CN104712397B

CN104712397B - Composite rocker arm engine braking device

Info

Publication number: CN104712397B
Application number: CN201510097866.3A
Authority: CN
Inventors: 朱汝杰; 杨洲; 奚勇
Original assignee: Shanghai Universoon Auto Parts Co Ltd
Current assignee: Shanghai Youshun Automobile Technology Co.,Ltd.
Priority date: 2015-03-05
Filing date: 2015-03-05
Publication date: 2020-08-25
Anticipated expiration: 2035-03-05
Also published as: CN104712397A

Abstract

A composite rocker arm engine braking device is characterized in that the axial position of a rocker arm on a rocker arm shaft is changed, a cam roller on the rocker arm is switched from being connected with a conventional ignition cam to being connected with an engine braking cam, the valve motion of conventional ignition is eliminated, and the valve motion of engine braking is generated. The engine braking device of the invention obtains valve motion and high-power braking generated by a special braking cam which has no relation with an ignition cam, the special braking cam can only comprise a braking exhaust cam, and can also simultaneously have the braking exhaust cam and a braking intake cam, all engine braking operations are non-hydraulic mechanical bearing, and a failure mode of hydraulic bearing is not available. The invention has the advantages of simple and clear brake control, simple and compact structure and excellent brake performance.

Description

Composite rocker arm engine braking device

Technical Field

The invention relates to the field of machinery, in particular to the field of engine braking, and particularly relates to a composite rocker arm engine braking device.

Background

In the prior art, engine braking is well known and requires only the temporary conversion of the engine generating power into an air compressor absorbing energy. The fuel is cut off during the transition, the valve is opened near the end of the compression stroke of the engine piston, allowing the compressed gas (air during braking) to be released, and the energy absorbed by the compressed gas during the compression stroke of the engine cannot return to the engine piston during the subsequent expansion stroke, but is dissipated through the exhaust and heat dissipation system of the engine. The net result is effective engine braking, slowing the vehicle.

One precedent of an engine braking device is disclosed in U.S. patent No. 3220392 to Cummins (Cummins), the invention of which utilizes hydraulic transmission to transfer the motion of an injection cam or an adjacent exhaust cam to the valves of an engine to increase the valve motion for compression release braking over the conventional valve motion of the engine. The invention only generates one compression release brake in each period of the four strokes of the engine.

US patent 4,572,114(1986) discloses an apparatus and method for effecting two-stroke engine braking on a four-stroke engine. Thus, engine braking occurs once every two strokes or once per rotation of the crankshaft of the engine. Theoretically, two-stroke braking with two compression releases in each cycle of the engine four-stroke would have twice the braking power of a conventional four-stroke brake. However, the invention adopts two sets of hydraulic driving systems, so the mechanism is very complex and is not practically applied.

US 5,537,976(1996) discloses another two-stroke engine braking apparatus and method, which uses cam actuation, hydraulic connections, high speed solenoid valves and electronic control to effect valve movement. Since the solenoid valve needs to be opened at least once during each cycle, there are particularly high demands on the reliability and durability of the solenoid valve. Coupled with other problems with hydraulic actuation such as control of valve seating velocity, cold start of the engine, etc., the invention has not been practical.

Still another two-stroke engine braking apparatus and method is disclosed in U.S. Pat. No. 6,293,248 (2001). In order to achieve two-stroke engine braking on a four-stroke engine, in addition to requiring four cams, four rocker arms must be employed: two exhaust rocker arms (one for braking) and two intake rocker arms (one for braking) are complicated in structure and control, and the valves of the engine are opened hydraulically.

Disclosure of Invention

The invention aims to provide a composite rocker arm engine braking device which aims to solve the technical problems of complex structure, complex control, poor reliability and durability of a hydraulically-driven opening valve and limited application of the engine braking device in the prior art and also aims to solve the technical problems of high oil pressure, high leakage and high deformation of hydraulic bearing.

The invention provides a composite rocker arm engine braking device, which comprises a cam and a valve bridge, wherein two ends of the valve bridge are respectively connected with a first valve and a second valve, the cam comprises a conventional ignition cam and an engine braking cam, the lift range of the conventional ignition cam and the lift range of the engine braking cam are different, and the phase of the conventional ignition cam and the phase of the engine braking cam are different, wherein the composite rocker arm engine braking device comprises a rocker arm, a half rocker arm, a rocker arm shaft and a rocker arm axial driving mechanism, the rocker arm is rotatably arranged on the rocker arm shaft and is provided with a first axial position and a second axial position, one end of the rocker arm is connected with the cam, the other end of the rocker arm is connected with the half rocker arm, one end of the half rocker arm is rotatably arranged on the rocker arm shaft, the other end of the half rocker arm is connected with the valve bridge, and the rocker arm axial driving mechanism is connected with the rocker arm.

Furthermore, a valve motion loss mechanism is arranged between the half rocker arm and the valve bridge, and the valve motion loss mechanism cuts off motion transmission between the half rocker arm and the valve bridge.

Further, the valve motion loss mechanism is integrated into the half rocker arm.

Furthermore, the valve motion loss mechanism is an automatic valve clearance adjusting mechanism.

Further, the first valve and the second valve are both exhaust valves, the cam is an exhaust cam, and the exhaust cam comprises an exhaust cam for conventional ignition and an exhaust cam for engine braking.

Further, the first valve and the second valve are both intake valves, the cam is an intake cam, and the intake cam comprises an intake cam for conventional ignition and an intake cam for engine braking.

Further, a single valve drive mechanism is provided between the half rocker arm and the first valve.

Compared with the prior art, the invention has positive and obvious effect. The present invention utilizes a rocker arm axial drive mechanism to switch the rocker arm between a first axial position and a second axial position on a rocker arm shaft to contact a conventional ignition cam and an engine brake cam, respectively. When the conventional ignition cam drives the rocker arm, the rocker arm drives the half rocker arm to drive the first valve and the second valve to be opened and closed through the valve bridge. When the engine braking cam drives the rocker arm, the rocker arm drives the half rocker arm to drive the first valve and the second valve to open and close through the valve bridge, wherein the action process of realizing engine braking by the first valve and the second valve is included. When the valve motion loss mechanism is started, the connection with the double valves during ignition operation can be converted into the connection with the single valve during braking operation when the valve motion loss mechanism is arranged in the valve bridge and the single valve driving mechanism is arranged between the half rocker arm and the first valve. The invention has the advantages of simple and compact structure, easy manufacture and assembly, small braking load, reliability, durability, wide application and the like. Since the brake cam is independent of the conventional ignition cam, the braking performance can be optimized. The invention adopts a fixed chain type (mechanical connection) to transmit load, and eliminates the defects or failure modes of high oil pressure, high deformation and high leakage, a hydraulic jack and the like generated by hydraulic loading of the traditional engine brake.

Drawings

Fig. 1 is a schematic view (side view) of embodiment 1 of the compound rocker arm engine brake apparatus of the present invention.

Fig. 2 is a schematic view of a rocker arm in a first axial position in embodiment 1 of the compound rocker arm engine braking device of the present invention.

Fig. 3 is a schematic view of the rocker arm in embodiment 1 of the composite rocker arm engine braking device of the present invention at a second axial position.

Fig. 4 is a schematic view of embodiment 2 of the compound rocker arm engine braking apparatus of the present invention.

Fig. 5 is a schematic view of a fluid flow control valve in embodiment 2 of the compound rocker arm engine brake apparatus of the present invention.

Detailed Description

Example 1:

fig. 1 is a schematic view (side view) of embodiment 1 of the compound rocker arm engine brake apparatus of the present invention. The valve actuator 200 (the description herein applies to both intake and exhaust valve actuators) includes cams (conventional firing cam 230 and engine braking cam 2302), rocker arms 210 and a valve bridge 400. The rocker arm 210, in addition to being rotatable on the rocker shaft 205, is also axially movable along the rocker shaft 205 (fig. 2 and 3). One end of the rocker arm 210 is connected to the cam via a cam roller 235. The lands 220 of the conventional ignition cam and the

lands

232 and 233 of the engine brake cam have different lift and phase (the brake lands may be of different number, shape and size). But located on the same camshaft 225, adjacent to each other and having substantially the same internal base circle. The other end of the rocker arm 210 is connected with a half rocker arm 212, one end of the half rocker arm 212 is rotatably arranged on the rocker shaft 205, the other end of the half rocker arm 212 is connected with a valve bridge 400 through a valve clearance adjusting mechanism (an adjusting screw 110 and a elephant foot 114), and the two ends of the valve bridge 400 are respectively connected with a first valve 301 and a second valve 302. The

valves

301 and 302 are biased against a valve seat 320 of the engine block 500 by

valve springs

311 and 312, preventing gas flow between the engine cylinder and the gas passage 600. The valve lash adjustment screw 110 of the valve lash adjustment mechanism is fastened to the half rocker arm 212 by a lock nut 105.

The rocker arm 210 also carries a linkage (here a hydraulic piston) 162, controlled by oil pressure from an oil supply passage 211 in the rocker shaft 205, to the axial drive mechanism 100. The axial drive mechanism 100 may be an auxiliary camshaft synchronized with the camshaft 225, an axial land or groove on the auxiliary camshaft, which carries the linkage (hydraulic piston) 162 to move the rocker arm 210 from a first axial position (fig. 2) associated with the conventional ignition cam 230 to a second axial position (fig. 3) associated with the engine brake cam 2302. The axial drive mechanism 100 may also be integrated into a rocker arm or other mechanism within a rocker arm shaft.

The operation of this embodiment is as follows. In the normal firing state, the rocker arm 210 is in a first axial position on the rocker shaft 205, and the rocker arm 210 is connected to the normal firing cam 230 through the cam roller 235 (fig. 2), transmitting the motion of the normal firing cam 230 to the half rocker arm 212, the valve bridge 400, and the two

valves

301 and 302 of the engine, producing the normal valve motion of the engine at the time of firing.

When it is desired to convert the normal firing operation of the engine into the braking operation of the engine, the connecting member (hydraulic piston) 162 is connected to the axial drive mechanism 100, the axial drive mechanism 100 moves the rocker arm 210 from the first axial position to the second axial position, the cam roller 235 on the rocker arm is switched from being connected to the normal firing cam 230 (fig. 2) to being connected to the engine braking cam 2302 (fig. 3), the motion of the normal firing cam 230 is lost, and the motion of the engine braking cam 2302 is transferred to the two

valves

301 and 302 through the rocker arm 210, the half rocker arm 212 and the valve bridge 400, resulting in the valve motion of the engine brake.

Example 2:

fig. 4 is a schematic view of embodiment 2 of the compound rocker arm engine braking apparatus of the present invention. This embodiment differs from embodiment 1 described above in that a valve motion loss mechanism 250, comprising a piston 160 and a flow control valve 75 (see fig. 5 for valve details), is added between the half rocker arm 212 and the valve bridge 400. Here, the valve motion loss mechanism 250 is also an automatic valve lash adjustment mechanism, and the piston 160 is slidably disposed in the piston bore 190 and connected to the rocker arm 210 via the flow control valve 75 to form a fluid column having a height 234, the height 234 of the fluid column being automatically adjusted in accordance with the lash between the cam and the valve.

The flow control valve 75 (see partial cross-sectional view of fig. 5) integrated within the half rocker arm 212 includes a one-way ball valve 165 biased upwardly by a spring 177. The ball check valve 165 is driven by a funnel-shaped piston 58, which piston 58 is biased downwardly by a spring 256. When pressurized fluid (e.g., engine lubricating oil) is provided in fluid passage 218, the oil pressure overcomes the force of spring 256, moving piston 58 upward. At the same time, the oil pressure overcomes the force of the spring 177, moving the one-way ball valve 165 downward, supplying oil to the hydraulic passage 216, and hydraulically locking the underside of the one-way ball valve 165 (including the hydraulic passage 216 and all hydraulic passages and chambers communicating therewith, such as the piston bore 190 in FIG. 4).

When it is desired to convert the normal firing operation of the engine to the braking operation of the engine, the axial drive mechanism 100 moves the rocker arm 210 from the first axial position to the second axial position via the linkage (hydraulic piston 162), the rocker arm cam roller 235 switches from being connected to the normal firing cam 230 (fig. 2) to being connected to the engine braking cam 2302 (fig. 3), and the motion of the normal firing cam 230 is lost. At the same time, the fluid passage 218 leading to the flow control valve 75 is drained, the piston 58 is moved downward by the spring 256 (see FIG. 5), pushing the one-way ball valve 165 off the valve seat, allowing the hydraulic gallery 216 and the piston bore 190 communicating therewith to drain, and the fluid column above the piston 160 becomes a void 234 (see FIG. 2), such that the motion of the brake cams (bosses 232 and 233) is lost at the elephant foot 114 and cannot be transmitted to the

valves

301 and 302 through the valve bridge 400. However, since a single valve actuation mechanism is provided between the half rocker arm 212 and the first valve 301, the motion of the brake cam 2302 is transferred to the first valve 301 of the two valves of the engine through the connection of the half rocker arm 212 at 112 to the brake link 116 in the valve bridge 400, creating a valve motion for engine braking. The single valve drive mechanism herein may also include various mechanisms such as a valve lash adjustment mechanism and a motion loss mechanism. Even simple mechanical contact, may include a foot-like or other wear-resistant connection.

A snap ring 176 (or other stop mechanism) disposed within the piston bore 190 limits the travel of the piston 160 and prevents it from falling out of the piston bore 190 (facilitating handling and assembly). To prevent the flying off of the moving parts due to the clearance 234 created by the valve motion loss mechanism, anti-flying off springs or

elastic elements

117, 118 and 198 are added. The shape, type and placement and location of these resilient elements can be varied to ensure that moving parts in the device, such as the valve bridge 400, do not fly off. The height of the clearance 234 is determined by the height of the detent boss on the detent cam, which serves to absorb (lose) the motion of the detent cam from being transmitted to the valve through the valve bridge.

The above description contains different embodiments, which should not be taken as limiting the scope of the invention, but rather as representing some specific exemplifications of the invention, from which many other variations are possible. For example, the engine braking apparatus or method shown herein may be used not only in overhead cam engines, but also in push rod/push tube engines; and can be used for driving an exhaust valve and an intake valve.

In addition, the axial driving mechanism may be not only a mechanical cam mechanism, but also other mechanisms, such as hydraulic, pneumatic, electromagnetic, etc., and combinations thereof; not only integrated within the valve actuator (e.g., rocker arm), but may also be located external to the valve actuator (e.g., fixed to the engine or other moving part of the engine).

Also, the valve motion loss mechanism, the design of the brake oil passage, and the structure and arrangement of the fluid flow control valve, etc., may be different here.

The scope of the invention should, therefore, be determined not with reference to the above detailed description, but instead should be determined with reference to the appended claims along with their legal equivalents.

Claims

1. A compound rocker arm engine brake device, the engine includes the cam and the valve bridge, the both ends of the valve bridge connect with a first valve and a second valve respectively, the cam includes the conventional ignition cam and the engine brake cam, there is difference between the lift range of the conventional ignition cam and the lift range of the engine brake cam, there is difference between the phase place of the conventional ignition cam and the phase place of the engine brake cam, characterized by that: the composite rocker arm engine braking device comprises a rocker arm, a half rocker arm, a rocker arm shaft and a rocker arm axial driving mechanism, wherein the rocker arm is rotatably arranged on the rocker arm shaft and is provided with a first axial position and a second axial position, one end of the rocker arm is connected with a cam, the other end of the rocker arm is connected with the half rocker arm, one end of the half rocker arm is rotatably arranged on the rocker arm shaft, the other end of the half rocker arm is connected with the valve bridge, and the rocker arm axial driving mechanism is connected with the rocker arm.

2. The compound rocker arm engine braking device of claim 1, wherein: and a valve motion loss mechanism is also arranged between the half rocker arm and the valve bridge and cuts off motion transmission between the half rocker arm and the valve bridge.

3. The compound rocker arm engine braking device of claim 2, wherein: the valve motion loss mechanism is integrated into the half rocker arm.

4. The compound rocker arm engine braking device of claim 2, wherein: the valve motion loss mechanism is an automatic valve clearance adjusting mechanism.

5. The compound rocker arm engine braking device of claim 1, wherein: the first valve and the second valve are exhaust valves, the cam is an exhaust cam, and the exhaust cam comprises an exhaust cam for conventional ignition and an exhaust cam for engine braking.

6. The compound rocker arm engine braking device of claim 1, wherein: the first valve and the second valve are both intake valves, the cam is an intake cam, and the intake cam comprises an intake cam for conventional ignition and an intake cam for engine braking.

7. The compound rocker arm engine braking device of claim 1, wherein: a single valve drive mechanism is provided between the half rocker arm and the first valve.