Heavy-duty engine with air cylinder capable of being switched between single-valve driving and double-valve driving

Abstract

The invention relates to the field of piston type internal combustion engines. According to the heavy-duty engine, the air cylinder can be switched between single-valve driving and double-valve driving, and the cam component with the unique cam profile is arranged; the cam component is combined with the control assembly, so that the continuous variable hydraulic valve mechanism can be switched between single-valve driving and double-valve driving; meanwhile, by arranging a plurality of valve components located at different positions in the control assembly, the exhaust main lift of double valves or cylinder deactivation, compression release braking of a single valve and advanced opening and closing of an exhaust valve are further achieved.

Description

Technical Field

[0001] The present invention relates to the field of piston internal combustion engines, and particularly to a heavy-duty engine whose cylinder can be switched between single-valve drive and dual-valve drive. Background Art

[0002] Currently, most mainstream heavy-duty engines use a single overhead cam SOHC (there is only one camshaft above the valves to drive the intake and exhaust valves) for the exhaust valve mechanism, and the exhaust valve is driven by a rocker arm.

[0003] A heavy-duty engine (internal combustion engine) may include a compression release function to provide auxiliary braking power for the vehicle. The compression release function is to open the exhaust valve before the top dead center (TDC point) of the piston, so that the gas is released under the cylinder pressure (such as above 30 barA). During the compression release process, the reciprocating piston does negative work, thereby achieving the effect of generating braking torque.

[0004] In recent years, a much-concerned commercial vehicle engine thermal management is waste heat management, that is, actively heating the selective catalytic reduction SCR of nitrogen oxides during cold start and low-load cycles. For future Euro 7 (EU7) exhaust emission regulations, actively reducing raw nitrogen oxide emissions and actively heating the aftertreatment device are one of the development roadmaps for many commercial vehicle engine manufacturers.

[0005] In terms of the preheating measures for the exhaust gas catalytic device, engine manufacturers have studied the method of directly using waste gas energy to actively heat the aftertreatment path at idle speed. For example, in a double overhead cam engine, the exhaust cam phase realizes early opening and early closing, so that hotter exhaust gas flows to the catalyst. The effect of early closing is to increase the residual combustion gas in the cylinder, which helps to increase the average temperature of the cylinder gas. However, for a single overhead engine without the cam phase adjustment function, the active exhaust path temperature increase must be achieved through valve lift switching.

[0006] In view of this, it is necessary to provide an integrated valve mechanism for a heavy-duty engine to solve the above problems. Summary of the Invention

[0007] The purpose of the present invention is to provide a heavy-duty engine whose cylinder can be switched between single-valve drive and dual-valve drive. The heavy-duty engine combines a cam member with a control component, so that the continuously variable hydraulic valve mechanism can be switched between single-valve and dual-valve drive.

[0008] To achieve the above-mentioned invention object, the present invention provides a heavy-duty engine in which a cylinder can be switched between single-valve drive and double-valve drive, which includes a hydraulic circuit and a continuously variable hydraulic valve mechanism. The continuously variable hydraulic valve mechanism is correspondingly arranged for each cylinder in the heavy-duty engine and includes: a piston assembly, including a pump unit and a cam member drivingly connected to the pump unit; an energy storage assembly; a valve return braking assembly, including a pair of arranged braking units, two exhaust units correspondingly arranged with the braking units, and a mechanical valve bridge assembly arranged between the braking units and the exhaust units; a control assembly, including a first control valve arranged between the energy storage assembly and the piston assembly; a second control valve arranged at one end of the valve return braking assembly, and a third control valve arranged between the hydraulic circuit and the continuously variable hydraulic valve mechanism; the mechanical valve bridge assembly includes a single-valve piston connected in any one of the braking units and a mechanical valve bridge connected in the other braking unit. The third control valve can control the second control valve to transmit the movement of the cam member to the single-valve piston, so as to drive only the valve stem of one exhaust unit, so that the corresponding cylinder works in the single-valve drive mode; the third control valve can also control the second control valve to transmit the movement of the cam member to the mechanical valve bridge, so as to drive the valve stems of two exhaust units, so that the corresponding cylinder works in the double-valve drive mode.

[0009] Optionally, the pump unit includes a pump roller abuttingly connected to the cam member, a pump piston connected to one end of the pump roller, a pump oil chamber for accommodating the pump piston, and a pump spring sleeved on the outer periphery of the pump piston.

[0010] Optionally, the outer peripheral edge of the cam member is formed with a first driving protrusion and a second driving protrusion arranged at intervals. The first driving protrusion has 3 continuous ramp-up steps and 1 ramp-down step, and the 3 ramp-up steps and the 1 ramp-down step together cover a crank angle of 470 degrees.

[0011] Optionally, the second driving protrusion is located between the crank angles of 480 to 600 degrees on the outer periphery of the cam member for braking gas recirculation.

[0012] Optionally, the energy storage assembly is connected to the first control valve through an intermediate pressure chamber or a first channel; the energy storage assembly includes an accumulator oil chamber, an accumulator piston movably connected in the accumulator oil chamber, and an accumulator spring sleeved on the outer periphery of the accumulator piston. The accumulator spring acts on the accumulator piston and tends to make the oil in the accumulator oil chamber flow to the intermediate pressure chamber or the first channel.

[0013] Optionally, the first control valve can control the communication or disconnection between the pump oil chamber and the accumulator oil chamber.

[0014] Optionally, the first control valve is a 2 / 2 normally open solenoid valve; the second control valve is a 3 / 2-way mechanical valve; the third control valve is a pilot-operated 3 / 2-way solenoid valve.

[0015] Optionally, the braking unit includes a piston unit. The single-valve piston can interact with the piston of the piston unit of one braking unit, and the piston of the piston unit of the other braking unit is connected to the mechanical valve bridge. The single-valve piston is movably connected to the mechanical valve bridge, so that the single-valve piston can move relative to the mechanical valve bridge to drive the valve stem of an exhaust unit to move. When the mechanical valve bridge moves, it can drive the valve stems of two exhaust units to move simultaneously.

[0016] Optionally, by switching the connection state of the hydraulic circuit, the second control valve can make it so that: the movement of the cam member causes the oil in the oil pumping chamber to enter the piston unit of one braking unit, thereby driving the valve stem of an exhaust unit to move via the single-valve piston, and the mechanical valve bridge does not move; or the movement of the cam member causes the oil in the oil pumping chamber to enter the piston unit of the other braking unit, thereby driving the mechanical valve bridge to move, and the mechanical valve bridge drives the valve stems of two exhaust units to move. The beneficial effects of the present invention include: The heavy-duty engine of the present invention combines a cam member with a control assembly, enabling the continuously variable hydraulic valve mechanism to switch between single-valve and dual-valve drive.

[0017] In addition, by providing a control assembly that includes a plurality of valve members located at different positions, the main exhaust lift or cylinder deactivation of the dual-valve, as well as the compression release braking, early opening, and early closing of the exhaust valve of the single-valve, are further realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of the continuously variable hydraulic valve mechanism for a heavy-duty engine of the present invention.

[0019] Figure 2 is Figure 1 a schematic structural diagram of the cam member in

[0020] Figure 3 is the lift curve in the main exhaust lift state.

[0021] Figure 4 is a schematic diagram of the state of the main exhaust lift continuously variable hydraulic valve mechanism and the control assembly in the normal ignition mode.

[0022] Figure 5 is the control strategy of the main exhaust lift control assembly and the cylinder pressure curves in the normal ignition mode and at the main lift.

[0023] Figure 6Schematic diagram of the single-valve operation state when the compression release brake CRB1.0 or the early exhaust valve opens / closes.

[0024] Figure 7 Control strategy of the control component in the early opening and early closing modes of the air valve and the cylinder pressure curve in the corresponding modes.

[0025] Figure 8 Schematic diagram of the operation state of the control device for the valve stop movement.

[0026] Figure 9 Control strategy of the control component in the compression release brake function mode and the cylinder pressure curve in the corresponding mode. Detailed implementation manners

[0027] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as a limitation to the present invention.

[0028] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0029] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed" and other terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be described in detail below with reference to the drawings and specific embodiments.

[0031] The current mainstream exhaust valve mechanism of heavy-duty engines can usually only achieve one valve lift function. The variable valve mechanisms of most heavy-duty engines switch between different rocker arms. To provide more than two valve lift functions, independent rocker arms are required for switching. The mechanical strength of the switching mechanism plays a decisive role in the change of valve lift. Its disadvantage is that the combination of multiple rocker arms or cams will occupy valuable engine installation space.

[0032] One challenge faced by the compression release function is the cam torque required for the camshaft to push the exhaust valve open. The braking force is usually characterized by the peak cylinder pressure. If two valves are opened when the cylinder pressure is high, the torque required to drive the camshaft may be twice that when opening one valve.

[0033] Therefore, if two valves need to be opened simultaneously during the compression release process, the camshaft material and timing chain must withstand very high torques (e.g., greater than 200 Nm), or the cylinder pressure must be reduced by means such as throttling or the turbocharger wastegate.

[0034] If only one exhaust valve needs to be opened, the camshaft torque will be reduced, while the in-cylinder pressure can still be greater than 60 barA. To switch between a single exhaust valve and a double exhaust valve, the movement of the single exhaust valve and the mechanical valve bridge can be hydraulically activated or deactivated.

[0035] In fact, the researchers found that the compression release brake, the main lift of the exhaust valve, and the early opening / closing can be integrated by setting the cam profile of the cam member, and then by calibrating the rotation trajectory of the cam member and cutting off the hydraulic pressure between the cam member and the exhaust valve plunger, continuous changes in valve lift can be achieved. That is to say, the ability of the high-speed solenoid valve can be fully utilized to transfer or not transfer the cam trajectory to the valve lift.

[0036] In view of this, the present invention provides a heavy-duty engine, which includes a continuously variable hydraulic valve mechanism, and the continuously variable hydraulic valve mechanism is provided corresponding to each cylinder in the heavy-duty engine.

[0037] Please refer to Figure 1 As shown, in the present application, the continuously variable hydraulic valve mechanism includes a piston assembly 1, an energy storage assembly 2, a valve return braking assembly 3, and a control assembly 4 for controlling the operation of the piston assembly 1, the energy storage assembly 2, and the valve return braking assembly 3.

[0038] The piston assembly 1 includes a cam member 11 and a pump unit 12 that is drivingly connected to the cam member 11. As Figure 2As shown, the outer peripheral edge of the cam member 11 is formed with a first drive projection 111 and a second drive projection 112 arranged at intervals. The first drive projection 111 has 3 consecutive ramp-up steps (i.e., the 1st ramp-up step 1a, the 2nd ramp-up step 1b, and the 3rd ramp-up step 1c) and 1 ramp-down step (1d). The 3 ramp-up steps and 1 ramp-down step (1d) together cover a crank angle CrA of 470 degrees (i.e., equivalent to a cam angle of 0 to 235°).

[0039] The second drive projection 112 is located between a crank angle CrA of 480 to 600 degrees on the outer periphery of the cam member 11 (i.e., equivalent to a cam angle of 0 to 60°) for braking the exhaust gas recirculation BGR and further enhancing the decompression braking power.

[0040] Furthermore, the pump unit 12 includes a pump roller 121 abutted against the outer peripheral edge of the cam member 11, a pump piston 122 connected to one side of the pump roller 121, a pump oil chamber 123 for accommodating the pump piston 122, and a pump spring 124 sleeved on the outer periphery of the pump piston 122. The pump unit 12 further includes a high-pressure oil chamber or a second passage 13 connected to the pump oil chamber 123. The pump spring 124 presses the pump piston 122 towards the cam member 11.

[0041] The energy storage assembly 2 is connected to the control assembly 4 through an intermediate pressure chamber or a first passage 21, and then is respectively connected to the piston assembly 1 and the valve return braking assembly 3 through the control assembly 4. The energy storage assembly 2 includes an accumulator oil chamber 22, an accumulator piston 23 movably connected in the accumulator oil chamber 22, and an accumulator spring 24 sleeved on the outer periphery of the accumulator piston 23. The intermediate pressure chamber or the first passage 21 is connected to the accumulator oil chamber 22, and the accumulator spring 24 acts on the accumulator piston 23 to tend to make the oil in the accumulator oil chamber 22 flow towards the intermediate pressure chamber or the first passage 21.

[0042] The valve return braking assembly 3 includes a pair of braking units 31, 31', corresponding exhaust units 32, 32' arranged corresponding to the braking units 31, 31', and a mechanical valve bridge assembly 33 arranged between the braking units 31, 31' and the exhaust units 32, 32'. Among them, the exhaust units 32, 32' include exhaust valves and valve stems 321, 321' and exhaust valve springs 322, 322' sleeved on the outer periphery of the valve stems; the exhaust valve springs 322, 322' apply a force ( Figure 1 in this case, pressing the valve stems 321, 321' upward) to make the valve stems 321, 321' tend to move upward. Here, only the exhaust valve springs 322, 322' are schematically shown. Figure 1In [the structure], the upper ends of the exhaust valve springs 322 and 322' can act on the lower surfaces of the flanges on the valve stems 321 and 321', and the lower ends of the exhaust valve springs 322 and 322' can be supported on the housing (for example, the cylinder head or the supporting part thereon). Further, the mechanical valve bridge assembly 33 includes a single valve piston 331 connected in any one of the braking units 31 and a mechanical valve bridge 332 connected in the other braking unit 31.

[0043] The control assembly 4 is a valve assembly for controlling the driving and conduction of the piston assembly 1, the energy storage assembly 2, and the valve return braking assembly 3. In this application, the control assembly 4 includes a first control valve 41 disposed between the energy storage assembly 2 and the piston assembly 1, and the first control valve 41 can control the connection or disconnection between the pump oil chamber 123 and the accumulator oil chamber 22. The control assembly 4 further includes a second control valve 42 disposed at one end of the valve return braking assembly 3; further, the two braking units 31 and 31' are connected to the second control valve 42 through two first hydraulic passages 421 and are switched through the second control valve 42, that is, at the same time, only one of the braking units 31 and 31' can be driven hydraulically.

[0044] The control assembly 4 further includes a third control valve 43 disposed between the hydraulic circuit 5 of the heavy-duty engine and the continuously variable hydraulic valve mechanism; then, the third control valve 43 is used to control the switching between the single-valve drive and the double-valve drive of the cylinder.

[0045] It should be noted that in this application, the hydraulic circuit 5 is connected to the third control valve 43 through a second hydraulic passage 50. The hydraulic circuit 5 includes an oil pump unit 51, a first oil passage 52 for connecting the oil sump 6 of the heavy-duty engine and the third control valve 43, and a second oil passage 53 for connecting the oil sump 6 of the heavy-duty engine and the oil pump unit 51. In this application, the third control valve 43 is a pilot-operated 3 / 2-way solenoid valve, and the third control valve 43 is disposed outside the cylinder head of the cylinder to control the second control valve 42 of each cylinder; preferably, the first control valve is a 2 / 2-way normally open solenoid valve; the second control valve is a 3 / 2-way mechanical valve.

[0046] The second control valve 42 can be arranged on the exhaust valve of each engine cylinder head, and only one third control valve 43 can be provided. One third control valve 43 can be connected to the second control valve 42 of each engine cylinder head through an oil passage.

[0047] For a better understanding of the continuously variable hydraulic valve mechanism for a heavy-duty engine of the present invention, the following description part will detail the motion states of each component in the continuously variable hydraulic valve mechanism for a heavy-duty engine during the working process.

[0048] Refer to Figure 2 And in combination with Figure 3As shown, in a four-stroke internal combustion engine, the first ramp-up step 1a of the first driving projection 111 of the cam member 11 covers the first compression release brake of the engine, which starts at 50 - 60 CrA degrees (crank angle) before TDC ignition and ends at the high point 3 - 5 CrA after 0 TDC ignition.

[0049] The second ramp-up step 1b of the first driving projection 111 of the cam member 11 starts from the end point of the first ramp-up step 1a, i.e., 3 - 5 CrA after TDC ignition and up to 70 CrA of ATDC, and then reaches 90 CrA of ATDC. The second ramp-up step 1b includes opening the exhaust valve in advance in the ignition mode so as to release the exhaust gas energy to the backward processing path earlier compared with the normal main lift mode.

[0050] The third ramp-up step 1c of the first driving projection 111 of the cam member 11 is the longest ramp-up stage, covering the main lift opening sequence. It starts to gradually accelerate from 90 CrA ATDC to 230 - 235 CrA ATDC.

[0051] The ramp-down step 1d of the first driving projection 111 of the cam member 11 returns to the base circle of the cam member 11. It starts from the ramp end of the third ramp-up step 1c and ends between 410 - 415 CrA ATDC.

[0052] The fourth ramp-up step of the cam member 11 is the ramp-up step 1e of the second driving projection 112, which functions to brake the exhaust gas recirculation BGR. It starts from 480 CrA ATDC and ends at 600 CrA ATDC; the lift height of the exhaust gas recirculation braking part should be less than 2 mm so that no cavitation occurs in the oil flow when the cam member 11 moves back to the base circle position during the ramp-down process.

[0053] Please refer to Figure 4 As shown, this is the valve bridge operation of the continuously variable hydraulic valve mechanism of the present invention for the exhaust main lift in the normal ignition mode; at this time, the first control valve 41 is energized, the third control valve 43 is de-energized, and the ramp-up phase on the cam member 11 is transmitted to the mechanical valve bridge 332, pushing the two exhaust units 32, 32' downward to open the cylinder exhaust passage; the braking unit 31 and the single valve piston 331 remain in the reference position without moving. That is, the third control valve 43 can control the second control valve 42 to transmit the movement of the cam member 11 to the mechanical valve bridge 332 so as to drive the valve stems of the two exhaust units, enabling the corresponding cylinder to work in the dual-valve drive mode.

[0054] Furthermore, refer to Figure 5 and in combination with Figure 2 、 Figure 4As shown, the first control valve 41 is energized for a short time after the cam member 11 rotates to the second ramp-up step 1b of the first driving projection 111 and before the main exhaust lift, for example, between 45 and 60 CrA ATDC, so that the valve lift is generated around 90 to 100 CrA ATDC. The first control valve 41 is de-energized between 300 and 330 CrA ATDC, and the exhaust unit 32 pushes the oil in the valve return braking units 31, 31' back to the energy storage assembly 2, thereby returning the valve stem to the valve body. The de-energization time can be calibrated so that the exhaust unit 32 closes after gas exchange at 360 CrA TDC (for example, around 405 CrA ATDC).

[0055] Please refer to Figure 6 As shown, it is the single-valve movement in the compression release braking or early exhaust opening / closing stage. At this time, the first control valve 41 is in the energized state, and the third control valve 43 is also in the energized state. Therefore, the ramp-up phase on the cam member 11 is transmitted to the single-valve piston 331, and the single-valve piston 331 only pushes the exhaust unit 32 downward to open the cylinder exhaust passage; during this process, the braking unit 31', the mechanical valve bridge 332 remain in the reference position without moving. That is, the third control valve 43 can control the second control valve 42 to transmit the movement of the cam member 11 to the single-valve piston 331, thereby only driving the valve stem of one exhaust unit, so that the corresponding cylinder works in the single-valve drive mode.

[0056] The braking unit may include a piston unit. The single-valve piston 331 can interact with the piston of the piston unit of one braking unit 31, and the piston of the piston unit of the other braking unit 31' is connected to the mechanical valve bridge 332. The single-valve piston 331 is movably connected to the mechanical valve bridge 332, so that the single-valve piston 331 can move relative to the mechanical valve bridge 332 (for example, Figure 6 move downward therein) to drive the valve stem movement of one exhaust unit, so that the corresponding cylinder works in the single-valve drive mode. When the mechanical valve bridge 332 moves, it can drive the valve stem movements of two exhaust units at the same time, so that the corresponding cylinder works in the double-valve drive mode.

[0057] The second control valve 42 can make the following by switching the liquid path connection state:

[0058] For example, refer to Figure 6 , the movement of the cam member 11 causes the oil in the oil pumping chamber 123 to enter the piston unit of one braking unit 31, thereby driving the valve stem movement of one exhaust unit via the single-valve piston 331, and the mechanical valve bridge 332 does not move, so that the corresponding cylinder works in the single-valve drive mode; or, for example, refer to Figure 4, the movement of the cam member 11 causes the oil in the oil pumping chamber 123 to enter the piston unit of another braking unit 31', thereby driving the movement of the mechanical valve bridge 332. The mechanical valve bridge 332 drives the valve stems of the two exhaust units to move, so that the corresponding cylinders operate in the double-valve drive mode.

[0059] Further, refer to Figure 7 and in combination with Figure 2 、 Figure 5 As shown, in the early opening (EEVO) and early closing (EEVC) function, compared with the normal exhaust lift mode, the first control valve 41 opens about 60 CrA earlier; compared with the closing time of the normal exhaust lift mode, the first control valve 41 closes about 30 crank angles earlier, so that the exhaust unit 32 closes 10 - 30 degrees earlier (EEVC). EEVO and EEVC will jointly increase the exhaust temperature and the residual gas in the engine cylinder.

[0060] Please refer to Figure 8 As shown, it is a schematic diagram of the exhaust valve stop state in the cylinder deactivation mode. At this time, the first control valve 41 is in the power-off state, and the third control valve 43 is also in the power-off state. Therefore, the movement of the cam member 11 is only transmitted to the energy storage component 2 and no longer transmitted to the braking unit 31 or the braking unit 31'. And in this state, the braking units 31, 31', the single-valve piston 331, and the mechanical valve bridge 332 all remain at the reference position without moving.

[0061] Please refer to Figure 9 and in combination with Figure 8 、 Figure 2 As shown, during the compression release braking, the first control valve 41 is energized and the solenoid valve current starts from 460 - 470 CrA ATDC to generate the braking gas recirculation (BGR) valve lift at 480 CrA ATDC. The actual valve opening moment depends on the dynamic mechanical balance among the cylinder pressure, the exhaust manifold pressure, the spring force, and the inertia of the moving mass.

[0062] As the ramp of the BGR stage descends, the single-valve piston 331 moves back to the base circle position of the cam member 11 at 600 CrA. Then, at 90 CrA BTDC in the next engine four-stroke cycle, the first ramp-up step 1a of the first drive projection 111 of the compression release cam member 11 starts and pushes the single-valve piston 331 to open against the extremely high cylinder pressure (e.g., >60 barA). The valve remains open until the ramp-up stage of the third ramp-up step 1c of the first drive projection 111 ends, and then starts to retract with the ramp-down step 1d.

[0063] Then the current of the first control valve 41 is cut off at 310 - 315 CrA ATDC, earlier than the main exhaust lift (Figure 5) or the early closing (Figure 7 ), the exhaust valve moves back to the reference position and closes at 390 - 400 CrA ATDC. Compared with the main exhaust lift or early closing, it is necessary to turn off the current earlier to prevent oil and gas cavitation when the valve returns to the seat.

[0064] In summary, the continuously variable hydraulic valve mechanism for heavy-duty engines of the present invention is achieved by providing a cam member 11 with a unique cam profile; combining the cam member 11 with the control assembly 4 enables the continuously variable hydraulic valve mechanism to switch between single-valve and dual-valve drive; meanwhile, by providing a plurality of valve members located at different positions in the control assembly 4, the main exhaust lift or cylinder deactivation of the dual-valve, as well as the compression release braking and early opening and closing of the exhaust valve of the single-valve, are further realized.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive, characterized in that, Comprising a hydraulic circuit (5) and a continuously variable hydraulic valve mechanism, the continuously variable hydraulic valve mechanism being provided corresponding to each cylinder in a heavy-duty engine and comprising: A piston assembly (1), comprising a pump unit (12) and a cam member (11) drivingly connected to the pump unit; An energy storage assembly (2); A valve return braking assembly (3), comprising paired braking units, two exhaust units (32, 32') provided corresponding to the braking units, and a mechanical valve bridge assembly (33) provided between the braking unit and the exhaust unit; A control assembly (4), comprising a first control valve (41) provided between the energy storage assembly (2) and the piston assembly (1); a second control valve (42) provided at one end of the valve return braking assembly (3), and a third control valve (43) provided between the hydraulic circuit (5) and the continuously variable hydraulic valve mechanism; The mechanical valve bridge assembly (33) comprises a single-valve piston (331) connected in any one of the braking units and a mechanical valve bridge (332) connected in the other braking unit. The third control valve (43) can control the second control valve (42) to transfer the movement of the cam member (11) to the single-valve piston (331), thereby only driving the valve stem of one exhaust unit, so that the corresponding cylinder operates in a single-valve drive mode; the third control valve (43) can also control the second control valve (42) to transfer the movement of the cam member (11) to the mechanical valve bridge (332), thereby driving the valve stems of two exhaust units, so that the corresponding cylinder operates in a double-valve drive mode.

2. The heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive according to claim 1, characterized in that, The pump unit (12) comprises a pump roller (121) abuttedly connected to the cam member (11), a pump piston (122) connected to one end of the pump roller, a pump oil chamber (123) for accommodating the pump piston, and a pump spring (124) sleeved on the outer periphery of the pump piston.

3. The heavy-duty engine with a cylinder capable of switching between single-valve drive and dual-valve drive according to claim 1, characterized in that, The outer peripheral edge of the cam member (11) is formed with a first driving protrusion and a second driving protrusion arranged at intervals. The first driving protrusion has 3 continuous ramp-up steps and 1 ramp-down step, and the 3 ramp-up steps and the 1 ramp-down step together cover a crank angle of 470 degrees.

4. The heavy-duty engine with a cylinder capable of switching between single-valve drive and dual-valve drive according to claim 3, characterized in that, The second driving protrusion is located between the crank angles of 480 to 600 degrees on the outer periphery of the cam member for braking gas recirculation.

5. The heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive according to claim 2, characterized in that, The energy storage assembly (2) is connected to the first control valve (41) through an intermediate pressure chamber or a first passage (21); the energy storage assembly (2) comprises an accumulator oil chamber (22), an accumulator piston (23) movably connected in the accumulator oil chamber (22), and an accumulator spring (24) sleeved on the outer periphery of the accumulator piston (23). The accumulator spring (24) acts on the accumulator piston (23) and tends to make the oil in the accumulator oil chamber (22) flow to the intermediate pressure chamber or the first passage (21).

6. The heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive according to claim 5, characterized in that, The first control valve (41) can control the connection or disconnection between the pump oil chamber (123) and the accumulator oil chamber (22).

7. The heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive according to claim 1, characterized in that The first control valve is a normally open 2 / 2 solenoid valve; the second control valve is a 3 / 2-way mechanical valve; the third control valve is a pilot-operated 3 / 2-way solenoid valve.

8. The heavy-duty engine with a cylinder capable of switching between single-valve drive and double-valve drive according to claim 2, characterized in that, The braking unit includes a piston unit. The single-valve piston (331) can interact with the piston of the piston unit of a braking unit (31). The piston of the piston unit of another braking unit (31') is connected to the mechanical valve bridge (332). The single-valve piston (331) is movably connected to the mechanical valve bridge (332), so that the single-valve piston (331) can move relative to the mechanical valve bridge (332) to drive the valve stem of an exhaust unit to move. When the mechanical valve bridge (332) moves, it can drive the valve stems of two exhaust units to move simultaneously.

9. The heavy-duty engine with a cylinder capable of switching between single-valve drive and dual-valve drive according to claim 8, characterized in that, By switching the connection state of the hydraulic circuit, the second control valve can cause the following:[[]]END]] The movement of the cam member (11) causes the oil in the pump oil chamber (123) to enter the piston unit of one braking unit, thereby driving the valve stem of an exhaust unit to move via the single-valve piston (331), and the mechanical valve bridge (332) does not move; or The movement of the cam member (11) causes the oil in the pump oil chamber (123) to enter the piston unit of the other braking unit, thereby driving the mechanical valve bridge (332) to move, and the mechanical valve bridge (332) drives the valve stems of two exhaust units to move.

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