Patent Application
20130199492
This disclosure is generally related to combustion engines.
The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Modern combustion engines generally include spark-ignition engines and compression-ignition engines. During operation, the efficiency of a combustion engine depends on many factors, including volumetric and thermodynamic efficiency.
It is known to employ engines with forced induction devices including turbo-chargers and super-chargers, which are predominantly add-ons to a basic engine design. While relatively easy to service, these devices can be problematic and are limited from several aspects inherent to their design.
An internal combustion engine includes a compressor cylinder having a respective inlet, a first outlet and a respective piston slideably movable within the compressor cylinder and operatively connected to a rotating crankshaft. The compressor cylinder provides a first stage of compression to a charge when the charge is transferred from the compressor cylinder during every revolution of the crankshaft. A first power cylinder includes a respective inlet in fluid communication with the first outlet of the compressor cylinder, a respective outlet and a respective piston slideably movable within the first power cylinder and operatively connected to the rotating crankshaft. The first power cylinder provides a second stage of compression and firing of the charge within the first power cylinder every two revolutions of the crankshaft.
One or more embodiments will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring now to the drawings, wherein the showings are for the purpose of illustrating certain exemplary embodiments only and not for the purpose of limiting the same,
The compressor cylinder 2 may include a bore fitted with a respective reciprocating piston 13 (shown in
In an exemplary embodiment, the compressor cylinder 2 is a two-stroke compressor cylinder where one intake stroke (first stroke) and one compression stroke (second stroke) occurs during every revolution of the crankshaft. In other words, after the charge is received within the compressor cylinder 2 during the first stroke, the charge within the compressor cylinder is transferred to alternating ones of the first and second power cylinders 14,16, respectively, during a second stroke of the piston 13 respective to the compressor cylinder 2 every crankshaft revolution. Accordingly, the compressor cylinder 2 can include a respective valve located at the compressor cylinder inlet 4 and selectively activated between an open position for receiving the charge during the first stroke and a closed position for transferring the charge during the second stroke. The transferring provides a first compression (first stage of compression) to the charge. The first compression to the charge is realized through the compressor cylinder 2 having a larger volume than each of the first and second power cylinders 14,16, respectively. The first stroke of the piston 13 respective to the compressor cylinder includes movement in a direction towards bottom dead center of the compressor cylinder 2. Likewise, the second stroke of the piston 13 respective to the compressor cylinder includes movement in a direction toward top dead center of the compressor cylinder 2.
The first power cylinder 14 includes an inlet 10 (first power cylinder inlet) in fluid communication with the compressor cylinder first outlet 6, an outlet 18 (first power cylinder outlet) and a respective piston 15 (shown in
In an exemplary embodiment of the present disclosure, the pistons 15, 17 respective to each of the first and second power cylinders 14,16, respectively, move in a direction opposite to the direction of movement of the piston 13 respective to the compressor cylinder 2. Thus, the pistons of the power cylinders move in phase opposition to the piston of the compressor cylinder. Such phase opposition movement may be absolute thus encompassing the entire rotation of the crankshaft or may be offset by some predetermined angle wherein top dead and bottom dead center crankshaft angle position of the piston of compressor cylinder may be advanced or retarded with respect to the top dead and bottom dead center crankshaft angle position of the pistons of the power cylinders. Such offsets can, for example, provide varying degrees of effective compression ratios of the charge and account for intake flow dynamics and various intake runner geometries. Generally, however, it is envisioned that movement of the piston of compressor cylinder is substantially in phase opposition to the movement of the pistons of the power cylinders. As used herein, substantially in phase opposition includes such offset angles. Preferably, such an offset angle is less than about +/−90 degrees of crankshaft rotation. More preferably, such an offset angle is less than about +/−45 degrees of crankshaft rotation. More preferably, such an offset angle is less than about +/−22.5 degrees of crankshaft rotation.
A first port 9 is disposed between the compressor cylinder first outlet 6 and the first power cylinder inlet 10. Each of the compressor cylinder first outlet 6 and the first power cylinder inlet 10 having valves selectively activated between open and closed positions providing valve timing sufficient for selectively providing fluid communication between the compressor cylinder 2 and the first power cylinder 14 via the first port 9. Similarly, a second port 11 is disposed between the compressor cylinder second outlet 8 and the second power cylinder inlet 12. Each of the compressor cylinder second outlet 8 and the second power cylinder inlet 12 having valves selectively activated between open and closed positions providing valve timing sufficient for selectively providing fluid communication between the compressor cylinder 2 and the second power cylinder 16 via the second port 11.
As aforementioned, each of the valves variously corresponding to respective ones of the inlets and outlets of the compressor cylinder 2 and the first and second power cylinders 14,16, respectively, can be selectively activated between open and closed positions providing valve timing sufficient to enable two-stroke operation of the compressor cylinder 2 and four-stroke operation in each of the power cylinders 14,16, respectively. The two-stroke operation of the compressor cylinder 2 includes receiving the charge within the compressor cylinder 2 during the first stroke of the piston respective to the compressor cylinder 2 and transferring the charge within the compressor cylinder 2 to alternating ones of the first and second power cylinders 14,16, respectively, during the second stroke of the piston 13 respective to the compressor cylinder 2 providing the first stage of compression to the charge every crankshaft revolution. The four-stroke operation in each of the first and second power cylinders 14,16, respectively, provides the second stage of compression to the charge within alternating ones of the first and second power cylinders 14,16, respectively, every two crankshaft revolutions.
Referring to
In an exemplary embodiment, the first and second long route EGR ports 352,252, respectively, can be fluidly coupled to respective ones of first and second long route EGR heat exchangers 196,116, respectively, disposed upstream of respective first and second long route outlet valves 152,154, respectively. In one embodiment, at least one first and/or second long route EGR heat exchanger 196 and/or 116, respectively, can be utilized to cool the recirculated external EGR entering the inlet 400 of the compressor cylinder 200 during high load operation. In another embodiment, at least one first and/or second long route EGR heat exchanger 196 and/or 116, respectively, can be utilized to heat the recirculated external EGR entering the inlet 400 of the compressor cylinder 200 during low load operation. In an alternative embodiment, at least one first and/or second long route EGR heat exchanger bypass port 151 and/or 153, respectively, can be utilized to bypass at least one respective first and/or second long route EGR heat exchanger 196 and/or 116, respectively, when the long route EGR heat exchangers 196,116 are utilized to cool the recirculated EGR. For instance, the long route EGR heat exchanger bypass ports 151,153 by pass the respective long route EGR heat exchangers 196,116 so that the recirculated EGR is not cooled during operation at low load, and hence, provide heat to the charge entering the inlet 400 of the compressor cylinder 200.
In an exemplary embodiment of the present disclosure, the engine 101 can further include at least one first and second compressed charge heat exchanger 195 and/or 115, respectively, disposed between the compressor cylinder 200 and at least one of the first and second power cylinders 140 and/or 160, respectively. Specifically, a first port 190 providing fluid communication between the compressor cylinder 200 and the first power cylinder 140 when a first compressor outlet 204 and the first power cylinder inlet 142 are selectively in open positions, can be coupled to the first compressed charge heat exchanger 195. Likewise, a second port 110, providing fluid communication between the compressor cylinder 200 and the second power cylinder 160 when a second compressor outlet 206 and the second power cylinder inlet 162 are selectively in open positions, can be coupled to the second compressed charge heat exchanger 115. The compressed charge heat exchangers 195,115 can provide at least one of heating and cooling to the transferred charge within respective ones of the first and second ports 190,110 subsequent to a first compression and preceding a second compression to the charge. In one embodiment, the compressed charge heat exchangers 195,115 can be utilized to provide heating to the transferred charge during low load operation within respective power cylinders 140,160, respectively. In another embodiment, the heat exchanger can be utilized to provide cooling to the transferred charge during high load operation. For instance, the compressed charge heat exchanger can provide cooling to prevent autoignition when the power cylinders are operating in at least one of spark-ignition, spark-assisted homogenous charge compression ignition (HCCI) and spark-assisted premixed charge compression ignition (PCCI) modes. The cooling of the transferred charge can be utilized to increase the density of the transferred charge into at least one of the first and second power cylinders 140,160, respectively. In an alternative embodiment, each port 190,110 can include a compressed charge heat exchanger bypass port 191,111, respectively. The first and second compressed charge heat exchanger bypass ports 191,111, respectively, bypass the respective compressed charge heat exchangers 195,115, respectively, when the compressed charge heat exchangers 195,115 are utilized to cool the transferred charge. For instance, the compressed charge heat exchanger bypass ports 191,111 bypass the respective compressed charge heat exchangers 195,115, respectively, so that the transferred charge is not cooled during operation at low load in each of the respective power cylinders 140,160.
In an exemplary embodiment of the present disclosure, first and second short route EGR ports 351,251, respectively, can be fluidly coupled to respective ones of first and second short route EGR heat exchangers 197,117, respectively, disposed upstream of respective first and second short route outlet valves 355,255, respectively. In one embodiment, at least one first and/or second short route EGR heat exchanger 197 and/or 117, respectively, can be utilized to cool the recirculated external EGR entering respective ones of the first and second power cylinders 140,160, respectively, during high load operation. In another embodiment, at least one first and/or second short route EGR heat exchanger 197,117, respectively, can be utilized to heat the recirculated external EGR entering respective ones of the first and second power cylinders 140,160, respectively, during low load operation. In an alternative embodiment, at least one first and/or second short route EGR heat exchanger bypass port 123 and/or 121, respectively, can be utilized to bypass at least one respective first and/or second short route EGR heat exchanger 197 and/or 117, respectively, when the short route EGR heat exchangers 197,117 are utilized to cool the recirculated EGR. For instance, the short route EGR heat exchanger bypass ports 123,121 bypass the respective short route EGR heat exchangers 197,117 so that the recirculated EGR is not cooled during operation at low load, and hence, provide heat to the charge entering the power cylinders 140,160. In an alternative embodiment, the compressed charge heat exchangers 195,115 can utilize the heat from the external EGR recirculated via respective short route EGR ports 351,251.
During the first compression (first stage of compression) illustrated in
During the second compression of the charge shown in
During the power (expansion) stroke shown in
During the exhaust stroke shown in
It is understood that while
A control module can be utilized to control the operation of the pistons and selective closing and opening of the valves through 2-stroke operation of the compressor cylinder 2 and 4-stroke operation in each of the first and second power cylinders 14,16, respectively.
Control module, module, control, controller, control unit, processor and similar terms mean any one or various combinations of one or more of Application Specific Integrated Circuit(s) (ASIC), electronic circuit(s), central processing unit(s) (preferably microprocessor(s)) and associated memory and storage (read only, programmable read only, random access, hard drive, etc.) executing one or more software or firmware programs or routines, combinational logic circuit(s), input/output circuit(s) and devices, appropriate signal conditioning and buffer circuitry, and other components to provide the described functionality. Software, firmware, programs, instructions, routines, code, algorithms and similar terms mean any controller executable instruction sets including calibrations and look-up tables. The control module has a set of control routines executed to provide the desired functions. Routines are executed, such as by a central processing unit, and are operable to monitor inputs from sensing devices and other networked control modules, and execute control and diagnostic routines to control operation of actuators. Routines may be executed at regular intervals, for example each 3.125, 6.25, 12.5, 25 and 100 milliseconds during ongoing engine and vehicle operation. Alternatively, routines may be executed in response to occurrence of an event.
The disclosure has described certain preferred embodiments and modifications thereto. Further modifications and alterations may occur to others upon reading and understanding the specification. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.
