4 is a schematic illustration of the brake control mechanism of the present invention in the "off" position.

Fig. 5 is a view showing a conventional valve motion curve and an engine brake valve movement curve of the engine exhaust valve of the present invention.

Figure 6 is a schematic illustration of a second embodiment of the engine brake device positioned by the valve stem of the present invention in an "off" position of the engine brake.

Figure 7 is a schematic illustration of a second embodiment of the engine brake device positioned by the valve stem of the present invention with the engine brake in the "on" position.

detailed description Example 1

As shown in Figures 1 and 2, the first embodiment of the engine brake device of the present invention positioned by the valve stem is in its "off" and "open" positions, respectively. There are four main components in Figures 1 and 2, respectively: exhaust valve actuator 200, exhaust valve mechanism 300, engine brake drive mechanism 100, and valve lift reset mechanism 150. The exhaust valve actuator 200 and the exhaust valve mechanism 300 form an exhaust valve drive train.

The exhaust valve actuator 200 includes a cam 230, a cam follower 235 and a rocker arm 210. The rocker arm 210 drives only one exhaust valve 3001 (single rocker arm is open and wide). A valve clearance adjustment system is typically provided at one end of the rocker arm 210 (on the side close to the valve or on the side near the cam). Since the present embodiment employs an overhead cam, the valve clearance adjusting system employs a valve clearance adjusting screw 1 10 disposed on the side of the valve 3001, and the wide-width adjusting screw 110 is fixed to the rocker arm 210 by the locking nut 105. The valve clearance adjusting screw 1 10 is connected to the elephant foot pad 1 14 . The rocker arm 210 is swingably mounted on the rocker shaft 205.

The exhaust valve 3001 is placed over the valve seat 320 in the engine block 500 by a valve spring 3101 to prevent the flow of gas (air during engine braking) between the engine cylinder and the exhaust manifold 600. The exhaust valve actuator 200 transmits the mechanical movement of the cam 230 to the exhaust valve 3001 to be periodically opened and closed.

The cam 230 of the present embodiment has an enlarged boss 220 on the inner base circle 225 which is mainly used for the normal operation of the engine. The enlarged boss 220 is larger than the conventional (without engine brake) exhaust boss. The reason for the increase is that the brake cam is integrated with the conventional cam, and the cam 230 integrated with the conventional cam also has a small boss 232 and a small boss 233 for engine braking. In the conventional (ignition) operation of the engine, in order to skip the brake small boss 232 and the small boss 233, the bottom portion of the enlarged boss 220 must be increased by approximately the same height as the small boss 232 and the small boss 233. The top is equivalent to a conventional exhaust boss. The small boss 232 is used for exhaust gas recirculation during braking, and the small boss 233 is used for compression release. Figure 5 shows in detail the valve lift curve generated by the cam 230.

The brake drive mechanism 100 includes a brake piston cylinder liner 400 and a brake piston 160. Brake piston The cylinder liner 400 is located below the rocker arm 210, and the upper surface of the brake piston cylinder liner 400 abuts against the lower surface of the footpad 14. A brake piston bore 190 is disposed under the brake piston cylinder liner 400. A brake piston 160 is slidably disposed within the brake piston bore 190. A brake device positioning hole 191 is disposed in the lower end surface of the brake piston 160, and the brake device positioning hole 191 is sleeved on the valve stem of the exhaust valve 3001. Therefore, the entire engine brake is positioned by the ceramic rod. The brake piston 160 is movable relative to the upper and lower positions between the inoperative position (Fig. 1) and the operating position (Fig. 2) within the brake piston bore 190. The positioning pin 142 fixed in the brake piston cylinder liner 400 and the limiting groove 137 on the brake piston 160 form a limiting mechanism. The limit mechanism can control the maximum stroke of the brake piston 160. The pressure relief hole 152 may also be added to the limiting groove 137 of the brake piston 160 to form a pressure relief mechanism. When the oil pressure in the brake piston bore 190 is increased, the oil leakage through the gap between the brake piston 160 and the brake piston bore 190, the positioning groove 137 on the brake piston 160, and the pressure relief hole 152 increases. Large, such that the oil pressure on the brake piston 160 does not exceed a predetermined value. A preload spring 198 is disposed between the exhaust rocker arm 2] 0 and the engine. The pretension spring 198 biases the rocker arm 210 against the brake piston cylinder liner 400 such that a brake gap 134 is formed between the cam follower wheel 235 at the other end of the exhaust rocker arm 210 and the inner base circle 225 of the cam 230. The function of the brake gap 134 is to skip the small boss 232 and the small boss 233 above the cam 230 during engine ignition (non-braking) operation.

The preload spring 198 can be a leaf spring and other forms of spring. The pretensioning spring 198 can also use different arrangements, such as between the push rod of the pusher engine and the rocker arm 21 0, the brake piston 160 and the brake piston cylinder liner 400, the rocker arm 21 0 and the brake Between the piston cylinder sleeves 400, between the valve 3001 and the brake piston cylinder liner 400, and between the valve 3001 and the brake piston 160. It can also be a combination of the above arrangements. The preload spring 198 maintains a brake gap 134 (Fig. 1) or 234 (Fig. 2) formed inside the exhaust valve drive train to eliminate non-following and shock inside the exhaust valve drive train.

The brake drive mechanism 100 also includes an oil supply mechanism. The oil supply mechanism includes an oil supply passage and a one-way oil supply valve 172. The one-way oil supply valve 172 is disposed between the oil supply passage and the brake piston hole 190, and may also be installed in the brake piston cylinder liner 400 or even disposed within the oil supply passage. Oil supply passage The one-way oil supply valve 172 supplies oil to the brake piston 160. The oil supply passage includes an axial bore 211 and a radial bore 212 in the rocker shaft 205, a slit 213 and an oil passage 214 in the rocker arm 210, and an oil passage 1 15 in the adjusting screw 110. The outlet of the oil supply passage is connected to the brake piston hole 190. The one-way oil supply 172 allows only the low pressure lubricating oil of the engine to enter the brake piston bore 190 from the oil supply passage.

The reset valve of the valve lift reset mechanism 150 is located between the rocker arm 210 and the brake piston cylinder liner 400, including a reset piston 170, a reset oil passage 412, and a reset oil passage 415 located within the brake piston cylinder liner 400. And a reset screw 1 102 that is secured to the rocker arm 210 by a nut 1052. The overflow area of the reset oil passage 412 or the reset oil passage 415 is smaller than the flow passage area of the oil inlet. The reset oil passage 412 is in communication with the reset oil passage 415, and the reset piston 170 is disposed between the reset oil passage 412 and the reset oil passage 415, and the reset piston 170 is movable between the oil discharge position and the oil supply position. In the drain position (Fig. 1), the reset piston 170 opens the reset oil passage 415, which will be in the oil supply position (Fig. 2), resetting the valve to close the reset oil passage 415.

A valve lift reset mechanism is disposed at the extended portion 2102 of the rocker arm 210. The valve lift reset mechanism includes an adjustment screw 1 102 that is positioned above the reset piston 170 to adjust the reset distance 131 therebetween. The reset distance 131 is designed such that when the reset piston 170 is in the oil drain position (Fig. 1), the adjustment screw 1102 is not touched throughout the rotation period of the cam 230. This greatly reduces the operating frequency of the valve lift reset mechanism 150, increasing reliability and durability.

As shown in FIG. 3, when engine braking is required, the brake control mechanism 50 is opened. The brake control mechanism 50 of the present embodiment is a hydraulic pressure generating device including a hydraulic control valve 51 and a brake fluid network. The brake fluid network is connected to the oil supply passage of the brake drive mechanism 100. That is, the hydraulic control valve 5] supplies oil to the brake drive mechanism 100 through the brake fluid network. The oil enters the brake piston bore 190 through the one-way valve 172. The oil pressure overcomes the force of the pretension spring 198, pushing the brake piston cylinder 400 upward, causing the rocker arm 210 to rotate counterclockwise until the cam follower wheel 235 comes into contact with the inner base circle 225 of the cam 230. The brake gap 134 (Fig. 1) between the cam follower wheel 235 and the inner base circle 225 of the cam 230 is translated into a brake gap 234 (Fig. 2) between the brake piston 160 and the brake piston cylinder liner 400. At the same time, the oil pressure will reset the piston 170 from the drain position Push up to the oil supply position (add spring if necessary) and close the reset oil passage 415. The oil forms a hydraulic link between the brake piston 160 and the brake piston cylinder liner 400.

When the cam 230 is turned from the inner base circle 225 to the brake bosses 232 and 233, the movement of the brake boss is transmitted to the discharge through the exhaust rocker arm 210, the brake piston cylinder liner 400, the hydraulic link 234 and the brake piston 160. The valve 3001 generates a brake valve lift. The cam 230 continues to rotate, and moves upward from the bottom of the enlarged conventional boss 220 to the top, continuing to push the rocker arm 210 to rotate clockwise and the brake piston cylinder 400 to translate downwardly. The reset screw 1 102 on the rocker arm 210 The distance (reset distance) 131 between the reset piston 170 in the brake piston cylinder liner 400 is reduced to zero. The reset screw 1102 pushes the reset piston 170 down within the brake piston cylinder 400 and opens the reset oil passage 415 to unload the oil. The brake piston 160 moves from the extended operating position to the retracted inoperative position within the brake piston cylinder liner 400, and a portion of the enlarged conventional boss 220 of the cam 230 is lost, increasing the conventional The enlarged conventional valve lift curve generated by the boss 220 is reset to the conventional valve lift curve generated by the conventional boss of the engine.

When the cam 230 rotates over the highest position of the enlarged conventional boss 220, moving from the top downward toward the bottom toward the inner base circle 225, the rocker arm 210 rotates counterclockwise, and the brake piston cylinder sleeve 400 translates back up, resetting the screw The reset distance 131 between 1 102 and the reset piston 170 becomes larger. The reset piston 170 is relatively moved upward by the oil pressure in the brake piston cylinder 400, and returns to the oil supply position from the oil discharge position, and the reset oil passage 415 is closed again. The brake piston 160 returns from the retracted inoperative position to the extended operational position within the brake piston cylinder liner 400, re-forming the hydraulic link between the brake piston 160 and the brake piston cylinder liner 400.

The above process forms a braking cycle. This braking cycle is repeated until the brake control mechanism 50 is closed.

As shown in Fig. 4, when the brake control mechanism 50 is closed, the hydraulic control valve 51 discharges oil (three-way solenoid valve) or stops oil supply (if a two-way solenoid valve is used). The valve lift reset mechanism 150 unloads oil once in each engine cycle, the unloaded oil is not replenished, and the hydraulic link between the brake piston 160 and the brake piston cylinder liner 400 is eliminated, and the inside of the valve drive chain is eliminated. The gap 134 is reformed, The movement of the brake boss 232 and the brake boss 233 is skipped and is not transmitted to the exhaust valve 3001, and the braking operation of the engine is released to return to the normal operating state of the engine. The braking cycle is terminated.

As shown in Figures 3 and 4, the brake control mechanism of the present invention is in the "on" and "off" positions, respectively. Since the present invention employs the valve lift reset mechanism 150, the two-position three-way hydraulic control valve 51 in the brake control mechanism 50 can be simplified as a two-way solenoid valve. That is to say, only the oil inlet hole 11 1 is required, and the oil discharge hole 222 is not required.

Fig. 5 is a view showing a conventional valve movement curve and an engine brake valve movement curve of the engine brake valve lift reset device of the present invention. The exhaust valve lift curve in Fig. 5 further illustrates the operation of the first embodiment. There are three valve rise curves in Figure 5:

1. The normal valve lift curve for conventional (ignition) operation of the engine is 220m. The conventional wide-lift curve 220m has a starting point of 225a and an ending point of 225b, and its maximum lift is roughly 220b.

2. For the brake operation of the engine, but without the valve lift reset mechanism, the increased valve lift curve 220v (including the increased conventional wide curve 220e and brake valve lift curves 232v and 233v) The large valve lift curve 220v has a starting point of 225d and an ending point of 225c, and its highest lift is the sum of 220a and 220b. The valve lift curve cycles between 0 and 720 °.

3. Used for the braking operation of the engine with the valve lift curve obtained with the valve lift reset mechanism (thick solid line in the figure). The reset valve rise curve starts at 225d and ends at 225b with a maximum lift of 220b. Therefore, the reset valve lift curve is closed earlier and the lift is lower than the increased valve lift curve 220v.

As shown in Fig. 1, at the time of normal operation of the engine, the bottom of the cam 230 (including the brake boss 232 and the brake boss 233) is skipped due to the gap 134 inside the exhaust valve drive chain, and only the enlarged The top of the conventional boss 220 is transferred to the gas valve 300, producing a conventional valve lift curve 220m (Fig. 5), which is the same as the conventional (without engine brake) valve lift curve of the engine. The transition point of the bottom 220a and the top 220b of the enlarged conventional valve lift curve 220e generated by the enlarged conventional boss 220 is 220t. The height 232p of the bottom portion 220a is the same as or slightly larger than the brake lands 232v and 233v generated by the cam bosses 232 and 233, and the top portion 220b is larger than the conventional valve lift curve 220m. To the same.

When the engine brake is in operation, the mechanical movement of the cam's brake boss 232 and brake boss 233 and the enlarged conventional boss 220 may be transmitted to the exhaust valve 300. However, the broadening curve of the engine brake operation depends on the presence or absence of the valve lift reset mechanism 150. If the engine brake reset mechanism 150 (Figs. 1 and 2) is included, then the engine brake valve rises and no weight before the reset point 220r (between 220t and 220e, greater than the brake valve rises 232v and 233v) The mechanism is the same (Fig. 5). Thereafter, the valve will be lowered from the reset point 220r on the enlarged conventional valve lift curve 220e to the point 220s on the conventional valve lift curve 220m, and finally returned to the valve seat at the end point 225b ( Zero end point), which is much ahead of the end point 225c when there is no valve lift reset mechanism. Therefore, during the top 220b of the increased conventional valve lift curve 220e, the wide lift mechanism 150 reduces the increased conventional valve lift curve 220e to the conventional valve lift curve 220m. This reduces the lift of the valve at the top dead center position of the engine piston at 360 °, avoids the collision of the valve with the piston, increases the braking power, and reduces the temperature inside the cylinder.

Example 2

As shown in Figures 6 and 7, the second embodiment of the engine brake device of the present invention positioned by the valve stem is in its "off" and "open" positions, respectively. The main difference between this embodiment and the first embodiment is the cam 230, the brake control mechanism 50, and the valve lift reset mechanism 150.

The cam 230 of the present embodiment is a conventional engine exhaust cam, and the inner base circle 225 of the cam 230 has only the exhaust boss 220, and no brake boss is added. Therefore, when the engine is operating normally (fire), there is no brake clearance inside the exhaust valve drive train, and there is no need to pre-tension the spring to maintain the clearance. However, a brake spring 1 77 is added between the brake piston 160 and the brake piston cylinder sleeve 400 to assist in opening the exhaust valve 3001 during braking.

The brake control mechanism 50 of the present embodiment includes an exhaust brake device such as an exhaust butterfly 700. The exhaust butterfly valve 700 includes a valve plate 702 that rotates about a valve shaft 704. The drive unit 750 of the brake control mechanism 50 turns off and on the exhaust brake device 700 (such as a butterfly valve) according to a control signal given by the control unit 800. Actuating the reset piston 170 in the valve lift reset mechanism 150 of the present embodiment is a reset spring 2103 that is fastened to the rocker arm 210 by a nut 105. The reset reed 2103 can be a stamped piece having a free end divided into two parts. The intermediate portion 2105 is horizontally rotated at an angle of almost 90 degrees from the vertical direction to form a reset spacing 131 with the reset piston 170. The two portions 2104 continue downwardly to cooperate with the right end surface of the brake piston cylinder liner 400 to form an anti-rotation mechanism that limits the rotation of the brake piston cylinder liner 400. Of course, the anti-rotation mechanism for limiting the rotation of the brake piston cylinder liner 400 may be other methods. For example, a stop pin may be disposed in the brake piston cylinder liner 400 to increase the spring seat of the exhaust valve 3001. The position groove, the stop pin and the stop groove form an anti-rotation mechanism.

When engine braking is required, the brake control mechanism 50 is opened, the exhaust brake device 700 is closed, the airflow within the exhaust tailpipe 710 is interrupted or restricted, and the engine exhaust pipe (including exhaust gas) upstream of the exhaust brake device 700 The exhaust back pressure in the tube 610, the exhaust pipe 620, and the exhaust pipe 630, etc., rises to a predetermined value of the design. This predetermined value is related to engine speed, exhaust valve spring force, and other engine design parameters. When the engine cylinder pressure is low and the exhaust back pressure is high (near the end of the intake stroke, at this time, the exhaust cam 230 is located on the inner base circle 225, and the exhaust rocker arm 210 and the brake piston cylinder liner 400 are relatively stationary. The position of the exhaust back pressure acting on the exhaust valve 3001 overcomes the force of the exhaust valve spring 3101 and the cylinder pressure, causing the exhaust valve 3001 to rebound a small amount to open 330 (Fig. 7). The brake piston 160 located on the exhaust valve 3001 follows the exhaust valve 3001 in the brake piston bore 190 and moves downward from the retracted inoperative position (Fig. 6) to the extended operating position (Fig. 7). A brake gap 234 is formed between the moving piston 160 and the brake piston cylinder liner 400. The low-pressure engine oil of the engine enters the brake piston bore 190 from the oil supply passage through the one-way oil supply wall 1 72, filling the brake gap 234. The oil pressure simultaneously pushes the reset piston 170 upward from the oil discharge position to the oil supply position, and closes the reset oil passage 415. A hydraulic link is formed between the brake piston 160 and the brake piston cylinder liner 400. The brake piston 160 is hydraulically locked in the extended operating position, and the inner exhaust valve 3001 that opens the reverse jump is held against the falling. Return to valve seat 320. From the end of the intake stroke of the engine, through the entire compression stroke and most of the power stroke, the inner exhaust valve 3001 is always kept at a small constant opening (gap 330), resulting in a deflated engine brake. The brake load is transmitted from the inner exhaust valve 3001 through the brake piston 160, hydraulic link 234. The brake piston cylinder liner 400 and the rocker arm 210 are transmitted to the cam 230 at the position of the inner base circle 225. When the cam 230 is turned from the inner base circle 225 to the conventional exhaust boss 220, the cam 230 drives the rocker arm 210 to rotate clockwise and the brake piston cylinder sleeve 400 to move downward. The distance (reset distance) 131 between the horizontal section 2105 of the reset reed 2103 and the reset piston 170 is reduced to zero. The reset piston 170 is pushed down within the brake piston cylinder liner 400, opening the reset oil passage 415 to unload oil. The brake piston 160 moves from the extended operating position to the retracted inoperative position within the brake piston cylinder liner 400 (the force of the exhaust valve spring 31 01 is much greater than the brake spring 177) due to valve bounce The part of the brake valve is lost and returns to the normal valve lift curve.

The cam 230 is rotated past the conventional exhaust boss 220, back to the inner base circle 225, and the braking cycle begins from the beginning and is repeated until the brake control mechanism 50 is closed. At this time, the exhaust brake device 700 (butterfly valve) is opened, the airflow in the exhaust tail pipe 710 is not restricted, and the engine exhaust pipe upstream of the exhaust brake device (the exhaust pipe 610, the exhaust pipe 620, and the exhaust pipe) The exhaust back pressure in the tube 630, etc. is lowered, the exhaust valve cannot be reversely opened (the force of the exhaust valve spring 3101 is much larger than the brake spring 177), and the brake piston 160 is retracted in the piston hole of the wide bridge. The non-operating position (Fig. 6), the engine exits the braking state and returns to the ignition state.

The many specific embodiments described above should not be considered as limiting the scope of the invention, but rather as a specific example of the invention, many other variations are possible. For example, the engine brake device and method proposed by the present invention can be used not only for an overhead cam engine but also for a pusher engine; not only can generate a deflated engine brake (including partial cycle and full cycle deflation) Type engine brakes) can also produce compression-release engine brakes (with and without exhaust gas recirculation).

In addition, the way the engine brakes are carried can also be different. It can be hydraulic, that is to say, hydraulically linked, like the conventional hydraulic engine brakes; it can also be solid-chain, that is, mechanically linked by solids.

Also, the reset valve of the valve lift reset mechanism may take different forms, including a lift plunger valve or a sliding plunger valve formed by a reset piston, and a lift ball formed by a reset valve ball. Valve or lift column valve, and other mechanisms that will reset the flow path on and off. These reset wide doors can be used interchangeably if needed.

In addition, whether it is a compression-release engine brake or a deflated engine brake, the reset position of the exhaust valve lift is at the top of the valve lift, that is, above the brake lift.

Also, the exhaust brake of the brake control mechanism may be not only an exhaust butterfly valve but also other types of current limiting devices such as a variable geometry turbocharger. As long as it can increase the exhaust back pressure function of the engine.

In addition, the one-way fuel supply valve may be a ball valve or other types of valves, such as a disc valve. The one-way fuel supply valve can also be installed in different positions.

Also, brake pistons can be varied, such as "H" and "T".

Therefore, the scope of the invention should not be determined by the specific examples described above, but by the claims.

Claims

claims

1. An engine braking device positioned by a valve stem, including a brake drive mechanism and a brake control mechanism provided on the engine. The engine includes a valve drive chain, and the valve drive chain includes a A cam, a rocker arm and a valve, and a valve stem is provided in the valve, characterized in that: the brake drive mechanism includes a brake piston cylinder liner and a brake piston, and the brake piston cylinder liner It is arranged on the lower side of one end of the rocker arm, and a brake piston hole is provided on the lower side of the brake piston cylinder liner. The brake piston is slidably arranged in the brake piston hole. A braking device positioning hole is provided in the lower end surface of the moving piston. The braking device positioning hole is sleeved on the upper end of the valve stem. The braking control mechanism controls the braking piston in the braking piston hole. non-operating position or operating position.

2. The engine braking device positioned by the valve wide rod as claimed in claim 1, characterized in that: the brake driving mechanism includes an oil supply mechanism, and the oil supply mechanism includes an oil supply channel and One-way oil supply valve, the outlet of the oil supply channel is connected to the brake piston hole, the one-way oil supply valve is arranged between the oil supply channel and the brake piston hole, or in the oil supply channel , the oil flow direction of the one-way oil supply valve is from the oil supply channel into the brake piston hole.

3. The engine braking device positioned by the valve stem according to claim 1, characterized in that: the brake control mechanism includes a hydraulic pressure generating device, and the hydraulic pressure generating device includes a hydraulic control valve and a brake. Fluid network, the brake fluid network is connected with the brake piston hole.

4. The engine braking device positioned by the valve stem as claimed in claim 1, characterized in that: the braking control mechanism includes an exhaust brake, and the exhaust brake has a closed position and an open position. , in the closed position, the exhaust brake interrupts or restricts the air flow in the engine exhaust tail pipe, causing the engine exhaust back pressure to increase.

5. The engine braking device positioned by the valve wide rod as claimed in claim 1, characterized in that: the cam contains an enlarged conventional boss and at least one braking boss, and the enlarged The enlarged conventional valve lift curve generated by the conventional boss is composed of a bottom and a top. The bottom is close to the same height as the brake valve lift curve generated by the brake boss, and the top is at the same height as the brake valve lift curve generated by the brake boss. The conventional boss of the machine generates nearly the same lift as conventional valves.

6. The engine brake device positioned by the valve stem as claimed in claim 1, characterized in that: the brake drive mechanism further includes a preload spring, and the preload spring adopts the following placement method: One way to set it up, or a combination of two or more of the following placement ways:

1. One end of the preload spring is placed on the engine, and the other end is placed on the rocker arm;

2. The preload spring is placed between the push rod and rocker arm of the engine;

3. The preload spring is placed between the brake piston and the brake piston cylinder liner;

4. The preload spring is placed between the rocker arm and the brake piston cylinder liner;

5. The preload spring is placed between the valve and the brake piston cylinder liner;

6. The preload spring is placed between the valve and the brake piston.

7. The engine braking device positioned by the valve stem as claimed in claim 1, characterized in that: the brake drive mechanism further includes a valve lift reset mechanism, and the lift reset mechanism includes a reset mechanism. The valve and the reset oil passage provided in the brake piston cylinder liner, the reset oil passage is connected with the brake piston hole, and the reset wide door contains an oil supply position and an oil discharge position. position, at the oil supply position, the reset valve closes the reset oil passage, and at the oil discharge position, the reset valve opens the reset oil passage, using the rocker arm and the brake piston cylinder The distance between the sets controls the opening or closing of the reset valve.

8. The engine braking device positioned by the valve stem as claimed in claim 7, characterized in that: the reset valve is one of the following mechanisms or a combination of any two or more mechanisms:

1. Sliding plunger valve;

2. Lifting plunger wide door;

3. Lift ball valve;

4. Lifting column valve; and

5. Open and close the mechanism to reset the flow path.

9. The engine braking device positioned by the valve stem as claimed in claim 1, characterized in that: The brake driving mechanism also includes an anti-rotation mechanism, and the anti-rotation mechanism limits the rotation of the brake piston cylinder liner.

10. The engine braking device positioned by the valve stem as claimed in claim 1, characterized in that: the brake driving mechanism further includes a pressure relief mechanism, and the pressure relief mechanism limits the brake piston. The oil pressure in the hole is the designed predetermined value.