Abstract:
A decompression device for an internal combustion engine comprises a valve rocker shaft bracket and a valve rod. A valve spring is sleeved on the valve rod, and above the valve rod a valve rocker is arranged. The valve rocker shaft bracket is connected to a decompression bracket. The valve rocker is movably connected to a valve opening/closing device connected with a control device. When the internal combustion engine is started, the valve opening/closing device receives a control command from the control device to keep connecting with the valve rocker for a time, and then disconnect, so that the valve rod arrives at the valve closing position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a national phase entry under 35 U.S.C 371 of International Patent Application No. PCT/CN2013/086304, filed Oct. 31, 2013, which claims the priority from Chinese Application Nos. 201210461057.2 filed Nov. 6, 2012 and 201320090085.8 filed Feb. 5, 2013, all of which are hereby incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to the field of starting technology of internal combustion engine, and particularly relates to a decompression device for an internal combustion engine. 
     BACKGROUND OF THE INVENTION 
     An internal combustion engine is difficult to start, in particular, the problem of a starting system of a high-power diesel engine is more prominent, the failure rate is high, the reliability is poor, in order to solve this problem, people always increase the power of a starter and a storage battery, although the internal combustion engine can be started in this way, since the starting torque of the internal combustion engine still exists, a starting current larger than 1000 A still exists, such that the high failure rate of the starting system cannot be solved fundamentally. 
     In order to reduce the starting torque of the internal combustion engine, people design a manual decompression starting device on a low-power internal combustion engine, before the internal combustion engine is started, firstly a valve is manually opened to ensure no compression resistance of the internal combustion engine, and after a crankshaft reaches a starting speed, the valve is manually closed, the shortcoming of this method is that both-hand operation is needed, thus being inconvenient to use, and in addition, the valve of a high-power multi-cylinder internal combustion engine requires a very large acting force to be opened manually, therefore the high-power multi-cylinder internal combustion engine is provided with no manual decompression device. 
     In order to change the manual decompression starting of the internal combustion engine into automatic decompression starting, people propose methods of acting on the valve by air pressure, hydraulic pressure and an electromagnet, but these methods have the shortcomings that a decompression structure occupies a large space, the necessary mechanical force and external electric force are large, numerous components are needed and failure is prone to occur. 
     SUMMARY OF THE INVENTION 
     To achieve automatic control during decompression starting of an internal combustion engine, ensure simple structure and few components and achieve high reliability, the present invention provides an inserted cushion block type decompression device for an internal combustion engine. 
     To achieve the above object, the present invention adopts the following technical solutions: 
     a decompression device for an internal combustion engine, including a valve rocker shaft bracket and a valve rod, wherein a valve spring is sleeved on the valve rod, a valve rocker is arranged above the valve rod, and the valve rocker shaft bracket is connected to a decompression bracket; the valve rocker is movably connected to a valve opening/closing device connected with a control device; the valve opening/closing device is a device that, when the valve rocker moves downwards before the internal combustion engine is stopped, the valve opening/closing device receives a control command from the control device to connect with the valve rocker, so that the valve rod can not arrive at a valve closing position, and the valve is at an open state; when the internal combustion engine is started, the valve opening/closing device receives a control command from the control device to keep connecting with the valve rocker for a time, and then disconnect, so that the valve rod arrives at the valve closing position; the control device is a device which sends a command to the valve opening/closing device to keep connecting or disconnecting with the valve rocker. 
     The valve opening/closing device includes a decompression shaft located above the valve rocker, and the decompression shaft is in movable fit with the decompression bracket; a decompression cushion block is sleeved on the decompression shaft, springs are respectively arranged at the two ends of the decompression cushion block, a spring limiting device is arranged at the outside of each spring, and the lengths and elastic forces of the two springs are consistent; the control device is a time-delay relay; an electromagnet is fixed on a valve chamber cover, a movable iron core of the electromagnet is connected with the decompression shaft, the operation of the electromagnet is controlled by the time-delay relay, and when the internal combustion engine is stopped, the decompression cushion block is located between the decompression shaft and the valve rocker. 
     The spring limiting device is a snap spring. 
     The spring limiting device includes a shifting fork shaft and a shifting fork on the shifting fork shaft, and the shifting fork limits the springs; the movable iron core of the electromagnet is connected with the decompression shaft through the shifting fork shaft and the shifting fork. 
     The valve opening/closing device includes an electromagnet fixed on the decompression bracket; the control device is a time-delay relay; the action of the electromagnet is controlled by the time-delay relay, and when the internal combustion engine is stopped, the movable iron core is located between the decompression bracket and the valve rocker. 
     The valve opening/closing device includes a hydraulic cylinder fixed on the decompression bracket; the control device is a time-delay relay; the action of a piston of the hydraulic cylinder is controlled by the time-delay relay, and when the internal combustion engine is stopped, the piston is located between the decompression bracket and the valve rocker. 
     The valve opening/closing device includes an electromagnet fixed on the decompression bracket; the control device is a time-delay relay; the action of the electromagnet is controlled by the time-delay relay, a valve cap is installed at the upper end of the valve rod, and when the internal combustion engine is stopped, the movable iron core is located between the decompression bracket and the valve cap. 
     The valve opening/closing device includes a supporting block and a decompression fulcrum bar driving mechanism, which are fixed at the upper part of a cylinder cover and at the lower part of the valve rocker, the decompression fulcrum bar driving mechanism is connected with a decompression fulcrum bar, and the decompression fulcrum bar is driven by the decompression fulcrum bar driving mechanism to achieve the extension and retraction of the decompression fulcrum bar. 
     By adopting the above-mentioned technical solutions in the present invention, the occupied space of the decompression starting device is reduced, so that the decompression starting device not only can be well suitable for commercial vehicles, but also can be better installed on passenger cars for use, to achieve automatic control during decompression starting of the internal combustion engines of the passenger cars, moreover, the structure is simple, the components are few, and high reliability is achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a structure of embodiment 1 of the present invention. 
         FIG. 2  is a schematic diagram of a structure of embodiment 2 of the present invention. 
         FIG. 3  is a schematic diagram of a structure of embodiment 3 of the present invention. 
         FIG. 4  is a schematic diagram of a structure of embodiment 4 of the present invention. 
         FIG. 5  is a schematic diagram of a structure of embodiment 5 of the present invention. 
         FIG. 6  is a view in an A-A direction of  FIG. 5 . 
         FIG. 7  is a front view of embodiment 6 of the present invention. 
         FIG. 8  is a top view of embodiment 6 of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiment 1 
     In  FIG. 1 , a valve rocker shaft bracket  1 , a valve rocker  5 , a valve rod  11  and a valve spring  12  are original parts of an internal combustion engine, a decompression bracket  2  is fixed on the valve rocker shaft bracket  1 , a decompression shaft  3  is located above the valve rocker  5  and is in movable fit with the decompression bracket  2 , a decompression cushion block  6 , springs  4  and a snap spring  7  are installed on the decompression shaft  3 , the decompression cushion block  6  is located between two springs  4 , the lengths and elastic forces of the two springs  4  are consistent, the snap spring  7  limits the positions of the springs  4 , an electromagnet  9  is fixed on a valve chamber cover, a movable iron core  8  is fixedly connected with the decompression shaft  3 , the operation of the electromagnet  9  is controlled by a time-delay relay  10 , and when the internal combustion engine is stopped, the decompression cushion block  6  is located between the decompression shaft  3  and the valve rocker  5 . 
     When the internal combustion engine needs to be stopped, the time-delay relay  10  controls the electromagnet  9 , the time-delay relay  10  switches on the circuit of the electromagnet  9 , the movable iron core  8  propels the decompression shaft  3  to move towards the direction of the valve rocker  5 , the springs  4  are compressed, when the valve rocker  5  drops, the decompression cushion block  6  is located between the valve rocker  5  and the decompression shaft  3 , the circuit of the electromagnet  9  is switched off, under the acting force of the valve spring  12 , the decompression cushion block  6  is located between the valve rocker  5  and the decompression shaft  3  and cannot be reset, the valve rod  11  cannot arrive at a valve closing position, and the valve is at an open state. When the internal combustion engine needs to be started, a signal is sent to the time-delay relay  10  at first, so that the position of the decompression cushion block  6  is maintained between the valve rocker  5  and the decompression shaft  3 , the power supply of a starter is turned on, the starter drives a flywheel to rotate, a crankshaft of the internal combustion engine reaches a starting speed, the time-delay relay  10  switches off the circuit of the electromagnet  9 , when the valve rocker  5  moves downwards, the decompression cushion block  6  is reset under the acting force of the springs  4 , the valve rod  11  arrives at the valve closing position, and the internal combustion engine is started. 
     In this invention, the valve rocker naturally drops by means of the operation of the internal combustion engine itself, when a certain space is generated with the decompression shaft, a cushion block is inserted in the space so that the valve rod cannot operate to the valve closing position, and the valve is at the open state. The device only needs a very small acting force for opening the valve, and most components can be placed in the valve chamber cover, so that no space is occupied, installation is simple and convenient, the structure is mechanical, the components are few, the reliability is high and the cost is low. 
     Embodiment 2 
     In  FIG. 2 , a valve rocker shaft bracket  1 , a valve rocker  5 , a valve rod  11  and a valve spring  12  are original parts of an internal combustion engine, a decompression bracket  2  is fixed on the valve rocker shaft bracket  1 , a decompression shaft  3  is located above the valve rocker and is in stationary fit with the decompression bracket  2 , a decompression cushion block  6  and springs  4  are installed on the decompression shaft  3 , the decompression cushion block  6  is located between two springs  4 , the lengths and elastic forces of the two springs are consistent, a shifting fork shaft  13  is located above the decompression shaft  3  and is in movable fit with the decompression bracket  2 , a shifting fork  14  is fixedly connected with the shifting fork shaft  13 , the shifting fork  14  limits the positions of the springs  4 , an electromagnet  9  is fixed on a valve chamber cover, a movable iron core  8  is fixedly connected with the shifting fork shaft  13 , the operation of the electromagnet  9  is controlled by a time-delay relay  10 , and when the internal combustion engine is stopped, the decompression cushion block  6  is located between the decompression shaft  3  and the valve rocker  5 . 
     When the internal combustion engine needs to be stopped, the time-delay relay  10  controls the electromagnet  9 , the time-delay relay  10  switches on the circuit of the electromagnet  9 , the movable iron core  8  propels the shifting fork shaft  13  to move towards the direction of the valve rocker  5 , the shifting fork  14  compresses the springs  4 , when the valve rocker  5  drops, the decompression cushion block  6  is located between the valve rocker  5  and the decompression shaft  3 , the circuit of the electromagnet  9  is switched off, under the acting force of the valve spring  12 , the decompression cushion block  6  is located between the decompression shaft  3  and the valve rocker  5  and cannot be reset, the valve rod  11  cannot arrive at a valve closing position, and the valve is at an open state. When the internal combustion engine needs to be started, a signal is sent to the time-delay relay  10  at first, so that the position of the decompression cushion block  6  is maintained between the valve rocker  5  and the decompression shaft  3 , the power supply of a starter is turned on, the starter drives a flywheel to rotate, a crankshaft of the internal combustion engine reaches a starting speed, the time-delay relay  10  switches off the circuit of the electromagnet  9 , when the valve rocker  5  moves downwards, the decompression cushion block  6  is reset under the acting force of the springs  4 , the valve rod  11  arrives at the valve closing position, and the internal combustion engine is started. 
     Embodiment 3 
     In  FIG. 3 , a decompression bracket  2  is fixed on a valve rocker shaft bracket  1 , an electromagnet  9  is fixed on the decompression bracket  2 , the action of the electromagnet  9  is controlled by a time-delay relay  10 , and when the internal combustion engine is stopped, a movable iron core  8  is located between the decompression bracket  2  and a valve rocker  5 . 
     The operating process in embodiment 3 is the same as the operating process of the structure in  FIG. 1  of the present invention. When the internal combustion engine needs to be stopped, the time-delay relay  10  controls the electromagnet  9 , the time-delay relay  10  switches on the circuit of the electromagnet  9 , the movable iron core  8  moves towards the direction of the valve rocker  5 , when the valve rocker  5  drops, the movable iron core  8  is inserted between the valve rocker  5  and the decompression bracket  2 , when the valve rocker  5  ascends, under the acting force of a valve spring  12 , the movable iron core  8  is clamped between the valve rocker  5  and the decompression bracket  2 , the circuit of the electromagnet  9  is switched off, the movable iron core  8  cannot be reset, a valve rod  11  cannot arrive at a valve closing position, and the valve is at an open state. When the internal combustion engine needs to be started, a signal is sent to the time-delay relay  10  at first, the circuit of the electromagnet  9  is switched on, so that the position of the movable iron core  8  between the valve rocker  5  and the decompression bracket  2  is not changed, the power supply of a starter is turned on, the starter drives a flywheel to rotate, the crankshaft of the internal combustion engine reaches a starting speed, the time-delay relay  10  switches off the circuit of the electromagnet  9 , when the valve rocker  5  drops, the movable iron core  8  is reset, the valve rod  11  arrives at the valve closing position, and the internal combustion engine is started. 
     Embodiment 4 
     In  FIG. 4 , a decompression bracket  2  is fixed on a valve rocker shaft bracket  1 , a hydraulic cylinder  15  is fixed on the decompression bracket  2 , the action of a piston  16  is controlled by corresponding high pressure oil and a return spring, and when the internal combustion engine is stopped, the piston  16  is located between the decompression bracket  2  and a valve rocker  5 . 
     The operating process in embodiment 4 is the same as the operating process in  FIG. 3  of the present invention. When the internal combustion engine needs to be stopped, a time-delay relay  10  controls the action of the hydraulic cylinder  15 , certain high pressure oil is supplied to the hydraulic cylinder  15  at first, the piston  16  moves towards the direction of the valve rocker  5 , when the valve rocker  5  drops, the piston  16  is inserted between the valve rocker  5  and the decompression bracket  2 , under the acting force of a valve spring  12 , the piston  16  is clamped between the valve rocker  5  and the decompression bracket  2 , the high pressure oil of the hydraulic cylinder  15  is discharged, the piston  16  cannot be reset, a valve rod  11  cannot arrive at a valve closing position, and the valve is at an open state. When the internal combustion engine needs to be started, certain high pressure oil is supplied to the hydraulic cylinder  15  at first, so that the position of the piston  16  between the valve rocker  5  and the decompression bracket  2  is not changed, the power supply of a starter is turned on, the starter drives a flywheel to rotate, a crankshaft of the internal combustion engine reaches a starting speed, the high pressure oil of the hydraulic cylinder  15  is discharged, when the valve rocker  5  drops, the piston  16  is reset, the valve rod  11  arrives at the valve closing position, and the internal combustion engine is started. 
     Embodiment 5 
     In  FIGS. 5 and 6 , a decompression bracket  2  is fixed on a valve rocker shaft bracket  1 , an electromagnet  9  is fixed on the decompression bracket  2 , the action of the electromagnet  9  is controlled by a time-delay relay  10 , a valve cap  17  is installed at the upper end of a valve rod  11 , and when the internal combustion engine is stopped, a movable iron core  8  is located between the decompression bracket  2  and the valve cap  17 . 
     The operating process in embodiment 5 is the same as the operating process of the structure in  FIG. 1  of the present invention. When the internal combustion engine needs to be stopped, the time-delay relay  10  controls the electromagnet  9 , the time-delay relay  10  switches on the circuit of the electromagnet  9 , the movable iron core  8  moves towards the direction of the valve cap  17 , when the valve cap  17  drops, the movable iron core  8  is inserted between the valve cap  17  and the decompression bracket  2 , when the valve cap  17  ascends, under the acting force of a valve spring  12 , the movable iron core  8  is clamped between the valve cap  17  and the decompression bracket  2 , the circuit of the electromagnet  9  is switched off, the movable iron core  8  cannot be reset, a valve rod  11  cannot arrive at a valve closing position, and the valve is at an open state. When the internal combustion engine needs to be started, a signal is sent to the time-delay relay  10  at first, the circuit of the electromagnet  9  is switched on, so that the position of the movable iron core  8  between the valve cap  17  and the decompression bracket  2  is not changed, the power supply of a starter is turned on, the starter drives a flywheel to rotate, a crankshaft of the internal combustion engine reaches a starting speed, the time-delay relay  10  switches off the circuit of the electromagnet  9 , when the valve cap  17  drops, the movable iron core  8  is reset, the valve rod  11  arrives at the valve closing position, and the internal combustion engine is started. 
     The operating processes in embodiment 3, embodiment 4 and embodiment 5 are the same as the operating process in  FIG. 1  of the present invention, the difference lies in that the opening of each valve is controlled by an electromagnet or a hydraulic oil cylinder, so that the acting force of opening the valve is smaller, and the entire device can be completely installed in the valve chamber cover, so that the external size and the structural form of the existing internal combustion engine are not changed at all, and the device is particularly easy to install on cars. 
     Embodiment 6 
     In  FIGS. 7 and 8 , a cylinder cover  101 , a valve tappet  11 , a rocker seat  106 , a rocker  5 , a rocker shaft  105  and a valve spring  12  are original parts of an internal combustion engine, a decompression fulcrum bar driving mechanism  110  and a supporting block  103  are fixed at the upper part of the cylinder cover  101  and at the lower part of the rocker  5  (as shown in  FIG. 8 ), a decompression fulcrum bar  104  is connected with the decompression fulcrum bar driving mechanism  110 , and the decompression fulcrum bar  104  is driven by the decompression fulcrum bar driving mechanism  110  to achieve the extension and retraction of the decompression fulcrum bar  104 . 
     When the internal combustion engine needs to be stopped, a time-delay relay  10  sends a signal to the decompression fulcrum bar driving mechanism  110  at first, the decompression fulcrum bar driving mechanism  110  drives the decompression fulcrum bar  104  to extend, when one end of the rocker  5  is jacked up by the valve tappet  11  to open a valve  109 , a space is generated between the rocker  5  and the supporting block  103 , one end of the decompression fulcrum bar  104  extends to the upper side of the supporting block  103  and is stopped, the decompression fulcrum bar  104  contacts the upper surface of the supporting block  103 , as shown in  FIG. 7 , when the rocker  5  drops, the decompression fulcrum bar  104  is located between the rocker  5  and the supporting block  103 , the rocker  5  is pressed on the decompression fulcrum bar  104 , as shown in  FIG. 7 , the decompression fulcrum bar  104  on the supporting block  103  blocks the rocker  5  from dropping so that the rocker  5  can not move downwards, the valve  109  cannot arrive at a closing position due to the blocking by the rocker  5 , under the acting force of a valve spring  12 , the decompression fulcrum bar  104  is clamped between the rocker  5  and the supporting block  103  and cannot be reset, and the valve  109  is at an open state. When the internal combustion engine needs to be started, a signal is sent to the decompression fulcrum bar driving mechanism  110  at first, so that the decompression fulcrum bar  104  is maintained at a position below the rocker  5  to block the rocker  5  from dropping and the valve  109  from closing, the power supply of a starter is turned on, the starter drives a flywheel to rotate, a crankshaft of the internal combustion engine reaches a starting speed, the decompression fulcrum bar driving mechanism  110  drives the decompression fulcrum bar  104  to be reset and retracted, the decompression fulcrum bar  104  does not block the rocker  5  from dropping any more, the valve  109  arrives at the closing position under the action of the valve spring  12 , and the internal combustion engine is started to run. 
     In this invention, the valve rocker and the valve tappet move up and down by means of the operation of the internal combustion engine itself, when the rocker is lifted up, a decompression fulcrum bar is inserted below the rocker, the decompression fulcrum bar is supported by the supporting block, so that the valve corresponding to the rocker cannot operate to the valve closing position, and the valve is at the open state. The device only needs a very small acting force for opening the valve, and most components can be placed in the valve chamber cover, so that the height of the valve chamber cover is not increased, no space is occupied, installation and design of passenger cars are facilitated, installation is simple and convenient, the structure is mechanical, the components are few, the reliability is high and the cost is low.