A control method for engine camshaft phasing
By inserting a locating pin into the observation hole of the engine cover and using a phase adjuster to fix the fixture, combined with the synchronous rotation of the protractor and the crankshaft flywheel, the problems of low disassembly efficiency and poor accuracy in engine camshaft phase adjustment are solved, and fast and accurate phase adjustment is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- FAW QI NEW POWER (CHANGCHUN) TECHNOLOGY CO LTD
- Filing Date
- 2026-05-28
- Publication Date
- 2026-07-14
AI Technical Summary
The existing engine camshaft phase adjustment process requires the removal of the external cover, resulting in low efficiency and poor precision in quantitative angle control. Furthermore, the lack of a torque unloading structure during bolt removal and installation can easily cause phase shift.
By inserting a positioning pin into the observation hole of the upper cover and using a phase adjuster to fix the fixture, combined with the synchronous rotation of the angle gauge and the crankshaft flywheel, the rigid locking and phase adjustment of the camshaft are achieved. The bidirectional rotational abutment mechanism of the fixture is used to unload the reaction torque of the disassembly bolts.
It enables rapid and precise phase adjustment in engine assembly or bench testing environments, reducing disassembly and assembly workload and ensuring quantitative phase control and accurate fixation of the target phase.
Smart Images
Figure CN122383448A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of engine timing adjustment, and more particularly to a control method for engine camshaft phase adjustment. Background Technology
[0002] Currently, camshaft phase directly determines the timing and duration of the opening and closing of the engine's intake and exhaust valves. It is a core control parameter of the valve train. The phase setting affects the overall engine's power performance, operational reliability, emissions levels, and fuel economy. During engine assembly or bench testing, operators need to calibrate and adjust it.
[0003] To address the aforementioned valve timing calibration requirements, existing adjustment methods rely on specific mechanical positioning devices. The conventional procedure involves inserting a locating pin with an eccentric structure into the camshaft to disconnect it from the front-end phase adjuster; subsequently, the camshaft is manually rotated to a specific position and then tightened. Another approach involves mounting an external fixture with angular scale lines above the cylinder head, attaching the fixture's rotating module to the hexagonal prism surface of the camshaft, and synchronously reading the phase angle value as the camshaft rotates.
[0004] These traditional adjustment methods have specific limitations. Setting up the angle reading fixture requires the prior removal of external parts such as the engine cover; the disassembly step increases operation time and changes the engine's enclosed state, making it difficult to complete quick adjustments in situ within the assembled machine environment. The method of rotating the camshaft and maintaining its position does not provide a fixed reference locking end; the operator's observation of the scale lines has visual alignment deviations, making it difficult to achieve precise quantitative control of relative angle adjustments. Loosening or tightening the phase adjuster fixing bolts generates a reverse rotational torque; the internal transmission system is forced to bear this torque, lacking an external force unloading structure, and the stress state when the bolts are tightened can easily cause circumferential slippage of the components, resulting in a deviation from the originally intended target phase.
[0005] Therefore, the present invention provides a control method for engine camshaft phase adjustment to overcome the shortcomings of the prior art. Summary of the Invention
[0006] The purpose of this invention is to provide a control method for engine camshaft phase adjustment, which aims to solve the problems of low efficiency, poor accuracy of angle quantitative control, and phase shift caused by the need to disassemble the external cover during the existing engine camshaft phase adjustment process, as well as the lack of torque unloading structure during bolt removal and installation.
[0007] This invention provides the following solution:
[0008] This invention provides a control method for engine camshaft phase adjustment, comprising the following steps:
[0009] During the initial state confirmation and camshaft zero-position locking stage, remove the screw plug in the observation hole of the upper cover, attach the protractor to the flywheel sleeved on the crankshaft, rotate the crankshaft to rotate the U-shaped positioning groove of the camshaft to the vertical direction, screw the camshaft positioning pin into the observation hole and insert it into the U-shaped positioning groove, and record the initial angle.
[0010] During the tooling intervention and camshaft-crankshaft relative angle adjustment stage, insert the phase adjuster fixing tool into the front cover and abut against the camshaft phase adjuster. Loosen the fixing bolts with an external tightening tool, pull out the phase adjuster fixing tool, and then rotate the crankshaft to the target angle.
[0011] During the phase secondary locking and system reset recovery phase, the phase adjuster fixing fixture is inserted into the front cover again and abuts against the camshaft phase adjuster in the opposite direction. The fixing bolts are tightened, the phase adjuster fixing fixture, camshaft positioning pin and angle gauge are removed, and the screw plug is screwed back in and tightened in the observation hole.
[0012] Preferably, the specific operations of attaching the protractor to the flywheel fitted on the crankshaft and recording the initial angle include:
[0013] The protractor is attached to the outer circumference of the flywheel, and the protractor rotates synchronously in the circumference along with the flywheel and crankshaft.
[0014] After the camshaft is locked by the camshaft locating pin, the current crankshaft angle value displayed by the protractor attached to the flywheel is read and recorded, and defined as the initial angle.
[0015] Preferably, the specific operation of screwing the camshaft positioning pin into the observation hole and inserting it into the U-shaped positioning groove includes:
[0016] Align the external thread of the mounting part of the camshaft locating pin with the internal thread of the observation hole of the upper cover, and screw the mounting part completely into the observation hole by applying a tightening torque.
[0017] The cylindrical working part, which extends coaxially from the front end of the mounting part, extends into the engine along the axial direction and is inserted into the U-shaped positioning groove in the vertical direction. The outer circumferential surface of the cylindrical working part makes bidirectional rigid contact with the two parallel side walls of the U-shaped positioning groove, and the bottom end face of the working part in the axial direction directly abuts against the bottom surface of the U-shaped positioning groove.
[0018] Preferably, the specific operation of inserting the phase adjuster fixing fixture into the front cover and abutting against the camshaft phase adjuster includes:
[0019] Insert the insertion part of the phase adjuster fixing fixture axially into the through hole of the front cover;
[0020] Two protrusions extending forward from the front end of the phase adjuster fixture enter two grooves on the outer end face of the camshaft phase adjuster, with the protrusions separated from the circumferential sidewalls of the grooves and leaving a gap.
[0021] Preferably, the specific operations of contacting the camshaft phase adjuster and loosening the fixing bolts using an external tightening tool include:
[0022] Manually rotate the phase adjuster fixing fixture clockwise until the two protruding clockwise sidewalls rigidly abut and fit against the circumferential clockwise sidewalls of the corresponding two grooves.
[0023] An external tightening tool passes through a through hole at the center axis of the phase adjuster fixture and engages with the head of the fixing bolt, applying a reverse rotational torque to the fixing bolt to loosen it. The loosening reaction torque on the camshaft phase adjuster is carried by the phase adjuster fixture and transmitted to the front cover.
[0024] Preferably, the specific operation of rotating the crankshaft to the target angle includes:
[0025] A clockwise rotational driving force is applied to the crankshaft, and the rotation of the crankshaft synchronously drives the crankshaft sprocket, which is rigidly connected to the crankshaft, to rotate clockwise. The crankshaft sprocket drives the camshaft phase adjuster to rotate through the timing chain meshing with the crankshaft sprocket.
[0026] With the fixing bolts in a loose state, the camshaft phase adjuster slides circumferentially relative to the end face of the camshaft. When the angle value output by the protractor reaches the set target angle, the rotational driving force applied to the crankshaft stops, and the crankshaft and camshaft phase adjuster stop rotating.
[0027] Preferably, the specific operations of inserting the phase adjuster fixing fixture into the front cover again and abutting against the camshaft phase adjuster in the opposite direction, and tightening the fixing bolts include:
[0028] Insert the insertion part of the phase adjuster fixing fixture into the through hole of the front cover along the axial direction again. The two protrusions enter the two grooves respectively. Manually rotate the phase adjuster fixing fixture counterclockwise until the counterclockwise side wall of the two protrusions rigidly abuts against the circumferential counterclockwise side wall of the corresponding two grooves.
[0029] An external tightening tool is passed through the through hole and tightened clockwise to secure the fixing bolt. The fixing bolt presses the camshaft phase adjuster against the axial end face of the camshaft. The clockwise torque transmitted from the fixing bolt to the camshaft phase adjuster is carried by the front cover through the phase adjuster fixing fixture.
[0030] Preferably, the specific operation of contacting the camshaft phase adjuster further includes:
[0031] While maintaining a rigid contact, the external locking bolts pass through the three through slots on the outer periphery of the phase adjuster fixing fixture and are screwed into the corresponding threaded holes on the front cover, thus locking the phase adjuster fixing fixture onto the front cover.
[0032] Preferably, the circumferential gap between the protrusion and the groove satisfies the following dimensional relationship:
[0033] The circumferential arc width angle of the groove of the camshaft phase adjuster is greater than the circumferential arc width angle of the protrusion of the phase adjuster fixing fixture;
[0034] The total circumferential free clearance angle after the phase adjuster fixture and the camshaft phase adjuster are fitted together is equal to the difference between the circumferential closed arc angle of the groove on the camshaft phase adjuster and the circumferential structural arc angle of the protrusion on the phase adjuster fixture.
[0035] Preferably, the specific operation of applying a reverse rotational torque to the fixing bolt to loosen the fixing bolt further includes:
[0036] The external tightening tool drives the fixing bolt to rotate counterclockwise a preset number of turns. The axial clamping end face of the fixing bolt leaves the contact surface of the camshaft phase adjuster, and the fixing bolt is in a non-clamped axially loose state. The threaded section of the fixing bolt remains in the internal threaded hole of the camshaft.
[0037] The remaining thread engagement length of the fixing bolt in the internal threaded hole of the camshaft is equal to the total effective length of the fixing bolt thread segment minus the axial outward movement distance of the fixing bolt during the loosening process. The remaining thread engagement length is set to be greater than or equal to 5mm.
[0038] The above solution achieves the following beneficial technical effects:
[0039] This invention achieves locking and force control of the camshaft and phase adjuster by removing the observation hole plug on the upper cover, inserting a locating pin, and inserting a camshaft phase adjuster fixing fixture from the front cover. This method avoids the complete disassembly of the engine cover and internal timing chain system, allowing operators to directly perform real-time phase adjustments in an engine assembly or bench testing environment, effectively reducing disassembly and assembly workload and shortening adjustment time.
[0040] This invention uses a camshaft locating pin that passes through an observation hole and is inserted into the camshaft locating groove to rigidly lock the camshaft at a defined reference position, ensuring it remains stationary during adjustment. Simultaneously, a protractor attached to the crankshaft flywheel monitors the actual rotation of the crankshaft. By recording the initial angle and controlling the crankshaft to rotate to a specified angle, the relative angle adjustment is quantified and visualized, eliminating visual errors inherent in conventional mechanical alignment operations.
[0041] This invention, before loosening and tightening the camshaft phase adjuster fixing bolts, involves rotating the fixing fixture clockwise and counterclockwise respectively, thus ensuring that the protrusion of the fixture forms a rigid abutment with the side wall of the adjuster's groove. This feature directly guides and unloads the reaction torque generated during bolt installation and removal onto the front cover, avoiding the impact of huge torque on the timing chain drive system and preventing accidental slippage of the camshaft phase adjuster during secondary bolt tightening, ensuring accurate fixation of the target phase. Attached Figure Description
[0042] Figure 1 This is a flowchart of the engine camshaft phase adjustment control method of the present invention;
[0043] Figure 2 This is a schematic diagram of the assembly structure of the upper cover and the screw plug of the present invention;
[0044] Figure 3 This is a schematic diagram of the assembly structure of the front cover and the camshaft phase adjuster fixing fixture of the present invention;
[0045] Figure 4 This is a schematic diagram of the assembly structure of the protractor and crankshaft flywheel of the present invention;
[0046] Figure 5 This is a schematic diagram of the chain drive system structure of the present invention;
[0047] Figure 6 This is an exploded view of the camshaft phase adjuster and fixing bolt of the present invention;
[0048] Figure 7 This is a schematic diagram of the camshaft and locating pin assembly structure of the present invention;
[0049] Figure 8 This is a schematic cross-sectional view of the working state of the camshaft locating pin of the present invention;
[0050] Figure 9 This is a schematic diagram of the camshaft phase adjuster fixing fixture structure of the present invention;
[0051] Figure 10 This is a schematic diagram showing the camshaft phase adjuster of the present invention rotating to contact the side wall with the fixed fixture.
[0052] Among them, 11, upper cover; 111, observation hole; 112, screw plug; 12, front cover; 13, flywheel; 14, crankshaft; 151, crankshaft sprocket; 152, timing chain; 153, camshaft phase adjuster; 1531, groove; 154, fixing bolt; 16, camshaft; 161, U-shaped positioning groove; 21, angle marker; 22, camshaft positioning pin; 221, mounting part; 222, working part; 23, phase adjuster fixing fixture; 231, insertion part; 232, protrusion; 233, through hole; 234, through groove. Detailed Implementation
[0053] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0054] See attached document Figure 1 Appendix Figure 2 Appendix Figure 4 and attached Figure 8 The present invention provides a control method for engine camshaft phase adjustment, which may include:
[0055] During the initial state confirmation and camshaft zero-position locking phase, the external operator first removes the plug 112 installed in the observation hole 111 of the upper cover 11. Specifically, the plug 112 is unscrewed from the observation hole 111 and removed by applying rotational torque with an external tool, thereby fully exposing the observation hole 111 of the upper cover 11 to the outside, so as to facilitate subsequent visual observation of internal engine components and installation of tooling parts through the observation hole 111. Subsequently, the protractor 21 is placed and fixed on the outer surface of the flywheel 13. Specifically, the protractor 21 is attached to the outer circumferential surface of the flywheel 13 by its own magnetic adsorption function. Since the flywheel 13 is rigidly fixed on the crankshaft 14, the protractor 21 can rotate synchronously in the circumference along with the flywheel 13 and the crankshaft 14, thereby enabling the protractor 21 to measure and output the change in angular spatial position of the crankshaft 14 in real time during subsequent rotation.
[0056] After the adsorption installation of the angle marker 21 is completed, the external operator applies a clockwise rotational torque to the crankshaft 14 to perform a clockwise rotational operation. Under the clockwise rotational driving force, the crankshaft 14 rotates clockwise around its own central axis. This rotation synchronously drives the crankshaft sprocket 151, which is rigidly connected to it, to rotate clockwise. The crankshaft sprocket 151 transmits the rotational torque downstream through the timing chain 152, which in turn drives the timing chain 152 to rotate. The timing chain 152 then drives the camshaft phase adjuster 153, which is also meshed with it, to rotate. With the fixing bolt 154 axially tightened, the camshaft phase adjuster 153 coaxially drives the camshaft 16 to rotate clockwise synchronously. While the crankshaft 14 and camshaft 16 are rotating clockwise, the operator continuously observes the engine interior through the observation hole 111 exposed on the upper cover 11 to capture and determine the spatial position of the U-shaped positioning groove 161 machined on the outer circumferential surface of the camshaft 16 in real time. When the operator observes through the observation hole 111 that the U-shaped positioning groove 161 of the camshaft 16 has rotated to a vertical position, the rotational driving force applied to the crankshaft 14 is immediately stopped, causing the crankshaft 14, crankshaft sprocket 151, timing chain 152, camshaft phase adjuster 153, and camshaft 16 to all stop rotating and remain stationary.
[0057] After the crankshaft 14 stops rotating and the U-shaped locating groove 161 of the camshaft 16 is stably held in the upright position, the operator aligns the camshaft locating pin 22 axially with the observation hole 111 of the upper cover 11 and screws it in. Specifically, the external thread of the mounting portion 221 of the camshaft locating pin 22 is aligned and engaged with the internal thread of the observation hole 111 of the upper cover 11, and the mounting portion 221 is fully screwed into the observation hole 111 by applying a tightening torque. As the mounting portion 221 is pushed into the observation hole 111, the cylindrical working portion 222, which extends coaxially and integrally from the front end of the mounting portion 221, extends axially into the engine and is inserted into the U-shaped locating groove 161, which is in the upright position. The cylindrical outer circumferential surface of the working part 222 makes bidirectional rigid contact with the two parallel sidewalls of the U-shaped positioning groove 161. Simultaneously, the bottommost end face of the working part 222 directly abuts against the bottom surface of the U-shaped positioning groove 161, thus completely and rigidly locking the camshaft 16 in its circumferential rotational freedom, ensuring that the camshaft 16 remains stably at its current zero reference point without rotation. After the camshaft positioning pin 22 completely locks the camshaft 16, the operator reads and records the current crankshaft angle value displayed by the protractor 21 attached to the flywheel 13. This value constitutes the initial crankshaft angle value before adjustment in this control method, and is defined as the initial angle α in subsequent control logic.
[0058] See attached document Figure 1Appendix Figure 3 Appendix Figure 6 and attached Figure 10 This invention provides a control method during the tooling intervention and camshaft-crankshaft relative angle adjustment stages, which may include:
[0059] After initial state confirmation and zero-position locking of camshaft 16, the operator performs tooling intervention and relative angle adjustment. The operator inserts the insertion part 231 of phase adjuster fixing tool 23 axially into the through hole of front cover 12. During axial insertion, two protrusions 232 extending forward from the front end face of phase adjuster fixing tool 23 enter the two grooves 1531 opened on the outer end face of camshaft phase adjuster 153. Since the circumferential width of protrusion 232 is smaller than the circumferential width of groove 1531, at this time, protrusion 232 and circumferential sidewall of groove 1531 are separated and have a gap. Then, the phase adjuster fixing tool 23 is manually rotated clockwise, causing protrusion 232 to shift circumferentially until the clockwise sidewall of the two protrusions 232 rigidly abuts against the corresponding clockwise sidewall of the two grooves 1531, thereby eliminating the circumferential fit gap in the rotation direction. While maintaining this rigid contact state, the external locking bolts pass through the three through slots 234 opened on the outer peripheral edge of the phase adjuster fixing fixture 23 and are screwed into the corresponding threaded holes on the front cover 12, thereby locking and fixing the phase adjuster fixing fixture 23 onto the front cover 12.
[0060] After the phase adjuster fixing fixture 23 is locked onto the front cover 12, an external tightening tool passes axially through the through hole 233 opened at the central axis of the phase adjuster fixing fixture 23. The external tightening tool enters the clearance space inside the through hole 233 and engages with the head of the fixing bolt 154. The operator applies a reverse rotational torque to the fixing bolt 154 using the external tightening tool to loosen the fixing bolt 154. During the application of the reverse loosening torque, since the protrusion 232 and the groove 1531 are already in a circumferential clockwise rigid contact state, the loosening reaction torque on the camshaft phase adjuster 153 is directly borne by the phase adjuster fixing fixture 23 and transmitted to the front cover 12, thereby preventing the torque from causing unexpected rotational impact on the timing chain 152 or the camshaft 16. The external tightening tool drives the fixing bolt 154 to move outward axially until the axial end face of the fixing bolt 154 is released from the axial pressing state on the camshaft phase adjuster 153, so that the fixing bolt 154 is in a loose state without being pressed. At this time, the threaded section of the fixing bolt 154 is still retained in the internal threaded hole of the camshaft 16 and does not come off.
[0061] After the fixing bolt 154 is released from the axial clamping state, the operator loosens and unscrews the external locking bolt that was previously screwed into the front cover 12 through the through groove 234. After releasing the constraint of the external locking bolt, the operator pulls the phase adjuster fixing fixture 23 axially outward, causing the phase adjuster fixing fixture 23 to be pulled out of the front cover 12. During the pulling process, the insertion part 231 exits from the through hole of the front cover 12, and at the same time, the two protrusions 232 also completely move axially out of the two grooves 1531 of the camshaft phase adjuster 153, thereby releasing all external circumferential rigid constraints of the phase adjuster fixing fixture 23 on the camshaft phase adjuster 153.
[0062] After the phase adjuster fixing fixture 23 is completely removed, the operator adjusts the relative angle between the crankshaft 14 and the camshaft 16. The operator applies a clockwise rotational driving force to the crankshaft 14, causing it to rotate clockwise around its own axis. The clockwise rotation of the crankshaft 14 drives the crankshaft sprocket 151 to rotate synchronously, and through the transmission action of the timing chain 152, drives the camshaft phase adjuster 153 to rotate clockwise synchronously. At this time, because the fixing bolt 154 is in a loose state, the camshaft phase adjuster 153 slides freely in a circumferential direction relative to the end face of the camshaft 16. At the same time, because the working part 222 of the camshaft locating pin 22 is still inserted in the U-shaped locating groove 161 of the camshaft 16, the camshaft 16 remains stationary under the bidirectional rigid limiting action and does not rotate with the camshaft phase adjuster 153.
[0063] As the crankshaft 14, carrying the camshaft phase adjuster 153, continues to rotate clockwise, the protractor 21, rigidly attached to the flywheel 13, rotates synchronously with the flywheel 13 and the crankshaft 14, outputting the current angle change value of the crankshaft 14 in real time. The operator continuously rotates the crankshaft 14 and observes the angle reading of the protractor 21. When the angle value output by the protractor 21 reaches the set target angle, the rotational driving force applied to the crankshaft 14 is immediately stopped, causing the crankshaft 14 and the camshaft phase adjuster 153 to stop rotating. At this point, the crankshaft 14 has completed a relative angle adjustment with respect to the stationary camshaft 16. The relative adjustment angle of the crankshaft 14 relative to the camshaft 16 is equal to the difference between the target angle obtained by the protractor 21 in real time when the crankshaft 14 stops rotating at the adjustment endpoint and the initial angle recorded by the protractor 21 when the camshaft 16 is locked at the zero reference point at the adjustment starting point. By controlling the crankshaft 14 to rotate from the initial angle to the target angle, the relative circumferential angle between the camshaft phase adjuster 153 and the camshaft 16 is quantitatively changed. The target angle is defined as the target angle β in the subsequent control logic, thereby realizing the control and real-time adjustment of the valve timing phase.
[0064] See attached document Figure 1 Appendix Figure 10 and attached Figure 6 This invention provides a control method for the phase secondary locking and system reset recovery phases, which may include:
[0065] After the crankshaft 14 reaches the target angle β by rotating clockwise, the operator performs a secondary phase locking operation to fix the adjusted relative phase. The operator then inserts the insertion part 231 of the phase adjuster fixing fixture 23 axially into the through hole of the front cover 12. During this process, the two protrusions 232 located at the axial front end of the insertion part 231 enter the two grooves 1531 on the outer end face of the camshaft phase adjuster 153, respectively. Since there is a circumferential gap between the protrusions 232 and the grooves 1531, the operator manually rotates the phase adjuster fixing fixture 23 counterclockwise, causing the protrusions 232 to move in the opposite direction circumferentially until the counterclockwise sidewalls of the two protrusions 232 rigidly abut against the corresponding counterclockwise sidewalls of the two grooves 1531, thereby completely eliminating the circumferential fit gap in this rotational direction. With the counterclockwise contact in place, the external locking bolts pass through the three through slots 234 on the edge of the phase adjuster fixing fixture 23 and are screwed into the threaded holes on the front cover 12, thus rigidly locking the phase adjuster fixing fixture 23 onto the front cover 12.
[0066] After the phase adjuster fixing fixture 23 is locked onto the front cover 12, the external tightening tool passes through the through hole 233 at the axial position of the phase adjuster fixing fixture 23 and makes a transmission connection with the head of the fixing bolt 154. The operator operates the external tightening tool to tighten the fixing bolt 154 clockwise according to the preset torque value. During the tightening process, the fixing bolt 154 generates a clamping force inward, pressing the camshaft phase adjuster 153 against the axial end face of the camshaft 16, so that the camshaft phase adjuster 153 and the camshaft 16 return to a rigid connection state. Since the protrusion 232 of the phase adjuster fixing fixture 23 and the groove 1531 are in a rigid counterclockwise contact state, the clockwise torque transmitted by the fixing bolt 154 to the camshaft phase adjuster 153 during the tightening process is effectively borne by the front cover 12 through the phase adjuster fixing fixture 23, thereby eliminating the influence of the tightening torque on the timing chain 152 and the camshaft 16 which has been locked by the camshaft positioning pin 22, ensuring that the adjusted target angle β does not dynamically shift.
[0067] After the fixing bolt 154 reaches the specified torque and is in a tightened state, the operator first removes the external locking bolts used to fix the phase adjuster fixing fixture 23, and pulls the phase adjuster fixing fixture 23 outward axially from the front cover 12. Then, the operator applies a reverse rotational torque to the camshaft locating pin 22 mounted on the upper cover 11, completely unscrewing the mounting part 221 of the camshaft locating pin 22 from the observation hole 111 of the upper cover 11, causing the working part 222 to exit from the U-shaped locating groove 161 of the camshaft 16, thereby releasing the rotational constraint on the camshaft 16. Finally, the plug 112 is screwed back in and tightened into the observation hole 111 of the upper cover 11, and the marker 21 attached to the flywheel 13 is removed, completing the entire engine camshaft phase adjustment and system reset process.
[0068] See attached document Figure 10 This invention provides a core control logic and circumferential backlash elimination mechanism in a control method for engine camshaft phase adjustment, which may include:
[0069] A predetermined circumferential clearance is provided between the protrusion 232 of the phase adjuster fixing fixture 23 and the groove 1531 of the camshaft phase adjuster 153. The purpose of this circumferential clearance is to compensate for the dimensional tolerances of the engine components and the special tooling during the manufacturing process, ensuring that when the phase adjuster fixing fixture 23 is inserted axially into the front cover 12 and approaches the camshaft phase adjuster 153, the protrusion 232 can enter the groove 1531, avoiding jamming due to tolerances, thereby ensuring smooth operation of on-site assembly and tooling intervention.
[0070] Specifically, the circumferential arc width angle of the groove 1531 of the camshaft phase adjuster 153 is greater than the circumferential arc width angle of the protrusion 232 of the phase adjuster fixing fixture 23. The difference in their geometric dimensions determines the total circumferential free clearance in the initial state. The total circumferential free clearance angle after the phase adjuster fixing fixture 23 and the camshaft phase adjuster 153 are engaged is equal to the difference between the circumferential closed arc angle of the groove 1531 on the camshaft phase adjuster 153 and the circumferential structural arc angle of the protrusion 232 on the phase adjuster fixing fixture 23. While this total circumferential free clearance angle ensures installation tolerance, if bolting is performed directly without eliminating the clearance, the circumferential play caused by the clearance will lead to dynamic drift in phase adjustment. Therefore, this invention completely eliminates the adverse effects of this clearance through a bidirectional rotational abutment mechanism.
[0071] Before loosening the fixing bolt 154, manually rotate the phase adjuster fixing fixture 23 clockwise, causing the protrusion 232 to move unidirectionally clockwise within the groove 1531 until the clockwise sidewall of the protrusion 232 rigidly contacts and adheres to the clockwise inner sidewall of the groove 1531. At this point, the total circumferential free clearance angle is compressed to 0 degrees in the clockwise direction, thereby establishing a rigid positioning reference surface in the clockwise rotational degree of freedom. When the external tightening tool is inserted into the through hole 233 and a reverse loosening torque is applied to the fixing bolt 154, due to the end face friction between the fixing bolt 154 and the camshaft phase adjuster 153, the loosening torque tends to drive the camshaft phase adjuster 153 to move in the same direction. The established clockwise rigid contact interface can provide an equal and opposite rigid damping torque, which completely guides and unloads the disturbance torque onto the front cover 12 through the body of the phase adjuster fixing fixture 23 and the through groove 234, thereby blocking the transmission of the loosening torque to the timing chain 152 and ensuring the structural stability of the camshaft phase adjuster 153 at the moment the bolt is loosened.
[0072] After the crankshaft 14 is rotated to the target angle and the relative angle adjustment is completed, the phase adjuster fixing fixture 23 is manually rotated counterclockwise before the fixing bolt 154 is tightened again. At this time, the protrusion 232 moves unidirectionally counterclockwise within the groove 1531 until the counterclockwise side wall of the protrusion 232 makes rigid contact with the counterclockwise inner side wall of the groove 1531. This action completely eliminates the total circumferential free clearance angle in the counterclockwise direction and reduces it to 0 degrees, thereby re-establishing the rigid boundary condition in the opposite direction. When the external tightening tool applies a clockwise tightening torque to the fixing bolt 154, the clockwise dragging torque on the camshaft phase adjuster 153 directly presses against the already contacted counterclockwise side wall, rigidly constraining the alternating load on the front cover 12 through the locking path, preventing the tightening torque from causing the camshaft phase adjuster 153 to rotate slightly circumferentially, thereby locking the adjusted relative phase and eliminating the dynamic adjustment error caused by the tooling fit play.
[0073] During the tightening of the fixing bolt 154 to the specified torque, the torque transmission and balance of the entire valve train locking system satisfy the following mechanical relationship: the reaction torque absorbed and borne by the rigid contact interface of the front cover 12 through the phase adjuster fixing fixture 23 is equal to the difference between the input tightening torque applied to the fixing bolt 154 by the external tightening tool and the inherent frictional resistance torque between the threaded pair and the flange end face of the fixing bolt 154. Through the bidirectional unilateral contact control of the phase adjuster fixing fixture 23, the dynamic error is completely eliminated through staged manual fine-tuning intervention under the premise of tolerance clearance, thereby ensuring that the relative angle adjustment accuracy between the crankshaft 14 and the camshaft 16 is completely equivalent to the measurement reading accuracy of the protractor 21.
[0074] See attached document Figure 1 Appendix Figure 3 and attached Figure 6 The present invention provides an extended embodiment and alternative to the control method for engine camshaft phase adjustment, which may include:
[0075] The control method of this invention demonstrates broad applicability under both engine assembly line production and bench testing conditions. In engine assembly line conditions, with the engine in the assembly stage, operators can directly perform real-time online phase fine-tuning of the engine by removing the plug 112 at the observation hole 111 of the upper cover 11 and fixing the protractor 21 to the flywheel 13. In bench testing conditions, with the engine already mounted on the test bench, when comparing the effects of different valve timing phases, operators do not need to completely remove the engine from the test bench. They can directly use the camshaft locating pin 22 to lock the U-shaped locating groove 161 of the camshaft 16 through the observation hole 111 in its original position on the bench. Simultaneously, by installing the phase adjuster fixing fixture 23 on the front cover 12, the fixing bolts 154 can be loosened for in-situ phase adjustment, shortening the disassembly and assembly cycle of the bench test.
[0076] In another alternative embodiment of the invention, to improve the error prevention capability of parts during the adjustment process, a safety design is provided to prevent the fixing bolt 154 from falling off completely, only loosening it. In the step where the operator loosens the fixing bolt 154 to release the axial clamping force between the camshaft phase adjuster 153 and the camshaft 16, the external tightening tool only drives the fixing bolt 154 to rotate counterclockwise a preset number of turns, causing the axial clamping end face of the fixing bolt 154 to leave the contact surface of the camshaft phase adjuster 153, thus placing the fixing bolt 154 in a loose, uncompressed axially loose state. At this time, a portion of the threaded section of the fixing bolt 154 remains in the internal threaded hole of the camshaft 16, without completely disengaging from the camshaft 16.
[0077] In this anti-fall-out alternative design, the thread engagement state of the fixing bolt 154 during axial adjustment satisfies the following linear dimensional relationship: when the crankshaft 14 is adjusted relative to the camshaft 16, the remaining thread engagement length of the fixing bolt 154 in the internal threaded hole of the camshaft 16 is equal to the total effective length of the threaded section of the fixing bolt 154 minus the axial outward movement distance of the fixing bolt 154 during the loosening process. To ensure that the fixing bolt 154 will not fall out of the camshaft 16 due to gravity or rotational vibration when the crankshaft 14 drives the camshaft phase adjuster 153 to slide freely relative to the stationary camshaft 16, the remaining thread engagement length is set to a safety value greater than or equal to 5mm. By maintaining this remaining thread engagement length, the risk of disassembling the entire machine caused by the fixing bolt 154 falling into the internal cavity of the front cover 12 after complete disengagement is avoided.
[0078] In another modified embodiment, the control method of the present invention is also applicable to other valve train modifications with a conventional camshaft sprocket structure. In this valve train, the camshaft phase adjuster 153 is replaced with a conventional non-phase-adjustable camshaft sprocket, which also has two grooves 1531 on its end face for inserting with two protrusions 232 of the phase adjuster fixing fixture 23 with circumferential free clearance. During operation or adjustment of the entire machine, the crankshaft 14 drives the camshaft sprocket to rotate synchronously via the crankshaft sprocket 151 and the timing chain 152. When fine-tuning and calibration of the valve timing between the fixed camshaft sprocket and the camshaft 16 is required, the camshaft locating pin 22 is used to lock the U-shaped locating groove 161 of the camshaft 16, and the protrusion 232 of the phase adjuster fixing fixture 23 is rigidly abutted against the side wall of the groove 1531 of the camshaft sprocket in a clockwise or counterclockwise bidirectional phase to bear the alternating torque generated by the fixing bolt 154 when it is loosened or tightened. Thus, in a normal sprocket valve timing mechanism, valve timing phase adjustment can be completed without disassembling the upper cover 11 and the front cover 12.
[0079] Finally, it should be noted that 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A control method for engine camshaft phase adjustment, characterized in that, Includes the following steps: In the initial state confirmation and camshaft zero-position locking stage, remove the screw plug (112) in the observation hole (111) of the upper cover (11), attach the protractor (21) to the flywheel (13) sleeved on the crankshaft (14), rotate the crankshaft (14) to rotate the U-shaped positioning groove (161) of the camshaft (16) to the positive vertical direction, screw the camshaft positioning pin (22) into the observation hole (111) and insert it into the U-shaped positioning groove (161), and record the initial angle; During the tooling intervention and camshaft-crankshaft relative angle adjustment stage, the phase adjuster fixing tool (23) is inserted into the front cover (12) and abuts against the camshaft phase adjuster (153). The fixing bolt (154) is loosened by an external tightening tool. After pulling out the phase adjuster fixing tool (23), the crankshaft (14) is rotated to the target angle. During the phase secondary locking and system reset recovery phase, the phase adjuster fixing fixture (23) is inserted into the front cover (12) again and abuts against the camshaft phase adjuster (153) in the opposite direction. The fixing bolt (154) is tightened. The phase adjuster fixing fixture (23), camshaft positioning pin (22) and angle gauge (21) are removed. The screw plug (112) is screwed back in and tightened in the observation hole (111).
2. The control method for engine camshaft phase adjustment according to claim 1, characterized in that, The specific operations of attaching the protractor (21) to the flywheel (13) mounted on the crankshaft (14) and recording the initial angle include: The protractor (21) is attached to the outer circumferential surface of the flywheel (13), and the protractor (21) rotates synchronously in the circumferential direction along with the flywheel (13) and the crankshaft (14); After the camshaft (16) is locked by the camshaft positioning pin (22), the current crankshaft angle value displayed by the protractor (21) attached to the flywheel (13) is read and recorded and defined as the initial angle.
3. The control method for engine camshaft phase adjustment according to claim 1, characterized in that, The specific operation of screwing the camshaft positioning pin (22) into the observation hole (111) and inserting it into the U-shaped positioning groove (161) includes: Align the external thread of the mounting part (221) of the camshaft positioning pin (22) with the internal thread of the observation hole (111) of the upper cover (11), and screw the mounting part (221) completely into the observation hole (111) by applying a tightening torque; The cylindrical working part (222) extending coaxially at the front end of the mounting part (221) extends into the engine along the axial direction and is inserted into the U-shaped positioning groove (161) in the positive vertical direction. The cylindrical outer circumferential surface of the working part (222) and the two parallel side walls of the U-shaped positioning groove (161) make bidirectional rigid contact and fit together. The bottom end face of the working part (222) in the axial direction directly abuts against the bottom surface of the U-shaped positioning groove (161).
4. The control method for engine camshaft phase adjustment according to claim 1, characterized in that, The specific operation of inserting the phase adjuster fixing fixture (23) into the front cover (12) and abutting against the camshaft phase adjuster (153) includes: Insert the insertion part (231) of the phase adjuster fixing fixture (23) into the through hole of the front cover (12) along the axial direction; Two protrusions (232) extending forward from the front end of the phase adjuster fixing fixture (23) enter into two grooves (1531) opened on the outer end face of the camshaft phase adjuster (153), respectively. The protrusions (232) and the circumferential sidewalls of the grooves (1531) are separated and have a gap.
5. The control method for engine camshaft phase adjustment according to claim 4, characterized in that, The specific operations of contacting the camshaft phase adjuster (153) and loosening the fixing bolt (154) using an external tightening tool include: Manually rotate the phase adjuster fixing fixture (23) clockwise until the clockwise sidewalls of the two protrusions (232) rigidly abut against the circumferential clockwise sidewalls of the corresponding two grooves (1531); An external tightening tool passes axially through a through hole (233) opened at the central axis of the phase adjuster fixing fixture (23) and engages with the head of the fixing bolt (154) to apply a reverse rotation torque to the fixing bolt (154), loosening the fixing bolt (154). The loosening reaction torque on the camshaft phase adjuster (153) is carried by the phase adjuster fixing fixture (23) and transmitted to the front cover (12).
6. The control method for engine camshaft phase adjustment according to claim 1, characterized in that, The specific operation of rotating the crankshaft (14) to the target angle includes: A clockwise rotational driving force is applied to the crankshaft (14), and the rotation of the crankshaft (14) synchronously drives the crankshaft sprocket (151) rigidly connected to the crankshaft (14) to rotate clockwise. The crankshaft sprocket (151) drives the camshaft phase adjuster (153) to rotate through the timing chain (152) meshing with the crankshaft sprocket (151). When the fixing bolt (154) is in a non-tightened state, the camshaft phase adjuster (153) slides circumferentially relative to the end face of the camshaft (16). When the angle value output by the angle gauge (21) reaches the set target angle, the rotational driving force applied to the crankshaft (14) is stopped, and the crankshaft (14) and the camshaft phase adjuster (153) stop rotating.
7. The control method for engine camshaft phase adjustment according to claim 5, characterized in that, The specific operations of inserting the phase adjuster fixing fixture (23) into the front cover (12) again and abutting against the camshaft phase adjuster (153) and tightening the fixing bolt (154) include: Insert the insertion part (231) of the phase adjuster fixing fixture (23) into the through hole of the front cover (12) along the axial direction again. The two protrusions (232) enter the two grooves (1531) respectively. Manually rotate the phase adjuster fixing fixture (23) counterclockwise until the counterclockwise sidewalls of the two protrusions (232) rigidly abut against the circumferential counterclockwise sidewalls of the corresponding two grooves (1531). An external tightening tool passes through the through hole (233) and tightens the fixing bolt (154) clockwise. The fixing bolt (154) presses the camshaft phase adjuster (153) onto the axial end face of the camshaft (16). The clockwise torque transmitted to the camshaft phase adjuster (153) by the fixing bolt (154) is carried by the front cover (12) through the phase adjuster fixing fixture (23).
8. The control method for engine camshaft phase adjustment according to claim 5, characterized in that, The specific operation of contacting the camshaft phase adjuster (153) also includes: While maintaining a rigid contact, the external locking bolt passes through the three through slots (234) on the outer periphery of the phase adjuster fixing fixture (23) and is screwed into the corresponding threaded holes on the front cover (12), thereby locking the phase adjuster fixing fixture (23) onto the front cover (12).
9. The control method for engine camshaft phase adjustment according to claim 4, characterized in that, The circumferential gap between the protrusion (232) and the groove (1531) satisfies the following dimensional relationship: The circumferential arc width angle of the groove (1531) of the camshaft phase adjuster (153) is greater than the circumferential arc width angle of the protrusion (232) of the phase adjuster fixing fixture (23); The total circumferential free clearance angle after the phase adjuster fixing fixture (23) and the camshaft phase adjuster (153) are engaged is equal to the difference between the circumferential closed arc angle of the groove (1531) on the camshaft phase adjuster (153) and the circumferential structural arc angle of the protrusion (232) on the phase adjuster fixing fixture (23).
10. The control method for engine camshaft phase adjustment according to claim 5, characterized in that, The specific operation of applying a reverse rotational torque to the fixing bolt (154) to loosen the fixing bolt (154) further includes: The external tightening tool drives the fixing bolt (154) to rotate counterclockwise a preset number of turns. The axial pressing end face of the fixing bolt (154) leaves the contact surface of the camshaft phase adjuster (153). The fixing bolt (154) is in a non-pressurized axially loose state. The threaded section of the fixing bolt (154) remains in the internal threaded hole of the camshaft (16). The remaining thread engagement length of the fixing bolt (154) in the internal threaded hole of the camshaft (16) is equal to the total effective length of the thread segment of the fixing bolt (154) minus the axial outward movement distance of the fixing bolt (154) during the loosening process. The remaining thread engagement length is set to be greater than or equal to 5 mm.