MXPA99000891A - Four-stroke engine with two-tieme compression release brake - Google Patents

Abstract

The present invention relates to an internal combustion engine, comprising: a intake valve associated with a cylinder of the engine, an exhaust valve associated with the cylinder, a intake cam having at least one lobe synchronized with possible openings of the intake valve, an exhaust cam having at least one synchronizing lobe with possible openings of the exhaust valve, a first hydraulic link containing hydraulic fluid operatively coupled between the intake cam and the intake valve for selectively respond to at least one lobe of the intake cam by causing the intake valve to open, a second hydraulic link containing hydraulic fluid operatively coupled between the exhaust cam and the exhaust valve to respond selectively to the at least one lobe of the exhaust cam by causing the exhaust valve to open, a first hydraulic fluid control to control in a manner It detects the pressure of the hydraulic fluid in the first hydraulic link to selectively modify the intake valve openings in response to the at least one lobe of the intake cam, wherein the first hydraulic fluid control is selectively operable to allow that the intake valve opens in a first engine operating condition and remains closed during a possible opening in a second engine operating condition in response to at least one lobe of the intake cam, and a second fluid control Hydraulically to selectively control the hydraulic fluid pressure in the second hydraulic link to selectively modify the exhaust valve openings in response to at least one lobe of the escape cam.

Description

FOUR-STROKE ENGINE WITH TWO-STEM COPRESSION RELEASE BRAKE BACKGROUND OF THE INVENTION This invention relates to variable timing valve activation systems, and more particularly to an apparatus for controlling, adjusting or modifying the intake and exhaust valve timing or other related characteristics, hydraulically linked timing of exhaust systems and intake with high-speed electromagnetic valves to achieve compression delay effects during each revolution of the crankshaft. The commonly assigned and co-pending US Patent Application Serial No. 08/512, 528 filed on August 8, 1995 shows how motion lost in the hydraulic links between the engine cylinder valves can be selectively employed. and the mechanical inputs that normally control these valves to modify the openings of the valves in relation to the normal inputs. These modifications can be timing or number of valve openings, or the engine operation mode can be changed from positive energy to compression release brake. However, if the engine is a four-stroke engine in a positive energy mode, it will also have four times in compression-release engine braking mode. This means that it is only possible for each engine cylinder to produce a compression release event during every two revolutions of the engine crankshaft. Sickier US Pat. No. 4,572,114 shows an apparatus for converting a four-stroke engine to two-stroke operation during braking of the compression release engine. This allows each engine cylinder to produce a compression release event during each revolution of the engine crankshaft, approximately doubling the available compression release braking compared to four-stroke braking. However, the Sickier apparatus is relatively complicated, employing, for example, two hydraulic connections (e.g., 136 and 212 in Figure 5 or 258 and 212 in Figure 7) to each valve opening mechanism. In view of the foregoing, it is an object of the invention to extend the operating principles of the above-mentioned application concurrently presented to facilitate the selective operation of a four-stroke engine in two-stroke compression release braking mode. BRIEF DESCRIPTION OF THE INVENTION These and other objects of the invention are achieved in accordance with the principles of the invention using hydraulic links with selective lost motion between the intake cams and the intake valves and between the exhaust cams and the exhaust valves. of an internal combustion engine. Sufficient lobes in the cams can be provided to produce openings of four-stroke positive energy mode of the valves and braking mode operation of the two-cycle engine compression release engine, with the hydraulic links of motion lost operating to select either the lobes of four times or the lobes of two times. The hydraulic links for the intake or exhaust valves can be selectively hydraulically interconnected to allow the lobes on one type of cam to produce openings of the other type of valve when two-stroke operation is desired. This may allow the profiles of the individual cams to be simplified in some way. The hydraulic links and the possible interconnections of these links are preferably controlled electronically (for example, by means of a suitable programmable microprocessor). This control can respond not only to the desired mode of engine operation, but also to various vehicle or engine operating conditions so that timings and / or extension of various valve openings can be adjusted and thus optimized for current operating conditions in the current engine operating mode. Additional aspects of the invention, its nature and several advantages will be evident from the accompanying drawings and the following description details the preferred modalities. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified schematic diagram of a portion representative of an illustrative embodiment of an internal combustion engine constructed in accordance with this invention. Figure 2a is a simplified diagram of the lobes on the take-up cam in the apparatus of Figure 1. Figure 2b is a simplified diagram of the lobes on the exhaust cam in the apparatus of Figure 1. Figure 2c, is a simplified diagram of motor cylinder valve openings in the apparatus of Figure 1 during operation of the braking mode of the two-stroke compression release motor. Figure 2d is a simplified diagram of motor cylinder valve openings in the apparatus of Figure 1 during the operation of the four-stroke positive energy mode. Figure 2e is a simplified diagram of traces of illustrative signs in the apparatus of Figure 1 to control that the apparatus produces an operation as shown in Figure 2c. Figure 2f is a simplified diagram of traces of illustrative signs in the apparatus of Figure 1 to control that the apparatus produces an operation as shown in Figure 2d. Figure 3 is a view similar to Figure 1, but shows an alternative embodiment of the invention. Figures 4a to 4f are similarly similar figures to Figures 2a to 2f, but for the alternative embodiment shown in Figure 3. Figure 5 is another view similar to Figure 1, but shows another alternative embodiment of the invention.

Figures 6a to 6f are similarly similar figures to Figures 2a to 2f, but for the alternative embodiment shown in Figure 5. Figure 7 is another view similar to Figure 1, but shows another alternative embodiment of the invention. Figures 8a to 8f are similarly similar figures to Figures 2a to 2f, but for the alternative embodiment shown in Figure 7. Figure 9a is an illustrative diagram of an engine cam profile that is useful for explaining certain operating principles of the invention. Figure 9b is a diagram showing several alternative hydraulic valve control signals synchronized with the motor cam profile of Figure 9a, in accordance with this invention. Figure 9c, is a diagram showing several alternative motor valve openings in response to the motor cam profile of Figure 9a, and the hydraulic valve control signals in Figure 9b. Figure 10 is another view similar to Figure 1, but shows another alternative embodiment of the invention. Figures 11a to 11f are respectively similar to Figures 2a to 2f, but for the alternative embodiment shown in Figure 10. Figure 12 is another view similar to Figure 1, but shows another alternative embodiment of the invention.

Figures 13a to 13f, are respectively similar to Figures 2a to 2f, but for the alternative embodiment shown in Figure 10. Detailed Description of the Preferred Modes As shown in Figure 1, an internal combustion engine 10 illustrative constructed of according to this invention has a motor cylinder head 20, with intake and exhaust valves 30 and 60, mounted for vertical alternation therein. Both of the valves shown 30 and 60 serve a representative cylinder in the engine 10. The intake valve 30 is elastically biased upwards to the closed position shown by pre-pressurized compression coil springs 32. The exhaust valve 60 is also bypassed elastically upwards towards the closed position shown by previously pressed compression coil springs 62. The valve 30 can be pushed down to isolate it by downward movement of the secondary piston 58. The valve 60 can be pushed down to open it by movement downstream of the secondary piston 68. The intake valve 30, has an associated rotary motor cam 40, and the exhaust valve 60 also has an associated rotary motor cam 70. The intake and exhaust cams 40 and 70 rotate in synchronization with the engine crankshaft. The cams 40 and 70 have lobes 42 and 72 to produce openings of the valves 30 and 60, as will be described in detail below. Each of the cams 40 and 70 is operatively linked to the associated valve 30 and 60 by hydraulic circuits. The pump 90 supplies pressurized hydraulic fluid to this circuit from the manifold 92. The hydraulic fluid may be engine lubricating oil, motor fuel, or any other suitable fluid. The outlet pressure of the pump 90 is relatively low (e.g., 50 to 100 psi). This pressure is sufficient to fill the hydraulic circuit with fluid via the check valves 94, 96 and 98, and to push the master pistons 50 and 80 and the secondary pistons 58 and 88 outwardly in contact with the cams 40 and 70 and the pistons 40 and 70. upper parts of the valves 30 and 60. However, the outlet pressure of the pump 90 is not high enough to cause the secondary pistons 58 and 88 to open the valves 30 and 60. When an intake cam lobe 42 passes the Master 50 piston, that cam lobe presses the master piston inward. If the electronically controlled hydraulic fluid valve 52 is open when this occurs, the hydraulic fluid displaced by the master piston 50 escapes from the hydraulic subcircuit 54 via the valve 52 and accumulates in the hydraulic fluid accumulator 22. The accumulator 22 maintains an amount of hydraulic fluid at approximately the outlet pressure of the pump 90 to immediately refill the rest of the hydraulic circuits during the return stroke of the master pistons 50 and 80, which are not concurrent with the return strokes of the secondary pistons 58 and 88. If the accumulator 22 receives too much hydraulic fluid, its plunger moves downwardly enough to open a drain of hydraulic fluid 24 back to the manifold 92. If , instead of opening as described above, the valve 52 closes when a cam lobe 42 passes over the master piston 50, the hydraulic fluid is trapped in the subcircuit 54. Consequently, the pressure in this subcircuit increases significantly, and the hydraulic fluid displaced by the master piston 50 causes a corresponding hydraulic displacement of the secondary piston 58. The resulting downward movement of the secondary piston opens the intake valve 30. When the aforementioned lobe 42 has passed the master piston 50, the elements 50, 58 and 30 return to their original positions. The lobes 72 in the exhaust cam 70, cooperate with the valve 82 (similar to the valve 52) to selectively produce the openings of the exhaust valve 60 in a manner similar to that described above for the elements 40, 50, 52, 54, 58 and 30. Thus, if the valve 82 is open when an exhaust cam lobe 72 for the master piston 80, the hydraulic fluid displaced by the master piston escapes from the hydraulic subcircuit 84 to the accumulator 22, via the valve 82. This prevents the secondary piston 88 from opening the exhaust valve 60. But if the valve 82 is closed when an exhaust cam lobe 72 passes the master piston 80, the pressure of the hydraulic fluid trapped in the subcircuit 84 is substantially increased. . This causes the secondary piston 88 to move downward and open the valve 60. When the aforementioned lobe 72 has passed the master piston 80, the elements 80, 88 and 60 return to their original positions. The opening and closing of valves 52 and 82 (and other similar valves associated with the engine) is controlled by the electronic control circuit 100. Control circuit 100, which may include a suitably programmed microprocessor, receives inputs from the sensors of vehicle and / or engine 102. These inputs allow the control circuit 100 to maintain basic synchronization with the engine. They also allow the vehicle activator to select the engine operating mode (eg, positive operation mode or compression release engine braking mode). These inputs can provide information about various parameters of vehicle operation and / or variable motor such as the speed of vehicle and / or engine. The control circuit 100 responds to its inputs by selecting the openings and closures of the valves 52 and 82 that are appropriate to cause the valves 30 and 60 to open and close as required for the desired engine operation mode. The control circuit 100 can also respond to these inputs by adjusting the timing and duration of the openings and closures of the valves 52 and 82 so that the openings and closures of the valves 30 and 60 are modified (for example, with respect to the timing, duration and / or height) to optimize engine performance for current vehicle and / or engine operating conditions. The examples of the above principles will now be discussed with respect to Figures 2a to 2f. Figure 2a shows the profile of the intake cam 40 drawn against the angle of the crankshaft of the engine. (The same crankshaft angle scale shown in Figure 2a applies to the entire group in Figure 2. The upper dead center of the compression stroke of the associated engine cylinder in the four-stroke positive operating mode is in 0o and again at 720 °). Figure 2b shows the profile of the exhaust cam 70. Figure 2c shows the openings of the valves 30 and 60 that occur during the braking mode of the two-stroke compression release engine. (In Figure 2c, and other similar figures, each valve opening 30 is identified with the reference number 30, and each valve opening 60 is identified with the reference number 60. The letters "a" or "b" are used in Figure 2c and in similar figures for indicate if the opening of the valve is due to the "a" or "b" lobe in the associated cam 40/70). Figure 2c shows that the intake valve 30 is opened during each downward stroke of the associated engine piston to admit air into the associated engine cylinder. Figure 2c further shows that the exhaust valve 60 opens near the end of each upward stroke of the associated engine piston to produce a release of compressed air to the engine exhaust handle. Therefore, a compression release event occurs during each 360 degrees of rotation of the engine crankshaft, thus producing two-stroke compression release motor braking. With release events occurring in this manner twice as often as in the case of four-stroke engine braking, approximately twice the vehicle and engine retard power is available compared to the engine release braking system. four-stroke compression Figure 2d shows the openings of the valves 30 and 60 that occur during the four-stroke positive energy operation mode of the engine. Figure 2e shows the traces of signals produced by the control circuit 100 for controlling valves 52 (lower signal trail t52) and 82 (upper signal trail t82) during operation of engine compression release engine braking mode . In these (and other traces of similar signals) the valve 52 or 82 is closed when the associated signal trail is low, and the valve is open when the signal trail is high. In Figure 2e, the signal to control the valve 52 is low all the time. Therefore, the valve 52 is closed all the time during compression release motor braking, and the intake valve 30 opens in response to the lobes of the intake cam 42a and 42b. On the other hand, the signal for controlling the valve 82 is high during the initial portion of the exhaust cam lobe 72a and low during a drag portion of that cam lobe (including an additional prominence 72a ') and all the time. Therefore, the valve 82 is open during the initial portion of the cam lobe 72a but closed during the additional prominence 72a 'and during the lobe 72b. Accordingly, the exhaust valve 60 remains closed during the initial portion of the lobe 72a 'and during the lobe 72b. Accordingly, the exhaust valve 60 remains closed during the initial portion of the lobe 72a but opens (as in 60a in Figure 2c) in response to the additional prominence 72a '. The exhaust valve 60 also opens (as in 60b in Figure 2c) in response to the lobe 72b. Figure 2f shows the traces of signals produced by the control circuit 100 to control the valves 52 (lower signal trail t52) and 82 (upper signal traces t82) during operation of the positive operation mode of the engine. The signal for controlling the valve 52 is high during the intake cam lobe 42a but low during the intake cam lobe 42b. therefore, the valve 52 is open during the lobe 42a but closed during the lobe 42b. This allows the intake valve 30 to completely ignore the lobe 42a remaining closed during that lobe. However, the valve 30 is opened (as in 30b in Figure 2d) in response to the lobe 42b. The signal for controlling the valve 82 in Figure 2f is high during the exhaust cam lobe 72b and the rear portion of the exhaust cam lobe 72a. At other times this signal is low. Therefore, the valve 82 is open during the lobe 72b and the posterior portion of the lobe 72a, but closed during the initial portion of the lobe 72a. This allows the exhaust valve 60 to remain closed during the lobe 72b, completely ignoring that lobe. The exhaust valve 60 is opened (as in 60a in Figure 2d) in response to the initial portion of the lobe 72a, but ignores the dragging protrusion 72a 'in that lobe and closed approximately by the crankshaft angle of 360 °. In addition to opening and closing the valves 52 and 82 as described above with respect to Figure 2 to select which cam lobe motor cylinder valves 30 and 60 to respond to, the control circuit 100 can make more subtle modifications in the timing of the operation of the valves 52 and 82 to produce more subtle changes in the openings and closures of the valves 30 and 60. For example, the start of a compression release event such as 60a or 60b in Figure 2c can be delay in relation to the start of the associated function of the cam by delaying the closing of the valve 82 a bit in relation to the beginning of that function of the cam. Similarly, a valve 30 or 60 can be closed before opening the associated valve 52 or 82 before the end of the function of the cam that produced that opening of the motor valve. The distance that a valve 30 or 60 opens can also be reduced selectively by opening, for example, the associated valve 52 or 82 briefly before or when the peak of a cam function is reached. It may be desirable to make these types of changes in the operation of the engine valve to optimize the engine for various vehicle and / or engine operating conditions (e.g., changes in vehicle speed and / or engine speed). For example, such changes can optimize the amount of engine braking produced for various engine speeds or, in positive operating mode, can optimize the fuel consumption and / or engine emissions for various engine speeds. The control circuit 100 may be programmed to perform various algorithms or look-up table operations to determine the precise valve timing of the motor that is most appropriate for the current values of the inputs 102 it is receiving. Then the control circuit 100 produces the signals applied to the valves 52 and 82 that are required to produce those motor valve timing. The different types of subtler modification of the operation of the engine valve in relation to the motor cam functions that have been described are described in greater detail and are illustrated in the U.S. Patent Application of North America. Serial Number 08/512, 528, which is incorporated by reference herein. From the foregoing it will be appreciated that the apparatus of this invention provides a simple and effective way to operate an internal combustion engine in either a four-stroke positive energy mode or a two-stroke compression release engine braking mode, as well as how to make more subtle modifications of the timing of the valve in relation to the functions of the cam. FIG. 3 shows an alternative embodiment of the invention in which part of a take-up cam lobe is used during braking of the compression release motor to produce a compression release relief valve opening. The apparatus 10a shown in Figure 3 has many similarities to the apparatus of Figure 1 and the same reference numbers are used for the basically similar elements in both Figures, in addition to the electronically controlled hydraulic fluid valves 52 and 82, the apparatus shown in Figure 3 has another electronically controlled hydraulic fluid valve or separator 110 that can be switched to hydraulically connect either its ports A and B or its ports A and C. Port C is connected to hydraulic subcircuit 84 via conduit 112. Like the valves 52 and 82, the valve 110 is controlled by the electronic control circuit 100. Now the operation of the apparatus shown in Figure 3 will be explained., with reference to Figures 4a to 4f (respectively similar to Figures 2a to 2f). Figure 4a shows the profile of the take-up cam 40 in Figure 3. It should be noted that, as is usually the case in conventional engines, the take-up lobe 42b begins a little before the top dead center of the run of exhaust (that is, a little before the crankshaft angle of 360 °). Figure 4b shows the profile of the escape cam 70 in Figure 3. It should be noted that the exhaust cam lobe 72a in Figure 4 does not require the additional dragging protrusion 72a ', shown in Figure 2b.

Figure 4c shows the openings of the intake and exhaust valves 30 and 60 during the two-stroke compression release engine braking operation of the engine 10a. This pattern is very similar to the pattern shown in Figure 2c, except that the opening of the exhaust valve 60x (which takes the place of the opening of the exhaust valve 60a in Figure 2c) is produced by an initial portion. of the intake cam lobe 42b as will be described in more detail with reference to Figure 4e. Figure 4d shows the openings of the intake and exhaust valves 30 and 60 during the four-stroke positive energy mode operation of the engine 10a. Figure 4e shows the traces of signals produced by the control circuit 100 during the operation of the two-stroke compression release motor braking mode of the motor 10a to control the valve 52 (lower signal trail t52) the valve 82 ( medium signal trail t82) and valve 110 (upper signal trace 1110). As in Figure 2e, each of the lower signal traces in Figure 4e is low when the associated valve 52 or 82 is closed, and high when the associated valve is open. The upper signal trail in Figure 4e is low when the valve 110 hydraulically connects its ports A and B, and high when the valve 110 hydraulically connects its ports A and C. The lower signal trail is under all the time in Figure 4e. The average signal trail is low, except during the initial portion of the exhaust cam lobe 72a. The upper signal trail causes the valve 110 to connect its ports A and B for all times except for an initial portion of the intake cam lobe 42b. Figure 4f shows the traces of signals produced by the control circuit 100 during the four-stroke positive energy mode operation of the motor 10a. Again, the lower signal t52 in Figure 4f controls the valve 52, the medium signal t82 controls the valve 82, and the upper signal t110 controls the valve 110. The lower signal trace is high during the intake cam lobe 42a , which causes the intake valve 30 to completely ignore the intake cam lobe 42a. However, this signal is low during the lobe 42b so that the tap valve 30 opens in response to that lobe as shown at 30b in Figure 4d. The average signal trail in Figure 4f is low except during the exhaust cam lobe 72b. This causes the exhaust valve 60 to open (as shown at 60a in Figure 4d) in response to the exhaust cam lobe 72a, but to remain closed during the lobe 72b. The upper signal trace in Figure 4f is low at all times so that the valve 110 connects its ports A and B at all times. As a result of the signals shown in Figure 4e, the tap valve 30 is opened (it is at 30a in Figure 4c) in response to the tapped lobe 42b. Also as a result of the signals shown in Figure 4d, the exhaust valve 60 is opened (it is at 60b in Figure 4c) in response to the exhaust cam lobe 72b. The exhaust valve 60 does not open during the exhaust cam lobe 72a because the valve 82 is the direct stroke of the master piston 80 in response to that cam lobe. However, towards the end of the lobe 72a, the valve 82 closes and the valve 110 is changed to its position of the port A-C. This allows the high pressure hydraulic fluid driven by the master piston 50 at the start of the intake cam lobe 42b to flow to the secondary piston 88, thereby opening the exhaust valve 60 as shown at 60x in Figure 4c. As soon as an opening of the appropriate exhaust valve 60x is produced, the valve 110 returns to its position of port A-B. This allows the exhaust valve 60 to close and causes the remainder of the direct stroke of the master piston 50 to produce the opening of the intake valve 30., which is shown at 30b in Figure 4c. From the foregoing it will be seen that the apparatus of Figure 3 provides an alternative way of operating a motor in either a four-stroke positive energy mode or a two-stroke compression release motor braking mode. In addition, any of the more subtle types described above of engine valve response modifications to cam functions can also be implemented in the apparatus shown in Figure 3. Figure 5 shows another alternative embodiment of the invention in which part of an exhaust cam lobe is used during compression release motor braking to produce an extra intake valve opening. Again, the apparatus 10b shown in Figure 5 has many similarities with the apparatus of Figure 1. and the same reference numbers are used for similar elements in both Figures. The apparatus 10b has an additional electronically controlled hydraulic fluid valve or separator 120 that can be switched to hydraulically connect either its ports A and B or its ports A and C. The port C is connected to the hydraulic subcircuit 54 via the conduit 122. As the valve 120 is controlled by the electronic control circuit 100. The operation of the apparatus 10b will be explained with reference to Figures 6a to 6f, which are respectively similar to Figures 2a to 2f or Figures 4a to 4f. Figures 5 and 6a show that the take-up cam 40 has a single lobe 42. Figures 5 and 6b show that the exhaust cam 70 has two lobes 72a and 72b. Figure 6c shows that during braking of the two-stroke compression release motor, the exhaust valve 60 opens at 60b in response to the exhaust cam lobe 72b. The exhaust valve 60 also opens at 60a in response to an additional drive protrusion 72a 'in the lobe 72a. The intake valve 30 opens at 30x in response to an initial portion of the exhaust cam lobe 72a and at 30b in response to the intake cam lobe 42. Figure 6d shows that during the four-stroke positive energy mode, the exhaust valve 60 opens at 60a in response to the initial portion of the exhaust cam lobe 72a. The tap valve 30 opens at 30b in response to the intake cam lobe 42.

In Figures 6e and 6f, the upper signal trace t120 controls the valve 120. This trace is low for the connection of the valve port A to the valve port B. This trace is high for the connection of the valve port A to valve port C (In Figure 6f this trace is low at all times). The lower trace t52 in Figures 6e and 6f controls the valve 52 (high for open, low for closed). This trace is low at all times in both Figures 6e and 6f, but the valve 52 could be momentarily open to make the more subtle adjustments of the intake valve response as described above in relation to the other embodiments. The middle trail t82 in Figures 6e and 6f controls the valve 82 (high for open, low for closed). As shown by the upper trace t120 in Figure 6e, the valve 120 is switched to connect port A to port C during an initial portion of the exhaust cam lobe 72a. This causes the initial portion of the direct stroke of the master piston 80 in response to that lobe to open the intake valve 30 as shown at 30x in Figure 6c. After a suitable opening 30x has been produced, the valve 82 opens to suppress the intermediate portion of the lobe 72a and allow the valve 30 to close again. Then, the valve 120 is returned to the condition in which it connects port A to port B. Valve 82 closes again when the additional prominence 72a 'is about to begin. Accordingly, the additional prominence 72a 'causes the exhaust valve 60 to open as shown at 60a in Figure 6c.

In Figure 6f, the middle signal trail t82 shows that the valve 82 is open during the exhaust cam lobe 60b and the additional prominence 72a 'in the lobe 72a. This allows the exhaust valve 60 to ignore these functions of the exhaust cam during operation of the positive operating mode of the engine 10b. Again, the more subtle timing modifications described above in relation to the other embodiments may also be employed in the embodiment shown in Figure 5. Figures 6e and 6f show valve 52 that remains closed at all times during both modes of operation of the motor 10b. Therefore, the valve 52 and the path of the hydraulic circuit through that valve can be removed from the engine 10b if desired. On the other hand, it may be desired to retain the valve 52 to make some of the more subtle timing modifications mentioned in the previous paragraph. Another embodiment is shown in Figure 7. Elements that are similar in the above-described embodiments are identified again by the same reference numbers. Figures 8a to 8f refer to the embodiment shown in Figure 7 and are respectively similar to Figures 2a to 2f, Figures 4a to 4f, or Figures 6a to 6f. Figure 8a shows the profile of the take-up cam 40. Figure 8b shows the profile of the exhaust cam 70. In the two-stroke compression release motor braking mode operation shown in FIG. the exhaust valve 60b is produced by the exhaust cam lobe 72b, while the exhaust valve opening 60x is produced by an initial portion of the intake cam lobe 42. Also in Figure 8c, the opening of the exhaust valve take-off valve 30x is produced by the initial portion of the exhaust cam lobe 72a, while the intake valve opening 30b is produced by the rear portion of the intake cam lobe 42. In the operation of the positive energy mode of four times shown in Figure 8d, the opening of the exhaust valve 60a is produced by the exhaust cam lobe 72a, while the intake valve opening 30b is produced by the intake cam lobe 42. ra The signals shown in Figure 8e are for two-stroke engine braking, while Figure 8f shows these traces of signals for operation of the four-stroke positive energy mode. In Figures 8e and 8f, the upper trace t120 is for the control of the valve 120 and the second trace t110 is for the control of the valve 110. In each case, the trace is low for the connection of the valve ports A and C. The third and fourth traces are for the control of valves 82 and 52, respectively. In each case the trace is low to close the associated valve, and high to open the associated valve. For the exhaust cam lobe 72b to produce the opening of the exhaust valve 60b in the two-stroke compression release engine braking mode (Figure 2c) the valve 82 is closed and the valve 120 is in its AB position during lobe 72b. For the initial portion of the exhaust cam lobe 72a to produce the opening of the intake valve 30x, the valve 82 is closed and the valve 120 is in its position A-C during this portion of the lobe 72a. This causes the pressurized hydraulic fluid to flow from the master piston 80 through the valve 120 (AC ports) and the conduit 122 to the secondary piston 58, thus opening the intake valve 30. As soon as a suitable opening 30x of the valve is produced When the valve 82 is opened, the valve 82 opens to release more hydraulic fluid pressure from the master piston 80 to the accumulator 22. Then, the valve 120 can also be reset to its position AB. The valve 82 can be closed again at any time after the exhaust cam lobe 72a. For the initial portion of the intake cam lobe 42 to produce the opening of the exhaust valve 60x, the valve 52 closes and the valve 110 is in its position AC during this portion of the lobe 42. This causes the pressurized hydraulic fluid of the master piston 50 flows through the valve 110 (AC ports) and the conduit 112 to the secondary piston 88, thereby opening the exhaust valve 60 as shown at 60x in Figure 8c. As soon as a suitable opening of the exhaust valve occurs, the valve 52 briefly opens to vent hydraulic fluid to the accumulator 22. This allows the exhaust valve 60 to close again. The valve 110 then returns to its position A-B and the valve 52 is closed again so that the remaining portion of the intake cam lobe 42 causes the intake valve 30 to open as shown at 30b in Figure 8c.

In Figure 8f, valves 110 and 120 remain in their positions A-B at all times. Similarly, valve 52 remains closed at all times. The valve 82 is closed at all times except for the exhaust cam lobe 72b when the valve 82 is open so that the exhaust valve 60 will not open in response to that lobe. Another embodiment is shown in Figure 10. Elements that are similar in the embodiments described above are again identified by the same reference numbers. Figures 11a to 11b refer to the embodiment shown in Figure 10 and are respectively similar to Figures 2a to 2f, Figures 4a to 4f, Figures 6a to 6f, or Figures 8a to 8f. Figure 11a shows the profile of the take-up cam 40. Figure 11b shows the profile of the exhaust cam 70. In the operation of the two-stroke compression release motor braking mode shown in Figure 11c, the opening of the exhaust valve 60b is produced by the intake cam lobe 42b, while the exhaust valve opening 60x is produced by an initial portion of the intake cam lobe 42. Also in Figure 11c, the exhaust opening the intake valve 30x is produced by the initial portion of the exhaust cam lobe 72a, while the intake valve opening 30b is produced by the latter portion of the intake cam lobe 42. In the operation of the power mode positive four-stroke that is shown in Figure 11 d, the opening of the exhaust valve 60a is produced by the exhaust cam lobe 72a, while the opening of the intake valve 30b is produced by the cam lobe Take 42. What The traces of signals shown in Figure 11e are for two-stroke engine braking, while Figure 11f shows these traces of signals for the operation of the four-stroke positive energy mode. In Figures 11e and 11f the upper trace t120 is for the control of the valve 120 and the second trace t110 is for the control of the valve 110. In each case, the trace is low for the connection of the valve ports A and B, and the trace is high for the connection of valve ports A and C. The third and fourth traces are for the control of valves 82 and 52, respectively. In each case, the trace is low to close the associated valve, and high to open the associated valve. For the intake cam lobe 42b to produce the opening of the exhaust valve 60b in the two-stroke compression release motor braking mode (Figure 11c) the valve 52 is closed and the valve 110 is in its AC position during lobe 42b. For the initial portion of the exhaust cam lobe 72a to produce the opening of the intake valve 30x, the valve 82 is closed and the valve 120 is in its position A-C during this portion of the lobe 72a. This causes the pressurized hydraulic fluid to flow from the master piston 80 through the valve 120 (AC ports) and the conduit 122 to the secondary piston 58, thus opening the intake valve 30. As soon as a suitable opening 30x of the valve is produced of intake, the valve 82 is opened to release more hydraulic fluid pressure from the master piston 80 to the accumulator 22. Then, the valve 120 can also be reset to its position AB. Then, the valve 120 can also be reset to its position A-B. The valve 82 can be closed again at any time after the exhaust cam lobe 72a. For the initial portion of the intake cam lobe 42a to produce the opening of the exhaust valve 60x, the valve 52 closes and the valve 110 is in its position A-C during this portion of the lobe 42a. This causes the pressurized hydraulic fluid from the master piston 50 to flow through the valve 110 (ports A-C) and the conduit 112 to the secondary piston 88, thereby opening the exhaust valve 60 as shown at 60x in Figure 11c. As soon as a suitable opening of the exhaust valve is produced, the valve 52 opens briefly to vent hydraulic fluid to the accumulator 22. This allows the exhaust valve 60 to close again. The valve 110 then returns to its position A-B and the valve 52 is closed again so that the remaining portion of the intake cam lobe 42a causes the intake valve 30 to open as shown at 30b in Figure 11c. In Figure 11f, valves 110 and 120 remain in their positions A-B at all times. In the same way, the valve 82 remains closed at all times. The valve 52 is closed at all times except during the exhaust cam lobe 42b when the valve 52 is opened so that the exhaust valve 30 will not open in response to that lobe. The control of the valves 52, 82, 110 and 120 shown in Figure 10 can be carried out by the control circuit 100, which can be a circuit similar to that described in the other embodiments of the invention. Another embodiment is shown in Figure 12. Elements that are similar in the embodiments described above are re-identified by the same reference numbers. Figures 13a to 13b refer to the embodiment shown in Figure 12 and are respectively similar to Figures 2a to 2f, Figures 4a to 4f, Figures 6a to 6f, Figures 8a to 8f and Figures 11a to 11f. Figure 13a shows the profile of the take-off cam 40 with the lobe 42. Figure 13b shows the profile of the exhaust cam 70 with the lobe 72a. Superposed in Figures 13a and 13b, respectively, in dashed lines, are the intake and exhaust cam profiles, 242 and 272, respectively. The profiles 242 and 272 can be originated with cams associated with other cylinders of the same motor 10c. In the operation of the two-stroke compression release motor braking mode shown in Figure 13c, the opening of the exhaust valve 60b can be produced by a remote intake of the exhaust cam lobe 242 or 272, while the opening of the exhaust valve 60x can be produced by an initial portion of the intake cam lobe 42. Also in Figure 13c, the opening of the intake valve 30x can be produced by the initial portion of the exhaust cam lobe 72a , while the intake valve opening 30b is produced by the rear portion of the intake cam lobe 42. With reference again to the opening 60b in Figure 13c, it should be noted that the opening 60b can be opened alternatively by any power source capable of providing the energy needed to open the exhaust valve at the right time. For example, with reference to Figure 12, the opening 60b could be produced by a hydraulic source stored in a common rail system associated with the engine 10c. The hydraulic force to open the exhaust valve for the opening 60b can be provided through the valve 140 from a hydraulic source 150 in the hydraulic conduit 112. Although the above discussion identifies the hydraulic source 150 providing the necessary energy to open the valve 60 to open 60b, it should be considered that alternative energy sources can be used without transgressing the intended scope of the invention. In the operation of the four-stroke positive energy mode shown in Figure 13d, the opening of the exhaust valve 60a is produced by the exhaust cam lobe 72a, while the opening of the intake valve 30b is produced by the take-up cam lobe 42. The traces of signals shown in Figure 13e are for two-stroke engine braking, while Figure 13f shows these traces of signals for operation of the four-stroke positive energy mode. In Figures 13e and 13f, the upper trace t140 is for the control of the valve 140, the trace t120 is for the control of the valve 120 and the trace t110 is for the control of the valve 110. In each case, the trace is low for the connection of valve ports A and B, and the trace is high for the connection of valve ports A and C. The fourth and fifth traces are for the control of valves 82 and 52, respectively. In each case the trace is low to close the associated valve, and high to open the associated valve. For the remote cam lobe 272 to produce the opening of the exhaust valve 60b in the two-stroke compression release engine braking mode (Figure 13c) the valves 82, 52 and 110 are closed, the valve 140 is open and valve 120 is in its AC position. For the initial portion of the exhaust cam lobe 72a to produce the opening of the intake valve 30x, the valve 82 is closed and the valve 120 is in its position A-C during this portion of the lobe 72a. This causes the pressurized hydraulic fluid to flow from the master piston 80 through the valve 120 (AC ports) and the conduit 122 to the secondary piston 58, thus opening the intake valve 30. As soon as a suitable opening 30x of the valve is produced of intake, the valve 82 is opened to release more hydraulic fluid pressure from the master piston 80 to the accumulator 22. Then, the valve 120 can also be reset to its position AB. The valve 82 can be closed again at any time after the exhaust cam lobe 72a. For the initial portion of the intake cam lobe 42 to produce the opening of the exhaust valve 60x, the valves 52 and 140 close and the valve 110 is in its AC position during this portion of the lobe 42. This causes the fluid Pressurized hydraulic master piston 50 flows through valve 110 (AC ports) and conduit 112 to secondary piston 88, thereby opening exhaust valve 60 as shown at 60x in Figure 13c. As soon as a suitable opening of the exhaust valve occurs, the valve 52 briefly opens to vent hydraulic fluid to the accumulator 22. This allows the exhaust valve 60 to close again. The valve 110 then returns to its position A-B and the valve 52 is closed again so that the remaining portion of the intake cam lobe 42 causes the intake valve 30 to open as shown at 30b in Figure 8c. It has been mentioned several times in the previous discussion that the control of valves such as 52, 82, etc. it can also be used to produce more subtle variations in timing of the motor valve, amount of opening of the motor valve, etc. the above-mentioned Application Serial Number 08 / 512,528, which shows and describes this principle in a somewhat related apparatus, has been incorporated herein by reference. Figures 9a-c, in the present also provide several examples of this principle. An illustrative motor cam profile is shown in Figure 9a. Several possible signals to control the firing of valves 52, 82, etc. they are shown in Figure 9b, which is synchronized with Figure 9a. These signals are identified respectively as a_, b, c, and d. The different openings of a motor valve such as 30 or 60 in response to the cam profile of Figure 9a and an associated trip valve controlled by the control signals of Figure 9b are shown in Figure 9c. For example, the motor valve opens as shown in a in Figure 9b. The signal a keeps the trip valve closed during the entire motor cam, causing the opening of the motor valve to follow the entire motor cam profile. As shown in b in Figure 9c, the motor valve opens by a smaller amount and closes earlier when the associated trip valve opens before the motor cam profile reaches its peak as shown by signal b in Figure 9b. As shown in c in Figure 9c, these trends are more pronounced when the associated trigger valve is opened even earlier as shown by the signal c in Figure 9b. As shown in d in Figure 9c, the opening of the motor valve can be delayed in relation to the start of the cam profile of the motor leaving the associated trip valve open until after the cam profile has started (see signal d in Figure 9b). Other examples of these types of engine valve opening modifications are shown and described in the aforementioned Application Serial Number 08 / 512,528 which has been incorporated by reference herein. The systems of this invention may have a number of additional advantages. The use of hydraulic lost motion to modify or eliminate certain positive cam movements and therefore alter timing of the engine valve and displacement can be useful to improve fuel economy in the positive operating mode. When closing certain motor valves in cold weather in positive operation mode, the system can be used as a motor heating device. During operation of the two-stroke engine braking mode, the engine exhaust valves can be opened to allow reverse flow of the exhaust handle to the engine cylinders. This supercharges the cylinders of the engine to increase the braking performance of the engine. Changing the timing of the exhaust valve in positive operation mode of the engine can also be used to recirculate exhaust gas and thus reduce particulate emissions. It will be understood that the foregoing is only illustrative of the principles of this invention and that various modifications may be made by those skilled in the art. For example, Figures 1, 3, 5, 7, 10 and 12 suggest that the engine has an intake and an exhaust valve 30 and 60 per engine cylinder. It is very common for the engines to have two intakes and two exhaust valves per cylinder, and it will be readily apparent that this invention is equally applicable to such engines.

Claims (6)

1. CLAIMS 1. An internal combustion engine, comprising: a intake valve associated with a cylinder of such engine; an exhaust valve associated with said cylinder; a take-up cam having a lobe synchronized with possible openings of such intake valve; an exhaust cam having a lobe synchronized with possible openings of such exhaust valve; a first hydraulic link containing hydraulic fluid operatively coupled between said intake cam and said intake valve to selectively respond to such intake cam lobes by causing said intake valve to open; a second hydraulic link containing hydraulic fluid operatively coupled between said exhaust cam and said exhaust valve to selectively respond to such exhaust cam lobes by causing said exhaust valve to open; a first hydraulic fluid control for selectively controlling the hydraulic fluid pressure in said first hydraulic link to selectively modify the openings of such intake valve in response to said intake cam lobes; and a second hydraulic fluid control for selectively controlling the hydraulic fluid pressure in said hydraulic second link to selectively modify the openings of such exhaust valve in response to said exhaust cam lobes.
2. 2. The apparatus defined in claim 1, wherein at least one of said hydraulic fluid controls comprises a valve for selectively releasing hydraulic fluid from the hydraulic link associated with that hydraulic fluid control. The apparatus defined in claim 2, wherein said valve is an electrically operated valve controlled by electronic control circuits. The apparatus defined in claim 1, further comprising: a sensor for monitoring an operating parameter of such an engine and for producing an output signal indicative of such parameter, whose output signal is applied to one of said control circuits of hydraulic fluid to cause said hydraulic fluid control to modify the operation of one of said hydraulic links in accordance with said parameter. The apparatus defined in claim 4, wherein said parameter includes an indication of whether said engine is going to be in positive operation mode or compression release motor braking mode. The apparatus defined in claim 5, wherein said hydraulic fluid control responds to said output signal of said sensor (1) by operating such valves to produce a four-stroke positive energy mode operation of said engine when said signal indicates that said motor will be in positive operation mode, and (2) operating such valves to produce has a single lobe. 11. The motor of claim 1 further comprising one or more additional lobes in such take-up cam. 12. The apparatus defined in claim 11, wherein at least one of said hydraulic fluid controls comprises a valve for selectively releasing hydraulic fluid from the hydraulic link associated with that hydraulic fluid control. The apparatus defined in claim 12, wherein said valve is an electrically operated valve controlled by electronic control circuits. The apparatus defined in claim 11, further comprising: a sensor for monitoring an operating parameter of such an engine and for producing an output signal indicative of such parameter, whose output signal is applied to one of said fluid controls hydraulic to make the said hydraulic fluid control modify the operation of one of such hydraulic links in accordance with said parameter. The apparatus defined in claim 14, wherein said parameter includes an indication of whether said engine is going to be in positive operating mode or compression release motor braking mode. 16. The apparatus defined in claim 15, wherein said hydraulic fluid control responds to said output signal of said sensor (1) by operating such valves to produce a four-stroke positive energy mode operation of such a motor when said signal indicates that said motor is going to be in mode of positive operation, and (2) operating such valves to produce a two-stroke compression release motor braking mode operation of such a motor when said signal indicates that said motor will be in motor brake release mode. compression. The apparatus defined in claim 11, wherein at least one of said hydraulic links comprises: a master piston that alternates in response to the lobe or lobes on the cam to which that hydraulic link is operatively coupled; and a secondary piston selectively alternating in response to the pressure and flow of hydraulic fluid in such a hydraulic link to selectively open the valve to which the hydraulic link is selectively coupled. The apparatus defined in claim 1, wherein said second hydraulic fluid control is selectively operable to allow said ext valve to remain fully closed in response to such a lobe on said ext cam and to open in response to such a lobe in the aforementioned escape cam. The apparatus defined in claim 11, wherein said first hydraulic fluid control is selectively operable to allow such intake valve to remain completely closed in response to any first such lobes on said intake cam and to be open in response to any second of the mentioned lobes in such take cam. The apparatus defined in claim 11, further comprising a remote cam synchronized with possible openings of such intake and ext valves.