JP2005516144A - Engine valve actuation system and method using reduced pressure common rail and dedicated engine valve - Google Patents

Abstract

Disclosed are systems and methods for operating engine valves that implement engine braking and / or exhaust gas circulation using a common hydraulic fluid source. This system receives high pressure hydraulic fluid, such as that used to provide fuel injection, from a common rail system. This hydraulic oil pressure is reduced before being used to operate the engine valve for engine braking or EGR. An engine valve dedicated to engine braking or EGR function is preferably provided in the engine. In an alternative embodiment, this dedicated engine braking / EGR valve can be driven by an electromagnetic actuator.

Description

  The present invention relates to a method and apparatus for operating an engine valve of an internal combustion engine to achieve a compression release braking event, a bleed engine braking event, and / or an exhaust gas internal circulation (EGR) event.

  During engine braking, an exhaust valve is selectively opened to convert the power generating internal combustion engine to a power absorbing air compressor at least temporarily. As the piston moves upward during its compression stroke, the gas trapped in the cylinder is compressed. The compressed gas opposes the upward movement of the piston. During engine braking operation, when the piston approaches top dead center (TDC), at least one engine valve in communication with the exhaust manifold is opened to release the compressed gas and stored in the compressed gas. This prevents the energy being returned to the engine in the next expansion / down stroke. By doing so, the engine produces a decelerating force that helps the vehicle decelerate.

  The operation of the compression-release engine braking described in the above sentence has been known for a long time. One of the earliest descriptions of systems used for compression release braking is provided by Cummins US Pat. No. 3,220,392. The system described in the Cummins 392 patent draws the movement to open a pair of exhaust valves for a compression release event from an existing intake, exhaust or injector pushrod or rocker arm. The compression release operation is transmitted to the bridge connecting the two exhaust valves by a hydraulic linkage that can be selectively extended from a push rod or rocker arm. The hydraulic link mechanism expands to transmit the compression release operation during the engine braking operation, and contracts to absorb such operation during the driving force operation. Due to this contraction of the hydraulic linkage during the drive operation, the compression release operation becomes “lost” during the drive force, and such a system is therefore commonly referred to as a “lost motion” valve actuation system.

  In a lost motion system such as the Cummins system, the engine valve is typically driven by a fixed shape cam, more specifically, one or more lobes fixed on each cam. Using a constant shape cam, the engine valve timing and / or lift magnitude required to optimize engine performance at various engine operating conditions, such as different engine speeds during engine braking. It becomes difficult to adjust the thickness.

  Over the years, various improvements have been made to the system and method described in the Cummins 392 patent. One such improvement is to operate one or more valves for engine braking using a common source of high pressure fluid, such as that used in fuel injection systems. Such systems are often referred to as “common rail” systems. In a common rail valve actuation system, a source of high pressure hydraulic fluid is selectively added to the actuator piston to actuate one or more valves for a compression release event. The valve selected for operation to apply engine braking is most commonly an exhaust valve. Examples of such systems are Sickler US Pat. No. 4,572,114, Pitch US Pat. No. 5,012,778, and Maistrick US Pat. Nos. 5,787,859, 5,809. 964, No. 6,082,328, each of which is incorporated herein by reference. Some common rail systems have dedicated auxiliary valves for engine braking. Examples of such systems are shown in Corte and other US Pat. No. 5,564,386, Schmidt and other US Pat. No. 5,609,134, and Bergman US Pat. No. 5,794,590. Each of which is incorporated herein by reference.

  The common rail system allows a virtually infinite adjustment of valve timing since a high pressure hydraulic fluid source is always available for valve operation. Since common rail systems can theoretically provide almost infinite changes in valve timing, they communicate with the appropriate manifold (eg, intake or exhaust manifold). As long as it is used, it can be used to perform almost any kind of engine valve event, such as intake, exhaust, compression release braking, bleed braking, or exhaust gas circulation (EGR). Therefore, if the use of this hydraulic pressure is controlled at high performance and speed, the common rail system should be able to provide valve actuation for various valve event requirements, as well as for lift and duration. Some control should also be provided.

  However, so far, common rail engine valve actuation systems used for braking and EGR have not been widely used. The necessary high performance control has not been realized effectively, especially in the seating of engine valves. Two problems that tend to preclude the use of common rail actuation systems are the high cost of components necessary to achieve the required level of control and the system becoming completely dysfunctional when the hydraulic pressure is reduced. It is easy to become. Until these problems are resolved, it is likely that the lost motion system will remain the mainstream system used for engine braking.

The aforementioned problems with common rail systems are partly due to the use of very high pressure sources to open engine valves and partly due to significant valve events, ie main intake and main exhaust. This stems from the reliability of the system performing the event. The proposal to use very high oil pressure for common rail engine braking stems from a plan to install the engine braking system on a common rail fuel injection system already installed in the vehicle. Yes. This “attachment” is believed to result in significant cost savings since only one high pressure source (and a set of components) is required for two systems: engine braking and fuel injection. Since fuel injection requires very high pressures on the order of 210 kg / cm ² (3000 psi), attempts have been made to provide a common rail system for engine braking that uses fluids of similar pressure. I came. However, the use of such high pressures necessitates the use of a very large force return spring for the actuating valve, which necessitates a complicated valve seating device. Furthermore, leakage is a greater problem in high pressure systems, and component design is inherently more important and expensive. Accordingly, there is a need for a common rail system that can be used for engine braking or EGR that does not suffer from the disadvantages associated with using high pressure fluids for common rail operation.

  A second important challenge arising from using a common rail system for engine valve operation is the potential for the system to malfunction. Hydraulic systems are prone to malfunction as a result of fluid leakage. The greater the degree of leakage prevention measures, the more expensive the system. Even if the common rail system is not capable of engine braking and / or EGR, the vehicle will work suboptimally without these functions, but is not itself catastrophic. However, loss of the main intake or main exhaust valve event is unacceptable as it results in overall engine malfunction. Accordingly, there is a need for a common rail system that is used only for engine braking and / or EGR valve events and is not required for main intake or main exhaust engine valve events.

  Applicants have addressed the various challenges described above by combining a reduced pressure common rail system or electromagnetic drive actuator with a dedicated engine braking / EGR engine valve. Effective use of the common rail system for braking and EGR has been realized. When the pressure is reduced, the ease of leakage and the influence of leakage are reduced, and the load on the valve mechanism is reduced. Furthermore, such a system can achieve near infinite timing changes for engine braking and internal EGR without jeopardizing main intake and exhaust valve operation.

  Some, but not necessarily all, further objects and advantages of the embodiments of the present invention are described in the following text of the description, and in part to those skilled in the art. / Or will become apparent from the practice of the invention.

  In response to the aforementioned challenges, Applicants have developed an innovative engine valve actuation system for engine braking and / or exhaust gas circulation. This includes a high pressure hydraulic oil source, a hydraulic oil pressure reducing device connected to the high pressure hydraulic oil source, a hydraulic oil control valve connected to the hydraulic oil pressure reducing device, and an engine valve actuator connected to the hydraulic oil control valve. .

  In one embodiment, the present invention comprises a high pressure hydraulic fluid passage, a high pressure hydraulic fluid source, a hydraulic fluid pressure reducing device connected to the hydraulic fluid source via the high pressure hydraulic fluid passage, a low pressure hydraulic fluid passage, and a low pressure hydraulic fluid. An engine valve operating system comprising a hydraulic control valve connected to a hydraulic pressure reducing device through a passage, an actuator hydraulic passage, and an engine valve actuator for generating an engine valve event. The valve actuator communicates with the hydraulic oil control valve via the actuator hydraulic oil passage.

  In another embodiment, the invention is a method of operating an engine valve of an internal combustion engine to generate an engine valve event. The method includes supplying hydraulic oil to a hydraulic oil pressure reducing device, reducing the hydraulic oil pressure from a first pressure to a second pressure, and selectively supplying the hydraulic oil to an engine valve actuator. And applying an engine valve to generate an engine valve event.

  It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification by reference, illustrate specific embodiments of the invention and, together with the detailed description, clarify the principles of the invention. Useful.

  BRIEF DESCRIPTION OF THE DRAWINGS To facilitate an understanding of the present invention, reference will now be made to the accompanying drawings, wherein like reference numerals designate like elements. The drawings are for illustration only and should not be construed as limiting the invention.

  Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Referring to FIG. 1, a valve actuation system 10 for an internal combustion engine is shown. In one embodiment, the valve actuation system 10 includes a high pressure hydraulic oil source 100, a hydraulic oil pressure reducing device 300 connected to the high pressure hydraulic oil source 100, a hydraulic oil control valve 400 connected to the hydraulic oil pressure reducing device 300, And an engine valve actuator 600 connected to the hydraulic oil control valve 400 for operating the engine valve 700. The engine valve 700 can include a dedicated braking valve. However, it is also contemplated that engine valve 700 may include an exhaust valve and / or an intake valve.

  In another embodiment of the present invention shown in FIG. 2, the valve actuation system 10 further includes a pressure accumulation tank 500 connected to the hydraulic fluid control valve 400 and a low pressure hydraulic fluid tank 200 connected to the high pressure hydraulic fluid source 100. be able to.

  Referring to FIG. 3, in one embodiment of the present invention, valve actuation system 10 includes a high pressure hydraulic source 100 that can be used to supply a common rail fuel injection system. A hydraulic electronic unit injection (HEUI) system commercially available from Navista International is an example of such a common rail fuel injection system.

The high pressure hydraulic oil source 100 includes a high pressure pump 110, a pressure controller 120, and a high pressure space 130. The high pressure hydraulic oil pump 110 sucks hydraulic oil such as diesel fuel from the low pressure tank 200. The hydraulic oil pressure supplied by the pump 110 is about several hundred kg / cm ² (for example, 210 kg / cm ² (3000 psi)). High pressure hydraulic oil source 100 is well known in the art of fuel injection systems. The pressure supplied by the high pressure hydraulic oil source 100 is indicated by pressure P1.

In the embodiment of the invention shown in FIG. 3, the high pressure oil supplied by the hydraulic oil source 100 can be used not only to provide fuel injection but also to provide a power source for engine braking operations. One advantage of using a high pressure hydraulic fluid source, such as hydraulic fluid source 100, for engine braking is that it already exists in the engine. In order to use the high pressure hydraulic oil source 100 for the purpose of engine braking, the pressure oil from the high pressure hydraulic oil source 100 is supplied to the decompression device 300 via the high pressure line 140. The decompressor 300 reduces the hydraulic oil pressure, preferably by an order of magnitude, more preferably to a level of about 21 kg / cm ² (300 psi). The decompressed hydraulic oil is supplied to the control valve 400 via the pipe line 310. The pressure supplied by the decompression device 300 is indicated by pressure P2.

  In one embodiment, the pressure reducing device 300 includes a pressure reducing valve. The pressure reducing device 300 includes a direct acting pressure reducing valve, a two-way pilot operated pressure reducing valve, and / or any other known pressure reducing valve. As will be apparent to those skilled in the art, other pressure reducing devices adapted to reduce the pressure of hydraulic fluid from the high pressure hydraulic oil source 100 are recognized as being within the scope and spirit of the present invention.

  With continued reference to FIG. 3, the control valve 400 includes a valve body 410 and a controller 420. Valve body 410 is preferably a 3 / 2-way control valve and includes an internal passage that connects first port 412 with second port 414 and third port 416 with fourth port 418. . The valve body 410 is biased to the initial position by the control valve spring 430.

  In the initial position, an internal passage in the valve body 410 connects the brake / actuator line 440 with the pressure accumulation tank 500. In the alternative embodiment shown in FIG. 4, the accumulator tank 500 can be replaced with a vent or hydraulic oil return line that connects the control valve 400 to the low pressure tank 200.

  The controller 420 can be used to move the valve body 410 so that the working fluid flows into and out of the brake actuator line 440. In FIG. 3, the valve body 410 can move linearly toward the control valve spring 430. The controller 420 may be any device that is suitable for moving the valve body 410 at high speed. The controller 420 may be a hydraulic, hydroelectric, mechanical, piezoelectric, or electromagnetic (ie, solenoid) device. The controller 420 is preferably capable of moving the valve body 410 at least once, preferably more than once per engine cycle.

  More preferably, it is understood that the controller 420 is controlled by electrical signals generated by an engine control module (ECM) (not shown). As will be apparent to those skilled in the art, the ECM includes a microprocessor and is coupled to other engine components such as, for example, an engine cylinder, exhaust manifold, intake manifold, or any other engine component. To control the controller 420.

  The brake actuator line 440 allows fluid communication between the control valve 400 and the engine valve actuator 600. Engine valve actuator 600 includes a hydraulic fluid chamber 610, an actuator piston 620 slidably mounted within the hydraulic fluid chamber, and a return spring 630.

  However, although the return spring 630 is shown in the hydraulic oil chamber 610, it can be installed at any position between the engine valve actuator 600 and the engine cylinder (not shown). The return spring 630 can also be installed as a return spring for a dedicated braking valve 700. This is because when the dedicated braking valve 700 returns to its uppermost position, the actuator piston 620 also returns to its uppermost position.

  The actuator piston 620 can be terminated at the top of the engine valve, or alternatively, the engine valve 700 dedicated to braking and / or exhaust gas circulation functions can be activated. Engine valve 700 provides selective communication between engine cylinder 720 and exhaust manifold 710. The return spring 630 biases the actuator piston 620 toward the upper end of the hydraulic oil chamber 610. In this position, the dedicated engine valve 700 is closed.

  The control valve 400 can assume two main positions under the action of the controller 420. The first position of the control valve 400 corresponds to a situation where no engine braking and / or exhaust gas circulation is required. That is, the dedicated engine valve 700 is closed. When the dedicated engine valve 700 is to be closed, the controller 420 holds the valve body 410 in the position shown in FIG. In this position, the first port 412 of the valve body 410 communicates with the brake / actuator conduit 440, and the second port 414 communicates with the pressure accumulation tank 500. As a result, the valve body 410 provides communication between the hydraulic oil chamber 610 and the accumulator tank 500. The hydraulic oil pressure in the accumulator tank 500 is low, so a dedicated engine valve return spring (which can be a spring 630) displaces the actuator piston 620 upwards, pushing the hydraulic oil out of the hydraulic oil chamber 610 and accumulating tank. Push into 500. Since the control valve 400 is not in a position that provides communication between the pressure reducing line 310 and the brake / actuator line 440, no new hydraulic fluid flows into the hydraulic fluid chamber 610, so the actuator piston 620 is moved downward. It cannot be displaced.

  When engine braking and / or exhaust gas circulation is desired, depressurized hydraulic fluid is added from the control valve 400 to the actuator piston, causing the actuator piston 620 to be displaced downwards and operating the dedicated engine valve 700. Let When actuator piston 620 is displaced downward toward dedicated engine valve 700, the dedicated engine valve opens and gas freely flows between the engine cylinder connected to the dedicated engine valve and the exhaust manifold.

  Initially, a system for braking, EGR, or other valve operating load can be turned “on” by supplying a reduced hydraulic fluid pressure from the pressure reducing device 300 into the pressure reducing line 310. After hydraulic fluid pressure is present in the pressure reducing line 310, the controller 420 is instructed to move the valve body 410 downward. This downward movement aligns the third port 416 of the valve body with the pressure reducing line 310 and the fourth port 418 with the braking actuator line 440. In this position, valve body 410 provides fluid communication between pressure reducing line 310 and brake actuator line 440. This communication causes the actuator piston 620 to move downward and the engine valve 700 to open, allowing an engine braking or exhaust gas circulation event.

  The opening and closing cycle of the engine valve 700 described above can be performed as quickly as the controller 420 can drain and refill hydraulic fluid from the hydraulic fluid chamber 610. Obviously, the speed of the system depends on the speed and size of the control valve 400, the size and length of the brake actuator line 440, and the viscosity of the hydraulic fluid. Therefore, it is advantageous to keep the control valve 400 as close as possible to the hydraulic fluid chamber 610 to improve system response time. In some embodiments of the present invention, the system is capable of more than one engine valve event per engine cycle and the system is open, closed, and has a duration of braking and almost no EGR event. It is desirable to be able to select an infinite variety of timings. While it is desirable that the system be capable of high speed operation, it is not always necessary to operate at high speed in order to produce advantageous results. For example, the system 10 provides partial or full cycle bleed braking during times when braking noise is a problem (in a city or city) and compression at other times when noise is not a problem. Can be used to provide release type braking.

For operation of the dedicated engine braking valve 700, vacuum hydraulic fluid pressure ^(i.e., 210 kg / cm 2 (3000 psi) rather ^than, 21 kg / cm 2 (300 psi) or so) Using several advantages Sometimes. An advantage realized during braking and / or EGR is that the high speed trigger valve used as the control valve 400 is easier to manufacture and more reliable because only depressurized hydraulic fluid needs to be handled. is there. The use of reduced pressure hydraulic fluid also reduces the impact load and seating speed of the braking components and makes such load and speed more controllable. Furthermore, the use of reduced pressure hydraulic fluid can reduce hydraulic fluid leakage, reduce vibration of the braking system, and make the entire system more compact. Benefits realized during driving forces include near infinite valve timing changes to achieve internal EGR that closely matches engine speed and / or load. The system 10 can also be modified to provide a cooled internal EGR because the outlet passage of the dedicated valve can be different from that of the main exhaust valve and a cooler can be placed in the dedicated passage. can do.

  An alternative embodiment of the present invention is shown in FIG. 5, where like reference numerals indicate like elements. In the system shown in FIG. 5, the engine valve actuator 600 is provided by an electromagnetic actuator 690. In this embodiment, a common rail system is not required as in the system of FIG. In all other respects, the system of FIG. 5 can operate similarly to the system shown in FIG.

  In one embodiment, the electromagnetic actuator 690 can include a high speed solenoid valve that can operate the engine valve 700 at a rate of at least once per engine cycle. In another embodiment, the electromagnetic actuator 690 can include a low speed solenoid valve. Other embodiments of the engine valve actuator 600, including but not limited to piezoelectric actuators, are also considered within the scope and spirit of the present invention.

  The dedicated engine valve 700 for engine braking and EGR is smaller than the main exhaust valve and can be opened with less force. After the valve is fully opened, the flow area through the valve is controlled by the annular gap between the inner diameter and the valve stem, and the force required to keep the valve open is further reduced.

  It will be apparent to those skilled in the art that changes and modifications can be made to the present invention without departing from the scope and spirit of the invention. For example, the relative pressures of the high pressure system and the reduced pressure system may differ from the pressures referred to in the above discussion without departing from the intended scope of the present invention. The size and design of the individual components can be varied, and some components such as pressure accumulator tanks, pressure sensors, etc. can be eliminated without departing from the intended scope of the present invention. Further, the design of the control valve 400 can be changed without departing from the intended scope of the present invention. Furthermore, the hydraulic fluid used can be changed without departing from the intended scope of the present invention. Embodiments of the method and apparatus of the present invention are also applicable to two-stroke engine braking, which is a modification of normal engine exhaust and intake valve events, as well as four-stroke engine braking. Accordingly, the present invention is intended to embrace all such alterations and modifications of this invention provided they come within the scope of the appended claims and their equivalents.

1 is a block diagram of an engine valve operating system according to a first embodiment of the present invention. FIG. 3 is a block diagram of an engine valve operating system according to a second embodiment of the present invention. FIG. 5 is a schematic view of an engine valve operating system according to a third embodiment of the present invention. FIG. 6 is a block diagram of an engine valve operating system according to a fourth embodiment of the present invention. FIG. 7 is a schematic view of an engine valve operating system according to a fifth embodiment of the present invention.

Claims (20)

A high-pressure hydraulic fluid passage;
A high pressure hydraulic oil source;
A hydraulic oil pressure reducing device connected to the hydraulic oil source via the high-pressure hydraulic oil passage;
A low pressure hydraulic fluid passage;
A hydraulic oil control valve connected to the hydraulic oil pressure reducing device via the low pressure hydraulic oil passage;
An actuator hydraulic fluid passage;
An engine valve actuator in communication with the hydraulic fluid control valve via the actuator hydraulic fluid passage for operating an engine valve to generate an engine valve event;
Engine valve operating system.   The system of claim 1, wherein the engine valve event is selected from the group consisting of a compression release braking event, an bleed braking event, and an exhaust gas circulation event.   The system of claim 1, wherein the hydraulic oil source comprises a fuel injection system.   The system of claim 1, wherein the hydraulic oil pressure reducing device reduces the hydraulic oil pressure from a first pressure to a second pressure that is approximately an order of magnitude lower than the first pressure. The system of claim 4, wherein the second pressure is on the order of 21 kg / cm ² (300 psi). The control valve
A valve body adapted to selectively move between a first operating position and a second operating position, and having a plurality of hydraulic oil passages therein;
A controller for moving the valve body;
The system of claim 1, comprising a spring that biases the valve body to a first operating position.   The system of claim 6, wherein the control valve moves the valve body at a rate of at least once per engine cycle.   The system of claim 6, further comprising an accumulator tank, wherein the control valve connects the actuator hydraulic fluid passage to the accumulator tank when the valve body is in the first operating position.   The system of claim 6, wherein the control valve connects the actuator hydraulic passage to a low pressure hydraulic oil tank when the valve body is in the first operating position.   The system of claim 6, wherein the control valve connects the actuator hydraulic passage to a low pressure hydraulic passage when the valve body is in the second operating position. The engine valve actuator is
A hydraulic fluid chamber for receiving hydraulic fluid from the actuator hydraulic fluid passage;
An actuator piston slidably mounted in the hydraulic oil chamber;
The system of claim 1, comprising a return spring in contact with the actuator piston. Further comprising a low pressure hydraulic oil tank, wherein the hydraulic oil source comprises:
A high pressure pump in communication with the low pressure hydraulic oil tank;
A pressure controller;
The system of claim 1, further comprising a high pressure space connected to the high pressure hydraulic fluid passage.   The system of claim 1, wherein the engine valve is a dedicated engine exhaust valve.   The system of claim 1, wherein the engine valve operates with less force than a main exhaust valve. A high pressure hydraulic oil source for supplying hydraulic oil at a first pressure;
A hydraulic oil pressure reducing device connected to the hydraulic hydraulic oil source;
A hydraulic oil control valve having a first operational position and a second operational position and connected to the hydraulic oil pressure reducing device;
An engine valve adapted to receive the hydraulic oil at a second pressure when the hydraulic oil control valve is in the second operating position to operate the engine valve to generate an engine valve event. Including actuators,
Engine valve operating system. The system of claim 15, wherein the second pressure is in the order of 21 kg / cm ² (300 psi). A method for operating an engine valve of an internal combustion engine to generate an engine valve event, comprising:
Supplying hydraulic oil to the hydraulic oil pressure reducing device;
Reducing the hydraulic oil pressure from the first pressure to the second pressure;
Selectively applying hydraulic oil to the engine valve actuator at a second pressure;
Actuating an engine valve to generate an engine valve event.   The method of claim 17, wherein the actuating an engine valve further comprises generating a compression release braking event.   The method of claim 17, wherein the actuating the engine valve further comprises generating an bleed braking event.   The method of claim 17, wherein the actuating the engine valve further comprises generating an exhaust gas circulation event.

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