CN111535893B - In-cylinder braking system of engine and hydraulic tappet matched with same - Google Patents
In-cylinder braking system of engine and hydraulic tappet matched with same Download PDFInfo
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- CN111535893B CN111535893B CN202010549287.9A CN202010549287A CN111535893B CN 111535893 B CN111535893 B CN 111535893B CN 202010549287 A CN202010549287 A CN 202010549287A CN 111535893 B CN111535893 B CN 111535893B
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- pressure relief
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- 239000003921 oil Substances 0.000 claims abstract description 202
- 239000010705 motor oil Substances 0.000 claims abstract description 52
- 238000007906 compression Methods 0.000 claims abstract description 29
- 230000006835 compression Effects 0.000 claims abstract description 28
- 238000004891 communication Methods 0.000 claims abstract description 11
- 238000007789 sealing Methods 0.000 claims description 32
- 230000009471 action Effects 0.000 claims description 14
- 230000002093 peripheral effect Effects 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 4
- 230000006837 decompression Effects 0.000 abstract description 7
- 230000008901 benefit Effects 0.000 abstract description 4
- 230000005540 biological transmission Effects 0.000 description 13
- 238000005086 pumping Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 8
- 230000007246 mechanism Effects 0.000 description 5
- 238000010276 construction Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 238000004904 shortening Methods 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000001174 ascending effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/20—Adjusting or compensating clearance
- F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
- F01L1/24—Adjusting or compensating clearance automatically, e.g. mechanically by fluid means, e.g. hydraulically
- F01L1/245—Hydraulic tappets
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
- F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
- F01L9/10—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic
- F01L9/11—Valve-gear or valve arrangements actuated non-mechanically by fluid means, e.g. hydraulic in which the action of a cam is being transmitted to a valve by a liquid column
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D13/00—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing
- F02D13/02—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation
- F02D13/04—Controlling the engine output power by varying inlet or exhaust valve operating characteristics, e.g. timing during engine operation using engine as brake
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2810/00—Arrangements solving specific problems in relation with valve gears
- F01L2810/03—Reducing vibration
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L2810/00—Arrangements solving specific problems in relation with valve gears
- F01L2810/04—Reducing noise
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Valve Device For Special Equipments (AREA)
Abstract
The invention discloses a compression release type engine in-cylinder braking system and a hydraulic tappet matched with the compression release type engine in-cylinder braking system. The control oil port of the hydraulic control switch valve is connected with an oil supply circuit of the in-cylinder braking system, when the oil supply circuit is communicated with an engine oil circuit, the hydraulic control switch valve closes the communication between the hydraulic tappet and an external oil circuit, and when the oil supply circuit is communicated with a decompression circuit, the hydraulic control switch valve is communicated with the communication between the hydraulic tappet and the external oil circuit. The in-cylinder braking system is matched with the hydraulic tappet for use, so that the engine can not only exert the special length of in-cylinder braking, but also has the advantage of eliminating noise and impact caused by a valve clearance due to the hydraulic tappet.
Description
Technical Field
The invention relates to the technical field of in-cylinder braking of engines, in particular to a compression release type in-cylinder braking system of an engine, and also relates to a hydraulic tappet in an engine valve mechanism.
Background
In the valve train of the engine, the hydraulic tappet can be arranged on any transmission part between the cam and the valve, is used for transmitting the thrust of the cam shaft to the push rod (or the valve rod) and bearing the lateral force applied when the cam shaft rotates, and can automatically compensate the valve clearance, cancel the related parts for adjusting the valve clearance and eliminate noise and impact caused by the valve clearance relative to the mechanical tappet.
Among the in-cylinder engine braking technologies, the compression release type braking technology is the technology with the best engine braking performance at present, and the basic principle is as follows: when the engine is towed backward, the piston compresses gas in the cylinder in the process of ascending the compression stroke piston, and braking power is generated. Before compression top dead center, the compression release type braking device drives the exhaust valve to open a certain opening degree, the compressed high-temperature high-pressure charge in the cylinder is discharged, at the moment, the pressure in the cylinder is rapidly reduced, after a certain crank angle is passed, the exhaust valve is closed again, the piston moves downwards, the work of the charge in the cylinder on the piston is greatly reduced because the charge in the cylinder is greatly reduced, and the reverse braking power of the charge in the cylinder on the piston is reduced or eliminated.
Chinese patent application CN111197510a discloses an in-cylinder brake system for an engine, which includes an oil cylinder device, an oil pumping device and an oil supply device applied to a valve train of the engine, all cylinders of the engine share one oil supply device; the oil supply device comprises an electromagnetic reversing valve, an oil supply oil way, a decompression oil way and a decompression oil way, wherein the engine oil pressure of the engine before decompression is P1, and the engine oil pressure of the engine after decompression is P2; each cylinder of the engine is respectively provided with an oil cylinder device and an oil pumping device, the oil cylinder device is communicated with the oil pumping device through a pressure transmission oil way, the pressure transmission oil way is communicated with an oil supply oil way through a low-pressure relief valve, and a bleed valve is arranged at the high end of the oil way system; when in-cylinder braking, the air release valve is closed, the electromagnetic reversing valve is electrified, engine oil with the pressure of P1 is provided for the pressure transmission oil way through the oil supply oil way, and the piston of the oil cylinder device and the plunger of the oil pumping device extend out; when the cam is propped against and pushes the oil pumping device, the oil pressure in the oil pumping device is increased, the oil pumping device pumps high-pressure oil with the pressure P to the oil cylinder device through the pressure transmission oil way, the low-pressure relief valve is closed, and the oil cylinder device pushes the rocker arm to open the valve, so that in-cylinder braking is realized; when the non-in-cylinder brake is carried out, the air release valve is opened, the electromagnetic directional valve is powered off, engine oil with the pressure of P2 is supplied to the pressure transmission oil way through the oil supply oil way, at the moment of power failure of the electromagnetic directional valve, the low-pressure relief valve is in an open state, the oil pressure in the pressure transmission oil way is relieved through the low-pressure relief valve and is reduced to P2, the oil cylinder device and the oil pumping device return respectively, the cam is separated from the oil pumping device, the engine is in a normal running state, the engine oil or air in the pressure transmission oil way is continuously discharged through the air release valve, and the problem that the power transmission effect is seriously influenced by entering air in the pressure transmission oil way when the engine is in a stop state is solved. Because each cylinder of the engine is respectively provided with the oil cylinder device and the oil pumping device which are connected through the pressure transmission oil way, the pressure transmission oil way is communicated with the oil supply oil way of the oil supply device through the low-pressure relief valve, and only the on/off of the electromagnetic reversing valve is controlled, the braking/non-braking conversion of all cylinders of the whole engine can be realized, the requirement on a control circuit is low, the operation is stable and reliable, and the failure rate is low; in addition, the structure is simple, the arrangement is flexible and convenient, the engine cylinder number is not limited, even number and odd number can be realized, the application performance is good, and the application is wider.
When the above-mentioned in-cylinder brake system is applied to a dual-valve train, as shown in fig. 1, a rocker arm drives two valves (two intake valves or two exhaust valves) simultaneously through a valve bridge, but when an engine is braked in a cylinder, the in-cylinder brake mechanism drives one valve to open alone, and if a conventional hydraulic tappet is disposed on the valve train, for example, the hydraulic tappet disclosed in the chinese patent application No. cn202010460474.X, there are the following problems:
when the in-cylinder braking state is achieved, one valve is driven to be opened by the in-cylinder braking mechanism, the valve bridge moves downwards, the rocker arm does not move relatively, the hydraulic tappet stretches at the moment and automatically compensates a gap formed by the descending of the valve bridge, when the in-cylinder braking is finished, the valve is closed, and at the moment, the valve cannot be completely closed due to the fact that the hydraulic tappet is not shortened, so that the valve cannot be sealed in the subsequent working process, compressed gas in the cylinder leaks, and the in-cylinder braking effect is reduced or even fails.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention provides a hydraulic tappet suitable for in-cylinder braking, and as a same concept, the present invention also provides a compression release type in-cylinder braking system of an engine, where the in-cylinder braking system can be used in combination with the hydraulic tappet, so that the engine can not only exert the characteristics of in-cylinder braking, but also has the advantages of eliminating noise and impact caused by valve clearance brought by the hydraulic tappet.
In order to solve the first technical problem, the invention adopts the following technical scheme:
A hydraulic lifter, comprising: the hydraulic tappet comprises a tappet body and a plunger, wherein one end of the tappet body is provided with an oil inlet, the other end of the tappet body is open, the plunger extends into the tappet body from the open end of the tappet body and forms a hydraulic cavity with the tappet body, and a one-way valve capable of communicating an external oil way with the hydraulic cavity under the action of engine oil pressure is arranged at the inner side of the oil inlet; the outer peripheral surface of the plunger is in sliding sealing fit with the inner peripheral surface of the tappet body; the plunger is provided with a pressure relief channel communicated with the hydraulic cavity, the pressure relief channel is provided with a sealing conical surface, a pressure relief valve core and a pressure relief spring are arranged in the pressure relief channel, the pressure relief valve core is propped away from the sealing conical surface by the pressure relief spring to form an oil leakage gap when the pressure relief valve core is not acted by the opening pressure of the valve, and the pressure relief valve core overcomes the elasticity of the pressure relief spring and contacts with the sealing conical surface to realize the sealing of the hydraulic cavity when the pressure relief valve is acted by the opening pressure of the valve; the pressure relief valve seat is fixedly arranged on the plunger in the hydraulic cavity and is positioned above the pressure relief valve core, the pressure relief valve seat is provided with a through hole, and the through hole is communicated with the hydraulic cavity and the pressure relief channel; the hydraulic tappet is provided with an elastic device which enables the plunger to be in a retraction state after the oil pressure in the hydraulic cavity is eliminated.
The elastic device comprises an extension spring arranged between the pressure relief valve seat and the one-way valve, and the extension spring is arranged in the hydraulic cavity.
The one-way valve comprises a one-way valve core, a limiting spring and a one-way valve seat, wherein a sealing conical surface is arranged on the inner side of the oil inlet, the limiting spring is arranged in the one-way valve seat, the one-way valve seat is fixedly arranged on a tappet body of the hydraulic cavity, the limiting spring props against the one-way valve core to the sealing conical surface of the oil inlet, and one end of the stretching spring is fixedly connected with the other end of the one-way valve seat and is fixedly connected with the pressure relief valve seat.
The elastic device comprises an extension spring connected between the tappet body and the plunger, and the extension spring is arranged outside the hydraulic cavity.
The elastic device comprises a compression spring, one end of the compression spring is propped against the extending end of the plunger, the other end of the compression spring is propped against a component capable of generating relative displacement with the plunger, and the compression spring is arranged outside the hydraulic cavity.
In order to solve the second technical problem, the invention adopts the following technical scheme:
The compression release type engine in-cylinder braking system comprises an oil supply device connected with an engine oil circuit, wherein the oil supply device comprises an electromagnetic reversing valve, an oil supply circuit and a pressure reducing circuit, the pressure reducing circuit is connected with a pressure reducing circuit, an overflow pressure maintaining valve is arranged in the pressure reducing circuit, and the oil supply circuit is selectively communicated with the engine oil circuit and the pressure reducing circuit through the electromagnetic reversing valve; the hydraulic tappet comprises an engine oil path, an oil supply path, a hydraulic control switch valve, an oil inlet of the hydraulic control switch valve, an oil outlet of the hydraulic control switch valve, an oil inlet of a tappet body of the hydraulic tappet, and a hydraulic control switch valve.
The hydraulic control switch valve comprises a valve body, wherein the valve body is provided with a control oil port, an oil outlet and an oil inlet respectively, a valve core and a return spring are arranged in the valve body and are fixed by a valve cover in a sealing manner, and the valve core is provided with a communication oil path for communicating the oil inlet and the oil outlet.
After the technical scheme is adopted, the technical effects achieved by the invention are as follows:
The invention relates to an in-cylinder braking system of an engine, which is a system for realizing braking by adopting control engine oil.
When the engine works in a non-in-cylinder braking mode, the electromagnetic directional valve of the oil supply device is powered off, the oil supply oil way is communicated with the low-pressure oil way through the electromagnetic directional valve, at the moment, the hydraulic control switch valve is communicated with the hydraulic tappet and the external oil way, if the cam does not work, the hydraulic plunger is not affected by the opening pressure of the valve, the pressure release valve core is propped away from the sealing conical surface of the pressure release channel by the pressure release spring, engine oil enters the hydraulic cavity through the oil inlet and the one-way valve, and meanwhile, the engine oil slowly leaks through the gap between the pressure release valve core and the sealing conical surface, at the moment, the tappet body and the plunger are respectively (directly or indirectly) close to the cam and the valve under the action of the engine oil pressure, and the valve gap is eliminated; if the cam works, the engine oil pressure of the hydraulic cavity is increased, the pressure relief valve core overcomes the elasticity of the pressure relief spring, the hydraulic cavity becomes a closed cavity, no matter how the rotation speed of the engine changes, the relative position of the tappet body and the plunger cannot change, and the performance of the engine is ensured. Because the oil leakage gap can be formed between the pressure release valve core and the sealing conical surface, when the cam does not work, engine oil of the engine can enter the hydraulic cavity through the oil inlet and the one-way valve and slowly leak through the oil leakage gap, the working length of the hydraulic tappet can be prolonged, the working length of the hydraulic tappet can be shortened, and the thermal expansion gap of a valve actuating mechanism part can be automatically compensated. When the cam works, the oil leakage gap is closed, the working length of the hydraulic tappet is hardly changed (only slightly shortened in the initial stage of the cam work, and the shortening amount is controllable), so that the valve opening stroke is more accurate.
When the engine is in the in-cylinder braking mode, the electromagnetic directional valve is electrified, the oil supply oil way is communicated with an engine oil way (high-pressure oil way) through the electromagnetic directional valve, under the action of high-pressure oil, the hydraulic control switch valve is closed, the hydraulic tappet is connected with an external oil way, and under the action of the elastic device, the hydraulic tappet is not stretched any more, the valve clearance is not automatically compensated, and the braking effect is not influenced. The in-cylinder braking system of the engine is matched with the hydraulic tappet for use, so that the engine can not only exert the characteristic of in-cylinder braking, but also have the advantage of eliminating noise and impact caused by valve clearance due to the hydraulic tappet.
The hydraulic tappet of the invention can also be matched with other in-cylinder braking systems in other structural forms, and at the moment, the on/off mode of engine oil can be realized by adopting an electromagnetic switch valve or other modes. When in a non-in-cylinder braking state, engine oil is communicated with the hydraulic cavity, the pressure of the engine oil overcomes the elasticity of the elastic device, and the hydraulic tappet stretches and has the same working principle as the traditional hydraulic tappet. When the brake is in the cylinder, the engine oil way is disconnected, the hydraulic tappet is shortened under the elastic action of the elastic device, and the valve clearance is not compensated automatically. In the in-cylinder braking state, the hydraulic tappet can not extend any more (the shortening amount can be ensured by mechanical limiting and cannot be too short) as long as the connection between an engine oil way and an oil inlet hole of the hydraulic tappet is controlled to be disconnected, so that the braking effect is ensured.
Drawings
FIG. 1 is a schematic illustration of a known dual valve train configuration;
FIG. 2 is a cross-sectional view of a first construction of the hydraulic lifter of the present invention;
FIG. 3 is a cross-sectional view of a second construction of the hydraulic lifter of the present invention;
FIG. 4 is a cross-sectional view of a third construction of the hydraulic lifter of the present invention;
FIG. 5 is a schematic diagram of the principle construction of an embodiment of the compression release engine in-cylinder braking system of the present invention for use with a hydraulic lifter;
In the figure:
10-cams, 20-push rods, 30-rocker arms, 40-hydraulic lifters, 50-valve springs, 60-valves, 61-valve bridges, 70-orifices, 80-electromagnetic directional valves, 90-one-way valves, 100-overflow pressure-maintaining valves, 120-oil pans and F-in-cylinder braking force application directions;
L0-engine oil circuit, la-oil supply circuit, lb-pressure relief circuit and Lc-pressure relief circuit;
40B-hydraulic tappet, 41B-plunger, 411B-oil drain hole, 42B-tappet body, 421B-oil inlet, 43B-hydraulic cavity, 44B-check valve, 441B-check valve seat, 442B-check valve core, 443B-limit spring, 45B 1-extension spring, 45B 2-extension spring, 45B 3-compression spring, 46B-sealing conical surface, 47B-pressure relief valve core, 48B-pressure relief spring, 49B-pressure relief valve seat and 491B-through hole;
110-hydraulic control switching valve, 1101-valve body, 1102-control oil port, 1103-oil outlet, 1104-oil inlet, 1105-valve core, 1106-communication oil path, 1107-return spring and 1108-valve cover.
Detailed Description
The invention will be further described with reference to the drawings and examples.
As shown in fig. 5, a compression-release type in-cylinder brake system for an engine is a system that realizes braking by using control oil. The engine oil supply device comprises an oil supply device connected with an engine oil circuit L0, wherein the oil supply device comprises an electromagnetic directional valve 80, an oil supply circuit La and a pressure reducing circuit Lb, the pressure reducing circuit Lb is connected with a pressure reducing circuit Lc, and the oil supply circuit La is selectively communicated with the engine oil circuit L0 and the pressure reducing circuit Lb through the electromagnetic directional valve 80. The electromagnetic directional valve 80 is preferably a two-position three-way electromagnetic directional valve, and a one-way valve 90 is further arranged in front of the electromagnetic directional valve 80, and the one-way valve 90 can further protect the engine oil path L0 from the impact of the high-pressure engine oil which flows back. The relief oil passage Lc is provided with an overflow pressure maintaining valve 100. For convenience of description, the oil pressure of the engine oil path L0 before decompression is defined as P1, P1 is a high pressure, the oil pressure of the engine after decompression is defined as P2, P2 is a low pressure, and the set pressure of the relief pressure maintaining valve 100 is P2 or slightly higher than P2. The more detailed structure and working principle of the engine in-cylinder brake system are disclosed in the chinese patent application CN111197510a, and will not be described here.
As shown in fig. 5, the oil supply path La is connected to the control oil port 1102 of the pilot operated switching valve 110, the oil inlet 1104 of the pilot operated switching valve 110 is connected to the engine oil path P0, the oil outlet 1103 of the pilot operated switching valve is connected to the hydraulic lifter 40B, when the oil supply path La is communicated with the engine oil path L0, under the action of the high-pressure oil P1, the pilot operated switching valve 110 closes the external oil inlet channel of the hydraulic lifter 40B, and when the oil supply path La is communicated with the pressure reducing path Lb, the pilot operated switching valve 110 opens the external oil inlet channel of the hydraulic lifter 40B.
As shown in fig. 5, the hydraulic control switch valve 110 has a specific structure that a control oil port 1102, an oil outlet 1103 and an oil inlet 1104 are respectively provided on a valve body 1101, a valve core 1105 and a return spring 1107 are provided in the valve body 1101 and fixed by a valve cover 1108, and the valve core 1105 is provided with a communication oil path 1106. Fig. 3 shows a state when the hydraulic lifter 40B is in communication with an external oil inlet passage, at this time, the system is in a non-in-cylinder braking state, the electromagnetic directional valve 80 is de-energized, the oil supply passage La is in communication with the pressure reducing passage Lb, the pressure of the oil port 1102 is controlled to be low pressure P2, the return spring 1107 pushes the spool 1105 to the left, and the communication passage 1106 is in a position in simultaneous communication with the oil inlet 1104 and the oil outlet 1103. When the system is in a braking state in a cylinder, the electromagnetic directional valve 80 is powered, the oil supply oil way La is communicated with the engine oil way L0, the pressure of the oil port 1102 is controlled to be high pressure P1, the high pressure P1 overcomes the elasticity of the return spring 1107 to push the valve core 1105 rightward, the oil inlet 1104 cannot be communicated with the oil outlet 1103 through the communication oil way 1106, and therefore the connection between the engine oil way L0 and the hydraulic tappet oil way is cut off.
Fig. 2 shows a first specific structure of the hydraulic lifter 40B. An oil inlet 421B is formed in one end of the tappet body 42B, the other end of the tappet body is open, a plunger 41B extends into the tappet body 42B from the open end of the tappet body and forms a hydraulic cavity 43B with the tappet body 42B, the oil inlet 421B is communicated with an engine oil circuit (not shown in the figure) arranged on the rocker arm 30, a check valve 44B is arranged on the inner side of the oil inlet 421B, and the check valve 44B can communicate the engine oil circuit with the hydraulic cavity 43B under the action of engine oil pressure. The check valve 44B has a specific structure that includes a check valve core 442B, a limit spring 443B and a check valve seat 441B, wherein a sealing conical surface is provided at the inner side of the oil inlet 421B, the limit spring 443B is disposed in the check valve seat 441B, the check valve seat 441B is provided with an oil through hole and is fixedly mounted on a tappet body 42B of the hydraulic cavity, and the limit spring 443B pushes the check valve core 442B against the sealing conical surface of the oil inlet 421. The unidirectional valve core 442B is preferably a valve ball, such as a steel ball.
The plunger 41B in the hydraulic cavity 43B is fixedly provided with a pressure relief valve seat 49B, the pressure relief valve seat 49B is positioned above the pressure relief valve core 47B, the pressure relief valve seat 49B is provided with a through hole, the through hole is communicated with the hydraulic cavity 43B and the pressure relief channel 411B, and an extension spring 45B1 which enables the plunger 41B to be in a retracted state after the oil pressure in the hydraulic cavity 43B is eliminated is arranged between the pressure relief valve seat 49B and the one-way valve 44B. In the in-cylinder braking state, when the engine oil pressure is cut off, the plunger 41B may not be extended by the tension of the extension spring 45B1, and the closing of the valve is not affected after the in-cylinder braking is completed, so that the braking effect is not affected. In this embodiment, one end of the extension spring 45B is fixedly connected to the one-way valve seat 441B, and the other end is fixedly connected to the pressure release valve seat 49B.
The outer peripheral surface of the plunger 41B is slidably fitted to the inner peripheral surface of the tappet body 42B, and the fit clearance thereof ensures smooth sliding and sealing of the plunger, from which oil must not leak. The plunger 41B is provided with a pressure release passage 411B communicating with the hydraulic chamber 43B, and the pressure release passage 411B communicates with the oil pan 70. The pressure release channel 411B is provided with a sealing conical surface 46B, and a pressure release valve core 47B and a pressure release spring 48B are arranged in the pressure release channel 411B, and preferably, the pressure release valve core 47B comprises a valve ball, such as a steel ball. The elastic force of the pressure release spring 48B should ensure that when the engine oil reaches the highest value, the pressure release valve core 47B still can be separated from the sealing conical surface 46B to form an oil leakage gap, and when the cam working hydraulic chamber 43B forms high pressure, the pressure release valve core 47B can rapidly seal the sealing conical surface 46B. The pressure release spring 48B is disposed in the pressure release channel 411B communicating with the small end of the sealing conical surface 46B, and abuts against between the pressure release valve core 47B and one of the stepped surfaces of the pressure release channel. When the valve opening pressure is not acted, the pressure release valve core 47B is propped against the sealing conical surface 46B by the pressure release spring 48B; when the valve opening pressure is applied, the relief valve core 47B overcomes the elastic force of the relief spring 48B and contacts the sealing conical surface 46B to seal the hydraulic chamber 43B.
The invention combines the working principle, and the technical effects obtained by the invention are as follows:
When the engine works in a non-in-cylinder braking mode, the electromagnetic directional valve 80 of the oil supply device is powered off, the oil supply oil way La is communicated with the low-pressure oil way Lb through the electromagnetic directional valve 80, at the moment, the hydraulic control switch valve 110 opens the connection between the hydraulic tappet 40B and an external oil way, if the cam 10 does not work, the hydraulic tappet 40B is not acted by the opening pressure of a valve, the pressure release valve core 47B is propped away from the sealing conical surface 46B of the pressure release channel by the pressure release spring 48B, engine oil enters the hydraulic cavity 43B through the oil inlet 421B and the one-way valve 44B, and meanwhile, the engine oil slowly leaks through the gap between the pressure release valve core 47B and the sealing conical surface 46B, at the moment, the hydraulic tappet body 42B and the plunger 41B are respectively (directly or indirectly) clung to the cam 10 and the valve 60 under the action of the engine oil pressure, and the valve gap is eliminated; if the cam works, the oil pressure of the hydraulic cavity rises, the pressure relief valve core 47B overcomes the elasticity of the pressure relief spring 48B, the hydraulic cavity 43B becomes a closed cavity, the relative position of the tappet body 42B and the plunger 41B cannot be changed no matter how the rotation speed of the engine changes, and the performance of the engine is ensured. Because the oil leakage gap can be formed between the pressure release valve core 47B and the sealing conical surface 46B, when the cam does not work, engine oil of the engine can enter the hydraulic cavity 43B through the oil inlet and the one-way valve and slowly leak through the oil leakage gap, the working length of the hydraulic tappet can be prolonged, shortened and the thermal expansion gap of a valve actuating mechanism part can be automatically compensated. When the cam is operated, the oil leakage gap is closed, the operation length of the hydraulic lifter 40A is hardly changed (only slightly shortened in the initial stage of the cam operation, the amount of shortening is controllable), and thus the valve opening stroke is more "accurate".
When the engine is in the in-cylinder braking mode, the electromagnetic directional valve 80 is electrified, the oil supply oil way La is communicated with an engine oil way L0 (high-pressure oil way) through the electromagnetic directional valve 80, the hydraulic control switch valve 110 is used for closing the connection between the hydraulic tappet 40B and an external oil way under the action of high-pressure oil P1, the hydraulic tappet 40B is not stretched any more under the action of the extension spring 45B1, the valve clearance is not automatically compensated, and the braking effect is not influenced. Therefore, the in-cylinder braking system of the engine is matched with the hydraulic tappet for use, so that the engine can not only exert the special length of in-cylinder braking, but also have the advantage of eliminating noise and impact caused by valve clearance brought by the hydraulic tappet.
In the present invention, the extension spring 45B1 may be installed at another position, and as shown in fig. 3, the extension spring 45B2 is connected between the tappet body 42B and the plunger 41B and is disposed outside the hydraulic chamber 43B. It is even possible to employ a compression spring, as shown in fig. 4, in which one end of the compression spring 45B3 abuts against the projecting end of the plunger 41B, the other end abuts against a member relatively displaceable with the plunger 41B (in this embodiment, the other end of the compression spring 45B3 abuts against the valve bridge 60), and is provided outside the hydraulic chamber 43B. Whether an extension spring or a compression spring, the nature of the spring means is such that the plunger 41B is in a retracted state after the oil pressure in the hydraulic chamber 43B is eliminated.
In the present invention, the hydraulic tappet 40B may be used in combination with other in-cylinder brake systems, and at this time, the oil inlet of the tappet body 42B is to be connected to an engine oil path controlled by a switching valve, which may be a hydraulic switching valve or an electromagnetic switching valve.
In the present invention, the position of the hydraulic lifter 40B is not limited to the rocker arm, and it may be provided on any one of the transmission members between the cam and the valve of the valve train of the engine.
The present invention is not limited to the above embodiments, and all modifications based on the concept, principle, structure and method of the present invention are included in the scope of the present invention.
Claims (7)
1. A compression-release engine in-cylinder braking system comprising:
The oil supply device comprises an electromagnetic reversing valve, an oil supply oil way and a pressure relief oil way, wherein the pressure relief oil way is connected with a pressure relief oil way, an overflow pressure maintaining valve is arranged in the pressure relief oil way, and the oil supply oil way is selectively communicated with the engine oil way and the pressure relief oil way through the electromagnetic reversing valve; it is characterized in that the method comprises the steps of,
The hydraulic control valve is used for opening the hydraulic tappet and is connected with an external oil way when the oil supply way is communicated with the engine oil way;
the hydraulic tappet comprises a tappet body and a plunger, wherein one end of the tappet body is provided with an oil inlet, the other end of the tappet body is open, an oil outlet of the hydraulic control switch valve is connected with the oil inlet of the tappet body, the plunger extends into the tappet body from the open end of the tappet body and forms a hydraulic cavity with the tappet body, and a one-way valve capable of communicating an external oil way with the hydraulic cavity under the action of engine oil pressure is arranged at the inner side of the oil inlet;
the outer peripheral surface of the plunger is in sliding sealing fit with the inner peripheral surface of the tappet body;
The plunger is provided with a pressure relief channel communicated with the hydraulic cavity, the pressure relief channel is provided with a sealing conical surface, a pressure relief valve core and a pressure relief spring are arranged in the pressure relief channel, the pressure relief valve core is propped away from the sealing conical surface by the pressure relief spring to form an oil leakage gap when the pressure relief valve core is not acted by the opening pressure of the valve, and the pressure relief valve core overcomes the elasticity of the pressure relief spring and contacts with the sealing conical surface to realize the sealing of the hydraulic cavity when the pressure relief valve is acted by the opening pressure of the valve;
The pressure relief valve seat is fixedly arranged on the plunger in the hydraulic cavity and is positioned above the pressure relief valve core, the pressure relief valve seat is provided with a through hole, and the through hole is communicated with the hydraulic cavity and the pressure relief channel;
The hydraulic tappet is provided with an elastic device which enables the plunger to be in a retraction state after the oil pressure in the hydraulic cavity is eliminated;
When the engine works in a non-cylinder braking mode, the electromagnetic directional valve of the oil supply device is powered off, the oil supply oil way is communicated with the pressure reducing oil way through the electromagnetic directional valve, at the moment, the hydraulic control switch valve opens the connection between the hydraulic tappet and an external oil way, if a cam of the engine does not work, the hydraulic tappet is not acted by the opening pressure of an air valve, the pressure relief valve core is propped away from a sealing conical surface of the pressure relief channel by the pressure relief spring, engine oil enters a hydraulic cavity of the hydraulic tappet through an oil inlet of the tappet body and a one-way valve of the hydraulic tappet, and meanwhile, the engine oil slowly leaks through the oil leakage gap, and at the moment, the tappet body and the plunger are respectively clung to the cam and the air valve under the action of the engine oil pressure, so that the air valve gap is eliminated; if the cam works, the oil pressure of the hydraulic cavity rises, the pressure release valve core overcomes the elasticity of the pressure release spring, the oil leakage gap is closed, and the hydraulic cavity becomes a closed cavity;
When the engine works in a braking mode in a cylinder, the electromagnetic directional valve of the oil supply device is electrified, the oil supply oil way is communicated with the engine oil way through the electromagnetic directional valve, under the action of high-pressure oil, the hydraulic control switch valve closes the connection between the hydraulic tappet and an external oil way, and under the action of the elastic device, the hydraulic tappet is not stretched any more;
An oil inlet of the tappet body is connected with an engine oil circuit controlled by a switch valve;
The hydraulic control switch valve comprises a valve body, the valve body is respectively provided with a control oil port, an oil outlet and an oil inlet, a valve core and a return spring are arranged in the valve body and are fixed by a valve cover, and the valve core is provided with a communication oil path for communicating the oil inlet and the oil outlet.
2. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said resilient means includes an extension spring disposed between said pressure relief valve seat and said check valve, said extension spring being disposed within said hydraulic chamber.
3. The compression-release type engine in-cylinder braking system according to claim 2, wherein the check valve comprises a check valve core, a limit spring and a check valve seat, a sealing conical surface is arranged on the inner side of the oil inlet, the limit spring is arranged in the check valve seat, the check valve seat is fixedly arranged on a tappet body of the hydraulic cavity, the limit spring pushes the check valve core against the sealing conical surface of the oil inlet, and one end of the extension spring is fixedly connected with the other end of the check valve seat and is fixedly connected with the pressure relief valve seat.
4. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said resilient means includes an extension spring connected between said tappet body and said plunger, said extension spring being disposed outside said hydraulic chamber.
5. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said elastic means includes a compression spring having one end abutting against an extended end of said plunger and the other end abutting against a member relatively displaceable with said plunger, said compression spring being disposed outside said hydraulic chamber.
6. The compression-release type engine in-cylinder brake system as defined in claim 1, wherein said on-off valve is an electromagnetic on-off valve.
7. The compression-release engine in-cylinder brake system as defined in claim 1, wherein said on-off valve is a pilot-operated on-off valve.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010549287.9A CN111535893B (en) | 2020-06-16 | 2020-06-16 | In-cylinder braking system of engine and hydraulic tappet matched with same |
| PCT/CN2021/070620 WO2021253812A1 (en) | 2020-06-16 | 2021-01-07 | Engine in-cylinder braking system and hydraulic tappet matching same |
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| CN202010549287.9A CN111535893B (en) | 2020-06-16 | 2020-06-16 | In-cylinder braking system of engine and hydraulic tappet matched with same |
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| CN111535893B true CN111535893B (en) | 2024-05-07 |
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| WO (1) | WO2021253812A1 (en) |
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| CN111535893B (en) * | 2020-06-16 | 2024-05-07 | 潍坊力创电子科技有限公司 | In-cylinder braking system of engine and hydraulic tappet matched with same |
| CN112377282A (en) * | 2020-12-02 | 2021-02-19 | 博鼎汽车科技(山东)有限公司 | Hydraulic tappet and compression release type engine in-cylinder braking system |
| CN116201620B (en) * | 2023-01-31 | 2024-05-17 | 重庆长安汽车股份有限公司 | Hydraulic tappet, engine and vehicle |
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| CN111535893A (en) | 2020-08-14 |
| WO2021253812A1 (en) | 2021-12-23 |
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