Automobile brake clearance ratchet type constant value self-adjusting arm and adjusting method thereof

Abstract

The present application relates to the field of automobile brake technology, and provides a kind of automobile brake clearance ratchet type fixed value self-adjusting arm and its adjusting method, including shell and the big worm, big worm gear, control disc, gear, small worm, small worm gear, taper clutch, tine clutch, small shaft, ratchet wheel, ratchet wheel cover and pawl being arranged in shell.The control disc is solidly connected with control arm, the control arm is fixed on the car, and the shell can rotate relative to the control disc.Ratchet wheel cover can limit pawl only turn over an effective tooth groove relative to ratchet wheel when brake return, called "fixed value adjusting method", replaces the "extreme adjusting method" that can turn over multiple saw-shaped teeth each time brake return at present, and the tooth angle of ratchet tooth is equal to the tooth angle of saw-shaped tooth.The fixed value adjusting method of the present application is less likely to adjust the gap to be very small in hot state, reduces the occurrence of "over-adjustment" after cooling, avoids automobile "dragging" or even "lock", and causes traffic accident.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile braking technology, in particular to a kind of automobile brake clearance ratchet type fixed value self-adjusting arm and its adjusting method. BACKGROUND

[0002] The drum brake of automobile is through the compression and separation between brake shoe (including friction block) and brake drum on the wheel to brake and release brake. To make the automobile can normally travel, there will be a reserved gap ζ between shoe and drum, and the self-adjusting arm has a reserved gap angle C corresponding thereto. Since the gap will increase due to the wear of brake shoe friction block and other components thermal expansion and other reasons, the increased part is called excess gap β, and the self-adjusting arm has excess gap angle Ce corresponding thereto.

[0003] The existing self-adjusting arm can gradually reduce β. The β at hot state will be very large, and the actual gap after multiple adjustments is close to the reserved gap ζ. When parking or cooling, the actual gap may be less than the reserved gap ζ, which is called "over-adjustment" in the industry. "Over-adjustment" is caused by physical reasons such as thermal expansion and cannot be avoided. When "over-adjustment" is serious, "dragging" or "lock" may occur, resulting in traffic accidents.

[0004] The adjustment principle of all kinds of self-adjusting arms in the world at present is that the gap between shoe and drum increases, the rotation angle (C+Ce) of self-adjusting arm during braking also increases, and Ce is the basis for adjustment during return. The adjustment amount Y of single rotation angle of self-adjusting arm increases with the increase of Ce, that is, Y=fCe, f is a fixed proportion coefficient, and Y is a function of excess gap angle Ce. The gap adjustment mechanism of existing sawtooth self-adjusting arm is "sawtooth clutch", and the adjustment amount Y is increased or decreased according to step law, Y=fnθ, n represents the number of sawtooth, which is 1, 2, 3,..., θ is the angle between two sawtooth, see Figure 1 The industry hopes to reduce the single adjustment amount, but due to structural reasons, the proportion coefficient f cannot be too small, and n is a random variable which cannot be intervened. When the temperature of brake drum is higher, n is larger, nθ is also larger, the adjustment amount is larger, and the possibility of "over-adjustment" after cooling is higher. In view of the reality, a consensus has been formed in foreign countries for more than thirty years that the generation of "over-adjustment" is a physical reason, and since it cannot be avoided, the driver can only manually adjust the small gap to close to the reserved gap ζ in time according to experience.

[0005] We call the above adjustment method based on Y=fnθ as "extreme value method". SUMMARY

[0006] The technical problem to be solved by the present application is to reduce the occurrence of "over-adjustment", prevent the automobile from "dragging" or "locking", and cause traffic accidents.

[0007] In order to solve the above technical problems, the present application provides a kind of automobile brake clearance ratchet type fixed value self-adjusting arm, including shell and the big worm, big worm wheel, control disc, gear, small worm, small worm wheel, taper clutch, tine clutch, small shaft, ratchet wheel, ratchet wheel cover and pawl being arranged in shell, the tooth angle of the ratchet wheel is equal to the tooth angle of the above saw-shaped tooth, the control disc is fixedly connected with control arm, the control arm is fixed on the car, the shell can rotate relative to the control disc, the gear can rotate in the shell, and the gear is engaged with the control disc, the tine clutch includes left half clutch and right half clutch, the left half clutch and the right half clutch can be engaged, the left half clutch is fixedly connected with the small worm, the right half clutch is axially slidably connected with the gear, the small worm is engaged with the small worm wheel, the small worm wheel is sleeved on the big worm, is connected by the taper clutch, the big worm is engaged with the big worm wheel, the ratchet wheel is fixedly connected with the small worm, the ratchet wheel cover is fixedly connected with the shell, the ratchet wheel cover is provided with three notches, the front surface of the gear is provided with three recesses, one end of each pawl is hinged in each recess, and the other end of the pawl is tightly attached to the surface of the ratchet wheel cover or the ratchet wheel under the action of leaf spring.

[0008] A kind of adjusting method of automobile brake clearance ratchet type fixed value self-adjusting arm, characterized in that, including the following processes:

[0009] The initial state of self-adjusting arm after being installed on the car is that the median line of S-camshaft is right-biased by an angle C, and the central axis of self-adjusting arm coincides with 0 ° reference line;

[0010] I. Record the adjustment basis during braking process-just skip one effective tooth groove:

[0011] Step 1: when the driver steps on the brake pedal, the self-adjusting arm rotates counterclockwise, when it rotates through the reserved clearance angle C, the brake shoe and the brake drum are not completely contacted; the gear rotates, so that the pawl rotates relative to the ratchet wheel, the pawl rotates through an angle equivalent to C from the tooth groove A to a certain point in the upper part of the tooth groove A;

[0012] Step 2: the self-adjusting arm continues to rotate counterclockwise, when it rotates through the angle Ce', the pawl falls into the tooth groove B, and the brake shoe and the brake drum are not completely contacted;

[0013] Step 3: the self-adjusting arm continues to rotate counterclockwise, when it rotates through the difference between Ce and Ce', the pawl may still rotate in the tooth groove B, or rotate through the notch of the ratchet wheel cover and be lifted by the outer surface of the ratchet wheel cover, at this time, the brake shoe and the brake drum have been completely contacted, the S-camshaft torque increases, the big worm relatively compresses the spiral spring to make the taper clutch disengage, and the small worm wheel enters the unloading idle state;

[0014] Step 4: the self-adjusting arm continues to rotate counterclockwise through the elastic deformation angle E, and due to the meshing of the gear and the control disc, the self-rotation of the gear drives the meshed tine clutch associated with it to rotate, the small worm gear is unloaded, the tine clutch drives the small worm to rotate, thereby driving the ratchet wheel associated with the small worm to rotate, so that the ratchet wheel and the pawl rotate synchronously to avoid the pawl and the ratchet wheel being out of position;

[0015] II. In the process of releasing the brake, at most only one effective tooth groove is adjusted:

[0016] Step 5: after the driver releases the brake pedal, the self-adjusting arm rotates clockwise, reverses through the elastic deformation angle E, and the gear and the ratchet wheel remain synchronous rotation due to the action of the tine clutch, which eliminates the influence of elastic deformation on gap adjustment; then the taper clutch between the large worm and the small worm engages;

[0017] Step 6: the self-adjusting arm continues to rotate clockwise, rotates through the difference between Ce and Ce', the pawl rotates relative to the ratchet wheel, and the pawl passes through the ratchet wheel cover and can only fall into the tooth groove B;

[0018] Step 7: the self-adjusting arm continues to rotate clockwise, rotates through Ce' + C, and returns to the original position, the pawl pushes the tooth groove B on the ratchet wheel to reverse to the original tooth groove A position, that is, the ratchet wheel rotates through a tooth interval angle θ of a ratchet tooth, the ratchet wheel drives the small worm to rotate, the small worm drives the small worm gear to rotate, the small worm gear drives the large worm to rotate, the large worm drives the large worm gear to rotate, and the large worm gear drives the S-camshaft to rotate through a corresponding angle, and the gap is adjusted once, Y' = fθ.

[0019] The technical scheme of the present application has the following beneficial effects:

[0020] No matter how large the excess gap (Ce) is, the ratchet wheel cover limits the number of effective tooth grooves that the pawl rotates relative to the ratchet wheel to one tooth groove during each brake return, replacing the current adjustment method of rotating through multiple saw-shaped teeth each time the brake is applied. When the brake is released each time, the pawl drives the ratchet wheel to rotate through a tooth interval angle θ of a ratchet tooth, and drives the large worm gear to rotate through a corresponding angle. The adjustment amount Y' of the self-adjusting arm is fnθ (n = 1), so that Y' is much smaller than Y, and over-adjustment can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present application, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 It is a schematic diagram of the existing automobile brake gap saw-shaped tooth type self-adjusting arm.

[0023] Figure 2 Exploded first perspective view of the self-adjusting arm of the present invention;

[0024] Figure 3 Exploded second perspective view of the self-adjusting arm of the present invention;

[0025] Figure 4 Left side sectional view of the self-adjusting arm of the present invention;

[0026] Figure 5 A enlarged schematic view of part A of the present invention; Figure 3

[0027] Figure 6 Planar perspective view of the self-adjusting arm of the present invention;

[0028] Figure 7 Diagram of the position relationship of the gear, ratchet and pawl of the present invention;

[0029] Figure 8 Schematic diagram of the ratchet cover of the present invention;

[0030] Figure 9 Schematic diagram of the initial state of the self-adjusting arm of the present invention and the corresponding pawl position;

[0031] Figure 10 Schematic diagram of the self-adjusting arm of the present invention when it turns through the reserved clearance angle C during braking of the automobile;

[0032] Figure 11 Schematic diagram of the self-adjusting arm of the present invention when it turns through the angle C+Ce' during braking of the automobile;

[0033] Figure 12 Schematic diagram of the self-adjusting arm of the present invention when it turns through the angle C+Ce'+ (Ce-Ce') during braking of the automobile;

[0034] Figure 13 Schematic diagram of the self-adjusting arm of the present invention when it turns through the angle C+Ce'+ (Ce-Ce')+E during braking of the automobile;

[0035] Figure 14 Schematic diagram of the self-adjusting arm of the present invention when it turns through E during the return stroke after release of the brake of the automobile;

[0036] Figure 15 Schematic diagram of the self-adjusting arm of the present invention when it turns through E+(Ce-Ce') during the return stroke after release of the brake of the automobile;

[0037] Figure 16 Schematic diagram of the self-adjusting arm of the present invention when it turns through E+(Ce-Ce')+Ce'+C during the return stroke after release of the brake of the automobile.

[0038] ​Explanation of reference numerals: 1, housing; 2, large worm; 3, large worm wheel; 4, control disc; 41, gear tooth; 5, gear; 52, groove; 6, small worm; 7, small worm wheel; 8, conical clutch; 9, pointed tooth clutch; 10, small shaft; 11, ratchet wheel; 12, ratchet wheel cover; 121, notch; 13, pawl; 14, control arm; 91, left half clutch; 92, right half clutch; 15, bushing; 17, ratchet tooth; 18, tooth groove; 20, tooth groove A; 21, tooth groove B; 22, spiral spring; 24, leaf spring. DETAILED DESCRIPTION

[0039] The technical solutions of the present application will be described below with reference to the drawings. Obviously, the described embodiments are only a part of the present application, rather than all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0040] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or components referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0041] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0042] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0043] The gap adjustment idea of the present application is:

[0044] No matter how large the excess gap angle Ce is, the pawl only passes through one effective tooth groove each time the brake is applied, and the return adjustment is only based on the tooth gap of one ratchet tooth, and no longer adjusts multiple tooth grooves, that is, no longer depends on Ce, so as to obtain the ideal smaller adjustment amount: Y´=fθ.

[0045] II. The self-adjusting arm can make the pawl pass through the angle θ of the effective tooth gap of the ratchet wheel and also turn through the difference between Ce and Ce' when braking, until the brake drum and the brake shoe are fully contacted and the braking action is completed.

[0046] III. The subsequent elastic deformation cannot affect the clearance adjustment.

[0047] We call the clearance adjustment method satisfying the three conditions as "fixed value method", and it is obvious that the adjustment amount of the fixed value method is much smaller than that of the extreme value method.

[0048] The present application provides a kind of automobile brake clearance ratchet type fixed value self-adjusting arm, as shown in Figures 2-8 The initial state of the self-adjusting arm is deviated from the perpendicular bisector of the camshaft by an angle C, the central axis of the self-adjusting arm coincides with the 0° reference line, and the pawl 13 is located in the tooth groove A20.

[0049] The small worm wheel 7 is coaxially arranged with the large worm 2, the pointed tooth clutch 9 includes a left half clutch 91 and a right half clutch 92, the left half clutch 91 and the right half clutch 92 can be engaged, the small worm 6, the left half clutch 91, the right half clutch 92 and the ratchet wheel 11 are sleeved on the small shaft 10, the small worm 6, the bushing 15, the ratchet wheel 11 and the left half clutch 91 are fixedly connected, the right half clutch 91 is axially slidably connected with the gear 5, the control disc 4 is provided with a plurality of teeth 41 on a part of the outer periphery, the gear 5 is engaged with the teeth 41, and the gear 5 rotates in the hole of the shell 1 when the self-adjusting arm rotates. The ratchet wheel cover 12 is fixedly connected with the shell 1, the ratchet wheel cover 12 is provided with three notches 121 corresponding to the three pawls, the front surface of the gear 5 is provided with three recesses 52, each recess 52 is hingedly connected with one end of a pawl 13, the other end of the pawl 13 is tightly attached to the surface of the ratchet wheel 11 or the ratchet wheel cover 12 under the action of the leaf spring 24, the small worm 6 is engaged with the small worm wheel 7, and the large worm 2 and the small worm wheel 7 are connected by the conical clutch 8. When the conical clutch 8 is disengaged, the small worm wheel 7 idles, and when the conical clutch 8 is engaged, the small worm wheel 7 rotates with the large worm 2 and the large worm wheel 3.

[0050] As shown in Figure 9 The initial state of the self-adjusting arm is deviated from the perpendicular bisector of the camshaft by an angle C, the central axis of the self-adjusting arm coincides with the 0° reference line, and the pawl 13 is located in the tooth groove A20.

[0051] When the automobile needs to brake, the driver steps on the brake pedal, the brake chamber push rod pushes the self-adjusting arm to rotate counterclockwise at the center of the control disc 4, and the control disc 4 is fixedly connected with the car body and is fixed, becoming the rotation center of the self-adjusting arm. At this time, there are two cases:

[0052] 1. If the actual gap of the hoof drum is less than or equal to the reserved gap ζ, correspondingly, when the actual rotation angle of the self-adjusting arm is less than or equal to the reserved gap angle C, the self-adjusting arm rotates counterclockwise, rotating through angle C, and then through the elastic deformation angle E; when the pedal is released, the elastic deformation angle is released first, and then it rotates freely through angle C, returning to the original position. During this process, the pawl 13 only moves back and forth within the tooth groove 20 of the initial position, without skipping a tooth groove. When the self-adjusting arm returns, the ratchet 11 will not rotate, and the gap of the hoof drum will not be adjusted. (Elastic deformation here is not analyzed);

[0053] 2. If the actual gap of the drum is greater than the reserved gap ζ, and correspondingly, the actual rotation angle of the self-adjusting arm is greater than the reserved gap angle C, the adjustment mechanism of the self-adjusting arm will reduce the angle of the self-adjusting arm. The adjustment steps are as follows:

[0054] ① Record the basis for adjustment during braking:

[0055] Step 1: As Figure 10 As shown, when the driver presses the brake pedal, the self-adjusting arm rotates counterclockwise. When it rotates past the reserved clearance angle C, the brake shoes open. Since the actual clearance between the brake shoes and the brake drum is greater than the reserved clearance ζ, the brake shoes and the brake drum do not make full contact. When the self-adjusting arm is rotating, because the gear 5 meshes with the control disc 4, the gear 5 rotates, causing the pawl 13 to rotate relative to the ratchet 11. The pawl 13 rotates from the tooth groove A20 through an angle equivalent to C and reaches a certain point on the upper part of the tooth groove A20.

[0056] Step 2: As Figure 11 As shown, the self-adjusting arm continues to rotate counterclockwise. When it rotates through the angle Ce´, the pawl 13 falls from a certain point on the upper part of the tooth groove A20 into the tooth groove B21. The brake shoe and the brake drum have not yet made full contact.

[0057] Step 3: As Figure 12 As shown, the self-adjusting arm continues to rotate counterclockwise. When it passes Ce-Ce´, the pawl 13 may still be rotating within the tooth groove B21, or it may have already passed the notch 121 of the ratchet cover 12 and been lifted by the outer circumferential surface of the ratchet cover 12. If the temperature is high and thermal expansion occurs during this stage, the shoe-drum clearance will increase, and the rotation angle of the self-adjusting arm will also increase accordingly. However, during the return adjustment, the pawl 13 still only rotates through one effective tooth groove. At this time, the brake shoe and brake drum are in complete contact, the S-camshaft torque increases, the large worm gear 2 relatively compresses the coil spring 22 to disengage the conical clutch 8, and the small worm gear 7 enters the unloaded idling state;

[0058] Step 4: As Figure 13As shown, the self-adjusting arm continues to rotate counterclockwise, passing through the elastic deformation angle E. The gear 5 meshes with the control disk 4. When the gear 5 rotates, it drives the already meshed sharp-tooth clutch 9 that is slidingly connected to it to rotate. The small worm gear 7 is unloaded. The sharp-tooth clutch 9 drives the small worm 6 and the sleeve 15 to rotate, thereby driving the ratchet 11 that is keyed to the sleeve 15 to rotate. The ratchet 11 and the pawl 13 rotate synchronously, avoiding the pawl 13 and the ratchet 11 from being out of place.

[0059] ② During the release of the brake, adjust the shoe drum clearance according to the effective tooth groove of pawl 13 as recorded during the braking process.

[0060] Step 5: As Figure 14 As shown, after the driver releases the brake pedal, the self-adjusting arm rotates clockwise, reversing the elastic deformation angle E. Due to the action of the toothed clutch 9, the pawl 13 and ratchet 11 maintain synchronous rotation, thus eliminating the influence of elastic deformation on clearance adjustment. At this time, the conical clutch 8 between the large worm gear 2 and the small worm wheel 7 engages.

[0061] Step 6: As Figure 15 As shown, the self-adjusting arm continues to rotate clockwise, then rotates back to the difference between Ce and Ce´, the pawl 13 rotates relative to the ratchet 11, passes over the notch of the ratchet cover 12, and falls into the tooth groove B21;

[0062] Step 7: As Figure 16 As shown, the self-adjusting arm continues to rotate clockwise, passing Ce´+C, and returns to its original position. The pawl 13 pushes the tooth groove B21 on the ratchet 11 to rotate back to the original tooth groove A20 position, that is, the ratchet 11 rotates through the tooth angle θ of the ratchet 17. The ratchet drives the small worm 6 to rotate, the small worm 6 drives the small worm wheel 7 to rotate, the small worm wheel 7 drives the large worm 2 to rotate, the large worm 2 drives the large worm wheel 3 to rotate, and the large worm wheel 3 drives the S-camshaft to rotate through a corresponding angle, and the clearance is adjusted once, Y´=fθ.

[0063] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A ratchet-type self-adjusting brake clearance for automobiles, comprising a housing (1) and a large worm gear (2), a large worm wheel (3), a control disc (4), a gear (5), a small worm gear (6), a small worm wheel (7), a conical clutch (8), a pointed tooth clutch (9), and a small shaft (10) disposed within the housing (1). The control disc (4) is fixedly connected to the control arm (14), and the control arm (14) is fixed to the vehicle body. The housing (1) is rotatable relative to the control disc (4), and the gear (5) is rotatable within the housing (1). The gear (5) is connected to the control disc (10). The disc (4) is engaged, the pointed tooth clutch (9) includes a left half clutch (91) and a right half clutch (92), the left half clutch (91) and the right half clutch (92) are engageable, the left half clutch (91) is fixedly connected to the small worm (6), the right half clutch (92) is axially slidably connected to the gear (5), the small worm (6) is engaged with the small worm wheel (7), the large worm (2) and the small worm wheel (7) are connected by the conical clutch (8), the large worm (2) is engaged with the large worm wheel (3), characterized in that, It also includes a ratchet (11), a ratchet cover (12), and a pawl (13). The ratchet (11) is keyed to the small worm (6). The ratchet cover (12) is fixedly connected to the housing (1). The ratchet cover (12) has three notches (121). The front of the gear (5) has three grooves (52). Each groove (52) is hinged to one end of a pawl (13). The other end of the pawl (13) is pressed against the surface of the ratchet cover (12) or across the notch (121) and pressed against the surface of the ratchet (11) under the action of the leaf spring (24).

2. The method for adjusting a ratchet-type self-adjusting arm for adjusting automotive brake clearance as described in claim 1, characterized in that, The process includes the following: After the self-adjusting arm is installed, its initial state is that the vertical line of the S-camshaft is deviated to the right by an angle C, and the centerline of the self-adjusting arm coincides with the 0° reference line. I. Record the adjustment basis during braking – skip only one valid tooth groove: Step 1: When the driver presses the brake pedal, the self-adjusting arm rotates counterclockwise. When it rotates past the reserved clearance angle C, the brake shoe and the brake drum are not in complete contact. The gear (5) rotates, causing the pawl (13) to rotate relative to the ratchet (11). The pawl (13) rotates from the tooth groove A (20) through an angle equivalent to C and reaches a certain point on the upper part of the tooth groove A (20). Step 2: The self-adjusting arm continues to rotate counterclockwise. When it rotates through the angle Ce´, the pawl (13) falls into the tooth groove B (21). The brake shoe and the brake drum have not yet made full contact. Step 3: The self-adjusting arm continues to rotate counterclockwise. When it passes the difference between Ce and Ce´, the pawl (13) may still be rotating in the tooth groove B (21), or it may pass the notch (121) of the ratchet cover (12) and be lifted by the outer circumferential surface of the ratchet cover (12). At this time, since the brake shoe and the brake drum are in complete contact, the torque of the S-camshaft increases, and the large worm gear (2) relatively compresses the helical spring (22) to disengage the conical clutch (8), and the small worm gear (7) enters the unloaded idling state. Step 4: The self-adjusting arm continues to rotate counterclockwise, passing through the elastic deformation angle E. Since the gear (5) meshes with the control disk (4), the gear (5) rotates and drives the already meshed sharp tooth clutch (9) that slides with it to rotate. The small worm wheel (7) has been unloaded. The sharp tooth clutch (9) drives the small worm (6) to rotate, thereby driving the ratchet (11) that is fixed to the small worm (6) to rotate. Thus, the ratchet (11) and the pawl (13) rotate synchronously to avoid the pawl (13) and the ratchet (11) from being out of place. II. During the brake release process, only one effective tooth groove can be adjusted at most: Step 5: After the driver releases the brake pedal, the self-adjusting arm rotates clockwise and reverses through the elastic deformation angle E. Due to the action of the sharp tooth clutch (9), the gear (5) and ratchet (11) maintain synchronous rotation, which eliminates the influence of elastic deformation on the clearance adjustment. Then the conical clutch (8) between the large worm (2) and the small worm (7) re-engages. Step 6: The self-adjusting arm continues to rotate clockwise, and then rotates back to the difference between Ce and Ce´. The pawl (13) rotates relative to the ratchet (11). The pawl (13) passes over the ratchet cover (12) and can only fall into the tooth groove B (21). Step 7: The self-adjusting arm continues to rotate clockwise, passing Ce´+C, and returns to its original position. The pawl (13) pushes the tooth groove B (21) to reverse to the original tooth groove A (20) position, that is, the ratchet (11) rotates through the tooth angle θ of one ratchet tooth (17). The ratchet (11) drives the small worm (6) to rotate, the small worm (6) drives the small worm wheel (7) to rotate, the small worm wheel (7) drives the large worm (2) to rotate, the large worm (2) drives the large worm wheel (3) to rotate, and the large worm wheel (3) drives the S-camshaft to rotate through a corresponding angle, and the clearance is adjusted once, Y´=fθ.

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