Abstract:
A fixed chain engine braking device includes a brake box, a driving mechanism and a braking mechanism. One upright blind hole and one horizontal blind hole are placed in the brake box, and the upright blind hole intersects the horizontal blind hole orthogonally. The driving mechanism includes a rolling ball and/or a driving piston placed in the horizontal blind hole, the braking mechanism includes a braking plunger placed in the upright blind hole. A fluid passage is placed in the brake box, and the fluid passage is communicated with the entry of the horizontal blind hole.

Description:
FIELD OF THE INVENTION 
       [0001]    The present application relates to the mechanical field, specifically to an engine brake device, and particularly to a mechanical linkage engine brake device. 
       BACKGROUND OF THE INVENTION 
       [0002]    It is well known in the prior art to use an internal combustion engine as a brake means by converting the engine temporarily to an air compressor. The conversion starts by cutting off the provision of the fuel, opening the exhaust valve(s) at or near the end of the compression stroke of the engine piston, and allowing the compressed gases (air during braking) to be released. The energy absorbed by the compressed gas during the compression stroke of the engine can not be transmitted to the engine piston through the subsequent expansion stroke, but is dissipated by the exhaust and cooling systems of the engine, resulting in an effective engine braking. Thereby the vehicle is slowed down. 
         [0003]    An example of the engine brake device is disclosed in U.S. Pat. No. 3,220,392 by Cummins, and an engine brake system based on the patent has achieved a great commercial success. However, this kind of engine brake system is a bolt-on accessory mounted at the top of the engine. In order to mount this kind of brake system, a spacer is additionally provided between the cylinder head and the valve cover, which adds unnecessary height, weight and costs to the engine. The above problems occur due to the fact that the engine brake system is employed as an accessory to, rather than an integrated part of, the engine. 
         [0004]    The prior engine brake transmits the mechanical input to the exhaust valve(s) to be opened through a hydraulic circuit. A master piston reciprocating in a master piston bore is located in the hydraulic circuit. The reciprocating motion is provided by the mechanical input of the engine, such as the rocking of the injector rocker arm. The motion of the master piston is transmitted, through hydraulic fluid, to a slave piston located in the hydraulic circuit, causing the slave piston to reciprocate in a slave piston bore. The slave piston acts, directly or indirectly, on the exhaust valve(s), generating the valve event for the engine braking operation. 
         [0005]    Therefore, the conventional hydraulic-driven engine brake has another drawback due to the compliance or deformable of the hydraulic system, which is relevant to the flexibility of the fluid. High flexibility of the fluid greatly reduces the brake valve lift. The reduction of the brake valve lift leads to the increase of the braking load, which in turn causes a higher flexibility, thereby forming a vicious circle. In addition, the brake valve lift reduction caused by the hydraulic deformation increases with the increase of the engine speed, which is against the engine braking performance requirement that higher engine speed needs higher brake valve lift. In order to reduce the hydraulic flexibility, a large diameter hydraulic piston is needed, which increases the volume and weight as well as the time of oil refill or discharge for extending or retracting such a large diameter piston. That is to say, a large diameter hydraulic piston will increase the momentum of inertia and response time of the engine brake system. 
       SUMMARY OF THE INVENTION 
       [0006]    The purpose of the present application is to provide a mechanical linkage engine brake device to solve the technical problems of the prior hydraulic-driven engine brake system, for example, the increased height and weight of the engine, the increased system complexity and inertia of the engine brake system, and the slow response of the engine brake system. 
         [0007]    The mechanical linkage engine brake device according to the present application includes a brake housing, an actuation mechanism and a brake mechanism. The brake housing is provided therein with an upright blind bore and a horizontal blind bore perpendicularly intersecting the upright blind bore. The actuation mechanism includes a ball or an actuation piston, or a ball-piston combination. The brake mechanism includes a brake plunger. The ball, or the actuation piston, or the ball-piston combination is disposed in the horizontal blind bore. The brake plunger is disposed in the upright blind bore. The brake housing is provided therein with a fluid passage in communication with an entrance of the horizontal blind bore. An outer diameter of the ball or the actuation piston, or an outer diameter of the ball-piston combination matches an inner diameter of the horizontal blind bore. The brake plunger has an upper limit position and a lower limit position in the upright blind bore. In the upper limit position, a top of the brake plunger stands in the horizontal blind bore; and in the lower limit position, the top of the brake plunger stands outside of the horizontal blind bore. 
         [0008]    Further, the actuation mechanism includes a return spring, which has one end acting on the brake housing and the other end acting on the actuation piston or on the ball-piston combination. 
         [0009]    Further, a liquid seal is formed between the actuation piston and the horizontal blind bore. 
         [0010]    Further, the actuation mechanism further includes a ball. One side of the ball is in contact with the actuation piston, while the other side of the ball is in contact with the return spring. 
         [0011]    Further, the actuation mechanism includes a return piston. The return piston is disposed in the horizontal blind bore and is pressed against the ball by the return spring. A liquid seal is formed between the return piston and the horizontal blind bore. 
         [0012]    Further, the return piston has a decompression and bleeding orifice communicating with the horizontal blind bore and a space outside the brake housing. 
         [0013]    Further, the actuation mechanism includes two return springs provided in the horizontal blind bore, and the two return springs are arranged at opposite sides of the ball. 
         [0014]    Further, the upright blind bore is provided therein with a brake spring, the brake spring being provided between a lower end of the brake plunger and the brake housing. 
         [0015]    Further, a position limiter is provided between the brake plunger and the upright blind bore. 
         [0016]    Further, the position limiter includes a groove and a stop pin, wherein the groove is formed in a central portion of an outer surface of the brake plunger and is extended axially, the stop pin is fixedly provided in a middle portion of an inner wall of the upright blind bore. A length of the groove is larger than a diameter of the stop pin, and the stop pin is located in the groove. 
         [0017]    Further, an upper end of the brake plunger is provided with a brake transition surface and a brake bearing surface. Each of the brake transition surface and the brake bearing surface is a flat surface including a stepped surface and an inclined surface, or a conical surface, or an arc surface, or a cylindrical surface, or a spherical surface, or a combination of two or more of the above-mentioned surfaces. 
         [0018]    Further, one end of the actuation piston is provided with a brake actuation surface. The brake actuation surface is a flat surface including an inclined surface, or a conical surface, or an arc surface, or a cylindrical surface, or a spherical surface, or a combination of two or more of the above-mentioned surfaces. 
         [0019]    Further, the brake housing includes at least one of the following:
       a dedicated bolt-on brake housing,   a dedicated brake rocker arm,   an engine exhaust rocker arm, and   an engine valve bridge.       
 
         [0024]    The operation principle of the present application is: when it needs to convert the state of the engine from the normal operation to the engine braking operation, the engine brake controller is turned on to supply oil to the fluid passage in the brake housing through a brake fluid passage. The actuation piston or the ball is pushed, overcoming the actions of the returning spring and the braking spring, to the right along the horizontal blind bore under the pressure of the oil, such that the brake plunger is moved downwards in the upright blind bore. Thereby the engine brake is switched from the inoperative position to the operative position, and the engine is converted from the normal operation to the engine braking operation. When it does not need the engine braking operation, the engine brake controller is turned off to drain the oil, such that no oil pressure is applied to the actuation piston or the ball, thereby the actuation piston or the ball is moved to the left under the action of the return spring until the actuation piston is stopped against the left end surface of the horizontal blind bore. The brake plunger is moved upwards in the upright blind bore under the force of the brake spring. The engine brake is switched from the operative position to the inoperative position, and the engine is free of the influence of the engine brake and can operate normally. 
         [0025]    The present application has many advantageous technical effects over the prior art. The present application does not employ a hydraulic brake control valve, which simplifies the design, reduces the cost and the braking response time. The present application does not employ liquid to carry the braking load, and therefore can avoid problems, such as leakage, deformation or load fluctuation caused by high oil pressure and temperature. The brake valve lift can be designed with a smaller value because it is not affected by oil temperature, oil pressure and air content in oil, which allows a smaller clearance between the engine piston and valve. Also the mechanical linkage engine brake device of the present application can be integrated into the engine to reduce the height, the size and the weight of the engine brake. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIG. 1  is a schematic diagram of a first embodiment of the present application at the “off” position; 
           [0027]      FIG. 2  is a schematic diagram of the first embodiment of the present application at the “on” position; 
           [0028]      FIG. 3  is a schematic diagram of a second embodiment of the present application at the “off” position; 
           [0029]      FIG. 4  is a schematic diagram of the second embodiment of the present application at the “on” position; 
           [0030]      FIG. 5  is a schematic diagram of a third embodiment of the present application at the “off” position; 
           [0031]      FIG. 6  is a schematic diagram of the third embodiment of the present application at the “on” position; 
           [0032]      FIG. 7  is a schematic diagram of a fourth embodiment of the present application at the “off” position; 
           [0033]      FIG. 8  is a schematic diagram of the fourth embodiment of the present application at the “on” position; 
           [0034]      FIG. 9  is a schematic diagram of an application of the fourth embodiment of the present application; 
           [0035]      FIG. 10  is a schematic diagram of a fifth embodiment of the present application at the “off” position; 
           [0036]      FIG. 11  is a schematic diagram of the fifth embodiment of the present application at the “on” position; 
           [0037]      FIG. 12  is a schematic diagram of a sixth embodiment of the present application at the “off” position; and 
           [0038]      FIG. 13  is a schematic diagram of the sixth embodiment of the present application at the “on” position. 
       
    
    
     DETAILED DESCRIPTION 
     First Embodiment 
       [0039]    As shown in  FIG. 1  and  FIG. 2 , the mechanical linkage engine brake device  100  according to the present application includes a brake housing  2102 , an actuation mechanism and a brake mechanism. The brake housing  2102  is provided therein with an upright blind bore  190  and a horizontal blind bore  260  that intersect each other. The actuation mechanism includes an actuation piston  164  and a ball  175 . The actuation piston  164  and the horizontal blind bore  260  form a liquid seal. One end of the actuation piston is in contact with the ball to form a linkage. The brake mechanism includes a brake plunger  160 . As shown in  FIG. 1 , the actuation piston  164  and the ball  175  are disposed in the horizontal blind bore  260  in the brake housing  2102 , and are pushed to the left by a return spring  156  to thereby abut against the end surface  246  of the piston bore  260  at normal state. One end of the return spring  156  is on the ball  175  of the actuation mechanism while the other end thereof is on the spring seat  158 . The spring seat  158  is positioned by a retaining ring  157  fixedly connected on the brake housing  2102 . The spring seat  158  has a venting hole  168 . The brake plunger  160  is disposed in the upright blind bore  190  in the brake housing  2102 . The upper end of the brake plunger has a brake transition surface  126  and a brake bearing surface  128 . The brake transition surface  126  is a conical surface but may also be a flat surface (including a stepped surface and an inclined surface), or an arc surface, or a cylindrical surface, or a spherical surface, or a combination of two or more of the above-mentioned surfaces. Similarly, the brake bearing surface  128  may be a flat surface (including a stepped plane and an inclined plane), or a conical surface, or an arc surface, or a cylindrical surface, or a spherical surface, or a combination of two or more of the above-mentioned surfaces. One end of a brake spring  177  is provided at the lower end of the brake plunger  160 , while the other end thereof is fixedly connected on the brake housing  2102  by a screw  179 . As shown in  FIG. 1 , under the action of the spring  177 , the brake transition surface  126  of the brake plunger  160  is stopped against the lower right side of the ball  175 . 
         [0040]    The brake mechanism further includes a position limiter for the brake plunger  160 , including a stop pin  142  fixedly provided in the brake housing and a groove  137  in the brake plunger  160 . The position limiter may also be formed in other ways, such as by using stepped surfaces. 
         [0041]    The work process of the present embodiment is as follows: when it needs to convert the state of the engine from the normal operation ( FIG. 1 ) to the engine braking operation ( FIG. 2 ), an engine brake controller (not shown) is turned on to supply oil to the actuation mechanism of the mechanical linkage engine brake device  100  through a braking fluid passage including a fluid passage  214  in the brake housing  2102 . The actuation piston  164  and the ball  175  are pushed, overcoming the force of the return spring  156 , to the right under the pressure of the oil. The ball  175  is pushed to press the brake transition surface  126  on the upper end of the brake plunger  160  to overcome the action of the brake spring  177 , such that the brake plunger  160  is pushed downwards along the upright blind bore  190  from an inoperative position to an operative position. At the same time, the ball  175  is moved from the brake transition surface  126  to the brake bearing surface  128  at the upper end of the brake plunger  160  ( FIG. 2 ). 
         [0042]    When it does not need the engine braking operation, the engine brake controller is turned off to drain the oil, such that no oil pressure is applied to the actuation piston  164  and the ball  175 , thereby the actuation piston  164  and the ball  175  are moved to the left under the force of the return spring  156  and are stopped against the left end surface  246  of the horizontal blind bore  260 . The brake plunger  160  is pushed, under the force of the brake spring  177 , upwards in the upright blind bore  190 , such that the brake transition surface  126  at the upper end is stopped against the lower right side of the ball  175 . Thereby the brake plunger is back to the inoperative position ( FIG. 1 ), and the engine is free from the influence of the brake plunger and can operate normally. 
       Second Embodiment 
       [0043]    As shown in  FIG. 3  and  FIG. 4 , the second embodiment is a variation of the first embodiment. The actuation piston  164  and the ball  175  in the first embodiment are combined into one body. The left part of the body is part of the actuation piston  164  that provides guide and seal, while the right part of the body is the actuation surface  163  of a spherical shape (which may also be a cone surface or other surfaces). 
       Third Embodiment 
       [0044]    As shown in  FIG. 5  and  FIG. 6 , the third embodiment is also a variation of the first embodiment. Compared with the first embodiment, the actuation piston in the first embodiment is eliminated, and a return piston  162  that forms a liquid seal with the horizontal blind bore  260  is further provided. The return piston  162  is provided with a decompression hole  122  and a bleeding orifice  168  (which may also be a combined cone-shaped decompression and bleeding orifice). The return piston  162  functions together with the return spring  156 . The return spring  156  forces the return piston  162  against the ball  175  such that the decompression hole  122  is closed and to ensure that the ball  175  is always in close contact with the return piston  162 . 
         [0045]    The present embodiment operates as follows: when it need to convert the state of the engine from the normal operation (see  FIG. 5 ) to the engine braking operation ( FIG. 6 ), the engine brake controller (not shown) is turned on to supply oil to the actuation mechanism of the engine brake device  100  through the brake fluid passage including the fluid passage  214  in the brake housing  2102 . The ball  175  is firstly pushed, overcoming the force of the return spring  156 , under the action of the oil. At the same time, the oil flow passes the ball (through the gap between the ball and the bore or an axial groove not shown in the Figure), and pushes, overcoming the force of the brake spring  177 , the brake plunger  160  downwards along the upright blind bore  190 . The maximum downward stroke of the brake plunger  160  is determined by the position limiter (the stop pin  142  and the groove  137 ). The ball  175  is pressed against the return piston  162 , and the two move together to the right until the return piston  162  is stopped by the spring seat  158 . At this point, the ball  175  is moved onto the brake bearing surface  128  on the top of the brake plunger  160 , and the brake plunger  160  is moved downwards to the operative position as shown in  FIG. 6 . 
         [0046]    When it does not need the engine braking operation, the engine brake controller is turned off to drain the oil such that no oil pressure is applied to the return piston  162  and the ball  175 , thereby the return piston  162  and the ball  175  are moved to the left by the return spring  156  and are stopped against the left end surface  246  of the horizontal blind bore  260 . The brake plunger  160  is moved upwards in the upright blind bore  190  by the brake spring  177 , such that the brake transition surface  126  at the upper end is stopped against the lower right side of the ball  175 . Thereby the brake plunger is back to the inoperative position ( FIG. 5 ) and is separated from the normal engine operation. 
       Fourth Embodiment 
       [0047]    As shown in  FIG. 7 ,  FIG. 8  and  FIG. 9 , the present embodiment, compared with the third embodiment, only is further provided with a brake valve lash adjusting screw  1102  that is fixedly connected on the brake housing  2102  by a lock nut  1052 . The operation principle of the fourth embodiment is similar to that of the third embodiment. 
         [0048]      FIG. 9  is a schematic diagram illustrating an application of the present embodiment. The brake housing  2102  of the engine brake device  100  is a dedicated brake rocker arm of a dedicated exhaust valve actuator  2002  for engine braking. The dedicated exhaust valve actuator  2002  further includes a brake cam  2302 , a cam follower  2352  and a rocker brake spring  1982 . The brake cam  2302  is merely provided, on the inner base circle  2252  thereof, with the small cam lobes  232  and  233  for engine braking. 
         [0049]    The normal operation of the engine exhaust valves  300  is driven by an engine exhaust valve system or an engine exhaust valve actuator  200 . The exhaust valve actuator  200  includes many components, including a cam  230 , a cam follower  235 , a rocker arm  210 , a valve bridge  400 , and exhaust valves  300 . The exhaust valves  300  are biased, by engine valve springs  3101  and  3102 , against the valve seats  320  in the engine cylinder block  500 , to prevent gas flow between the engine cylinder and the exhaust manifold  600 . The rocker arm  210  is rotationally installed on the rocker shaft  205 , passing the motion of the cam  230  to the exhaust valves  300  for their cyclic opening and closing. The exhaust valve system may also include other components, such as a valve lash adjusting screw and an e-foot, etc., which are omitted herein for brevity. The cam  230  has a large cam lobe  220  on the inner base circle  225  thereof to produce the main valve lift profile for the normal engine operation. 
         [0050]    When it needs to convert the state of the engine from the normal operation to the engine braking operation, the engine brake controller (not shown) is turned on to supply oil to the engine brake device  100  through the brake fluid passage that includes a fluid passage  211  and a radial hole  212  in the rocker arm shaft, a groove  213  and a fluid passage  214  in the rocker arm. The ball  175  together with the return piston  162  is pushed, overcoming the forces of the brake spring  177  on the brake plunger  160  and the return spring  156  successively, to the right under the action of the oil, such that the brake plunger  160  is moved from the retracted position (shown in  FIG. 7 ) to the extended position (shown in  FIG. 8 ). The stroke of the brake plunger eliminates the gap  132  between the brake plunger  160  and the brake rod  116  (shown in  FIG. 9 ). The motion of the small cam lobes  232  and  233  of the brake cam  2302  is transmitted to the exhaust valve  3001  through the rocker arm  2102 , the brake valve lash adjusting screw  1102 , the ball  175 , the brake plunger  160  and the brake rod  116 , for engine braking. 
         [0051]    When it does not need the engine braking operation, the engine brake controller is turned off to drain the oil, such that no oil is applied to the ball  175  and the return piston  162 , thereby the ball  175  and the return piston  162  are moved to the left under the action of the return spring  156  until the ball  175  is stopped against the end surface  246  of the horizontal blind bore  260  ( FIG. 7 ). The brake plunger  160  is moved upwards in the upright blind bore  190  to the inoperative position, forming the gap  132  with the brake rod  116  (shown in  FIG. 9 ). Thereby the engine is free from the influence of the engine brake device  100  and can operate normally. 
         [0052]    In addition to the dedicated brake rocker arm, the brake housing  2102  of the engine brake device  100  may be a dedicated bolt-on brake housing (box), the exhaust rocker arm of the engine, or the valve bridge of the engine. 
       Fifth Embodiment 
       [0053]    As shown in  FIG. 10  and  FIG. 11 , the fifth embodiment is a variation of the third embodiment. The ball and the return piston are combined into one actuation piston. The right part of the actuation piston  164  functions as a guide and forms a liquid seal with the horizontal blind bore, while the left part is the actuation surface of a spherical shape (it may be of other shapes including a stepped surface, or an inclined surface, or a conical surface, or an arc surface, or a cylindrical surface, or a combination of two or more of the above-mentioned surfaces). The central part is a spherical surface  163  which may also be a conical surface. The operation principle of the present embodiment is similar to that of the third embodiment and detailed description thereof is omitted. 
       Sixth Embodiment 
       [0054]    As shown in  FIG. 12  and  FIG. 13 , compared with the third embodiment, the sixth embodiment is additionally provided with a return spring  166 . One end of the return spring  166  is on the brake housing  2102 , while the other end thereof is on the ball  175  of the actuation mechanism. The force of the return spring  166  is smaller than that of the return spring  156  such that when no oil pressure is applied, the ball  175  can be stopped against the shoulder  246  at the left end of the horizontal blind bore  260 . At the same time, there is no decompression orifice or bleeding orifice (or a combined decompression and bleeding orifice) in the return piston  162 . The operation principle of the present embodiment is similar to that of the third embodiment and detailed description thereof is omitted. 
         [0055]    While the above description describes some embodiments, these embodiments should not be regarded as limitations to the scope of the present application, but are exemplifications of the preferred embodiments thereof. Many other variations are likely to be derived. For instance, the return spring and the brake spring herein may be of a cylindrical type, a leaf type, and a wave form, etc., and may also be installed or positioned at different places or orientations. In addition, the position limiter of the brake plunger may also be other forms. Accordingly, the scope of the present application should not be determined by the embodiments illustrated, but is determined by the claims and their legal equivalents.