CN112528395B - Gasoline engine torsional vibration damper fixing bolt type selection and checking method - Google Patents
Gasoline engine torsional vibration damper fixing bolt type selection and checking method Download PDFInfo
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- CN112528395B CN112528395B CN202011241906.4A CN202011241906A CN112528395B CN 112528395 B CN112528395 B CN 112528395B CN 202011241906 A CN202011241906 A CN 202011241906A CN 112528395 B CN112528395 B CN 112528395B
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- G06—COMPUTING; CALCULATING OR COUNTING
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- G06F30/10—Geometric CAD
- G06F30/15—Vehicle, aircraft or watercraft design
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
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- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Abstract
The invention relates to a gasoline engine torsional vibration damper fixing bolt type selection and checking method, which belongs to the technical field of vehicle manufacturing. The method can accurately carry out forward type selection on the fastening bolt of the torsional vibration damper, is simple and easy to understand, is more perfect in consideration, and the selected bolt is more in line with the actual use condition.
Description
Technical Field
The invention belongs to the technical field of vehicle manufacturing, and particularly relates to a method for selecting and checking a fixing bolt of a torsional vibration damper of a gasoline engine.
Background
In the transmission system of the gasoline engine, a bolt for fixing the torsional vibration damper sequentially penetrates through a gasket, the torsional vibration damper, a signal disc, a timing chain wheel and an oil pump chain wheel and then is screwed on the end face of the crankshaft, the torsional vibration damper, the signal disc, the timing chain wheel and the oil pump chain wheel are tightly pressed on the end face of the crankshaft through pretightening force applied by the bolt, and relative sliding between the parts is prevented by means of friction force between contact surfaces. When the engine runs, the torsional vibration damper, the timing chain wheel and the oil pump chain wheel respectively output torque outwards so as to ensure the normal running of engine parts such as a water pump system, an accessory system, a gas distribution mechanism, an oil pump and the like. The fixing bolt of the torsional vibration damper has enough strength and hardness to overcome the alternating output torque load, otherwise the torsional vibration damper is easy to loosen, the gas distribution timing is staggered, the oil pump does not work, and even the engine is damaged. The torsional vibration damper fixing bolt belongs to the key parts of the engine.
However, in the prior art, the design method of the fixing bolt of the torsional vibration damper is not perfect, so that the fixing bolt of the torsional vibration damper has safety risk in the using process.
Disclosure of Invention
The invention provides a gasoline engine torsional vibration damper fixing bolt type selection and checking method, which is used for solving the technical problem that safety risks exist in the use process due to the fact that the design method of the torsional vibration damper fixing bolt in the prior art is incomplete.
The invention is realized by the following technical scheme: a gasoline engine torsional vibration damper fixing bolt type selection and checking method comprises the following steps:
obtaining the equivalent contact radius of each joint surface according to the contact outer diameter and the contact inner diameter of each joint surface;
obtaining the anti-sliding torque of each joint surface according to the equivalent contact radius of each joint surface and the preset pretightening force of the bolt;
obtaining the minimum anti-slip torque of the system according to the anti-slip torque of each joint surface;
obtaining the maximum driving torque of a system, comparing the minimum anti-slip torque of the system with the maximum driving torque of the system, and confirming that the preset pretightening force of the bolt is qualified when the minimum anti-slip torque of the system is larger than the maximum driving torque of the system;
obtaining the pretightening force required by the bolt to fasten the torsional vibration damper according to the preset pretightening force and the preset safety factor of the bolt;
preliminarily selecting the type of the bolt according to the bolt assembly boundary condition and a pretightening force required by the bolt to fasten the torsional vibration damper;
in a mass production state of the combined bolts, the parameters of the bolts in multiple batches have dispersion, the actual minimum pretightening force of the bolt is obtained according to the minimum yield strength and the maximum friction coefficient of the bolt corresponding to the selected bolt model, and the actual maximum pretightening force of the bolt is obtained according to the maximum yield strength and the minimum friction coefficient of the bolt;
obtaining an actual safety factor of the bolt according to the actual minimum pretightening force of the bolt and the preset pretightening force of the bolt, and comparing the actual safety factor with the preset safety factor;
obtaining the contact stress of each joint surface according to the actual maximum pretightening force of the bolt and the contact area of each joint surface, and comparing the contact stress of each joint surface with the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface;
and when the actual safety factor is larger than the preset safety factor and the contact stress of each joint surface is smaller than the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, determining that the selected bolt model is qualified.
Further, in order to better implement the present invention, the equivalent contact radius of each joint surface is obtained according to the contact outer diameter and the contact inner diameter of each joint surface, specifically:
equivalent contact radius per bonding surface
Said R is0For each joint faceCorresponding contact outer diameter, said RiFor each interface surface.
4. Further, in order to better implement the present invention, the obtaining of the anti-sliding torque of each joint surface according to the equivalent contact radius of each contact surface and the predetermined pre-tightening force of the bolt specifically includes:
the anti-slip torque M of each joint surfacei＝μ×Fx×ReiThe coefficient of friction of each bonding surface is mu, FxA predetermined pretension force for the bolt.
Further, in order to better implement the present invention, the minimum anti-slip torque of the system is obtained according to the anti-slip torque of each joint surface, specifically:
minimum anti-slip torque of the system:
Ms＝min(M1+M2，M2+M3，M3+M4，M4+M5，M5+M6)；
said M1The anti-slippage torque is the combined surface between the bolt head and the gasket;
the M is2The anti-slip torque of the joint surface between the gasket and the torsional vibration damper;
the M is3The anti-slip torque is the anti-slip torque of the junction surface between the torsional vibration damper and the signal panel;
the M is4The anti-slippage torque is the combined surface between the signal panel and the timing chain wheel;
the M is5The anti-slip torque of the joint surface between the timing chain wheel and the oil pump chain wheel is obtained;
the M is6The anti-slip torque of the joint surface between the oil pump chain wheel and the crankshaft.
Further, in order to better implement the present invention, the maximum driving torque of the system is obtained, specifically:
maximum driving torque M of the systema＝Me1+Me2+Me3；
Said Me1A maximum torque transmitted for said torsional vibration damper;
the M ise2A maximum torque transmitted for the timing sprocket;
the M ise3The maximum torque is transmitted to the oil pump chain wheel.
Further, in order to better implement the present invention, the pre-tightening force required by the bolt to fasten the torsional vibration damper is obtained according to the pre-tightening force of the bolt and a pre-determined safety factor, specifically:
the bolt fastens the torsional vibration damper to provide pretightening force Fv＝K×FxAnd K is the preset safety factor.
Further, in order to better implement the present invention, the obtaining of the actual minimum pre-tightening force of the bolt according to the minimum yield strength and the maximum friction coefficient of the bolt corresponding to the selected bolt model includes: actual minimum pretension of the bolt
The actual maximum pretightening force of the bolt is obtained according to the maximum yield strength and the minimum friction coefficient of the bolt, and the method specifically comprises the following steps:
actual maximum pre-tightening force of the bolt
V is a yield strength utilization coefficient of the bolt, RP0.2maxIs the maximum yield strength of the bolt, said RP0.2minIs the minimum yield strength of the bolt, said AsIs the nominal stress cross-sectional area of the external thread of the bolt, d2Is the pitch diameter of the thread of the bolt, d0Is the nominal stress cross-sectional area equivalent diameter of the external thread of the bolt, the alpha' is the thread flank angle of the bolt, the musminIs the minimum coefficient of friction of the bolt thread, musmaxIs the most threaded of the boltAnd the large friction coefficient is large, and P is the thread pitch of the bolt.
Further, in order to better implement the present invention, the obtaining an actual safety factor of the bolt according to the actual minimum pretightening force of the bolt and the predetermined pretightening force of the bolt specifically includes:
actual safety factor of the bolt
Further, in order to better implement the present invention, the obtaining of the contact stress of each joint surface according to the actual maximum pretightening force of the bolt and the contact area of each joint surface specifically includes:
contact stress of each bonding surface
A is describedi＝π×(R0 2-Ri 2)。
Further, to better implement the present invention, the above method is performed in the EXCEL form.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a method for selecting and checking a fixed bolt of a torsional vibration damper of a gasoline engine, which comprises the steps of firstly obtaining an equivalent contact radius of each joint surface according to the contact outer diameter and the contact inner diameter of each joint surface, then setting a preset pretightening force for the bolt for fixing the torsional vibration damper, combining the equivalent contact radius of each joint surface with the preset pretightening force of the bolt to calculate the anti-sliding torque of each joint surface, calculating the minimum anti-sliding torque of the whole system according to the anti-sliding torque of each joint surface, comparing the minimum anti-sliding torque of the whole system with the maximum driving torque of the whole system, judging that the preset pretightening force of the bolt is qualified when the minimum anti-sliding torque of the system is greater than the maximum driving torque of the system, simplifying the design and calculation of the bolt for fixing the torsional vibration damper, facilitating understanding, reserving the safety margin of the bolt, combining the axial force attenuation in the using process of the bolt to determine the preset safety factor which the bolt needs to be provided by the torsional vibration damper, calculating the pretightening force of the torsional vibration damper to ensure that the bolt needs to be fastened according to the minimum pretightening force required by the obtained bolt, and the actual working factor of the selected bolt, and the maximum pretightening force of the selected bolt, and the blind fastening efficiency of the selected bolt, and the blind bolt, and the maximum pretightening force of the selected bolt, and the blind bolt, and the bolt The method comprises the steps of obtaining the contact stress of each joint surface by utilizing the actual maximum pre-tightening force of a selected bolt and the contact area of each joint surface, comparing the actual safety factor of the selected bolt with the estimated safety factor, re-selecting the bolt when the actual safety factor is smaller than or equal to the estimated safety factor, comparing the contact stress of each joint surface with the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, and re-selecting the bolt when the contact stress of each joint surface is larger than or equal to the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a flow chart of a gasoline engine torsional vibration damper fixing bolt sizing and checking method herein;
FIG. 2 is a schematic illustration of an assembled configuration of a torsional vibration damper and chain drive system of the present application;
FIG. 3 is a schematic view of the assembly of the torsional damper fixing bolt of the present application;
FIG. 4 is a table illustrating an example of the process of determining the pretension required to provide by a bolt to tighten a torsional vibration damper according to the present application;
FIG. 5 is a table illustrating exemplary bolt sizing and actual maximum pretension and actual minimum pretension calculation processes in the present application;
fig. 6 is a table showing an example of the bolt checking process in the present application.
In the figure:
1-a bolt; 2-torsional vibration damper; 3-a timing chain drive system; 4-oil pump chain drive system; 5-an oil pump; 6-a camshaft; 7-a crankshaft; 8-a piston; 9-signal panel; 10-a timing sprocket; 11-oil pump chain wheel.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
Example 1:
the embodiment provides a method for selecting and checking a fixing bolt of a torsional vibration damper of a gasoline engine, which is used for solving the technical problem of safety risk in the use process caused by the incomplete design method of the fixing bolt of the torsional vibration damper in the prior art. Specifically, in the existing method for designing the fixing bolt of the torsional vibration damper, the actual conditions of the friction coefficient dispersion, the yield strength dispersion, the specification, the size and the like of the bolt are not considered, and most of the bolts with different specifications are selected in a trial and error mode during model selection, so that the pretightening force of the selected bolt can not meet the requirement due to the reasons, and the model selection and the checking process are complex and easy to make mistakes, so that the selected bolt has a greater safety risk during use.
As shown in fig. 2 and 3, the bolt 1 for fixing the torsional vibration damper 2 is mainly used for fastening the torsional vibration damper 2, the timing sprocket 10 of the timing chain drive system 3, the oil pump sprocket 11 of the oil pump chain drive system 4 (including the oil pump 5), the signal disc 9, and the crankshaft 7. When the engine runs, the work done by the combustion stroke is converted into torque through a component formed by the piston 8 and the connecting rod, and the torque is transmitted to the crankshaft 7 and the torsional vibration damper 2 and is output to a cooling and accessory system; meanwhile, the timing chain driving system 3 drives the timing chain to drive one camshaft 6 to operate through a timing chain wheel 10 arranged on a crankshaft 7; the oil pump 4 drives the oil pump chain to rotate by an oil pump chain drive operation 4 also mounted on the crankshaft 7, which drives the other camshaft 6 to rotate, and the three drive systems transmit drive torque by static friction force generated between the joint surfaces. Along with the real-time change of the operation condition of the engine, the driving torque of each system fluctuates in real time. By applying a proper and uniform axial force to the bolt 1 for fixing the torsional vibration damper, the relative rotation of each driving system can be ensured when the driving systems operate.
Referring to fig. 3, a bolt 1 is screwed to the end face of the crankshaft 7 after passing through a gasket, a torsional vibration damper 2, a signal disc 9, a timing sprocket 10 and an oil pump sprocket 11 in sequence, the torsional vibration damper 2, the signal disc 9, the timing sprocket 10 and the oil pump sprocket 11 are pressed against the end face of the crankshaft 7 by a pretightening force applied by the bolt 1, and relative slippage between the components is prevented by a frictional force between contact surfaces.
The application provides a gasoline engine torsional vibration damper fixing bolt type selection and checking method which comprises the following steps:
step 1.1: obtaining an equivalent contact radius per bonding surface from the outer and inner contact diameters of each bonding surface, specifically, the equivalent contact radius per surface
Wherein R is0For each corresponding contact external diameter of the faying surface, RiFor each interface surface. The method comprises the following specific steps:
the joint surface between the head of the bolt 1 and the gasket is a first surface, and the contact outer diameter of the first surface is R01The contact inner diameter of the first face is R1The equivalent contact radius of the first face is
The joint surface of the gasket and the torsional vibration damper 2 is a second surface, and the contact outer diameter of the second surface is R02The contact inner diameter of the second face is R2The equivalent contact radius of the second face is
The joint surface between the torsional vibration damper 2 and the signal panel 9 is a third surface, and the contact outer diameter of the third surface is R03The contact inner diameter of the third surface is R3The equivalent contact radius of the third surface is
The combining surface between the signal panel 9 and the timing chain wheel 10 is a fourth surface, and the contact outer diameter of the fourth surface is R04The contact inner diameter of the fourth face is R4The equivalent contact radius of the fourth face is
The joint surface between the timing chain wheel 10 and the oil pump chain wheel 11 is a fifth surface, and the contact outer diameter of the fifth surface is R05The contact inner diameter of the fifth surface is R5The equivalent contact radius of the fifth surface is
The joint surface between the oil pump chain wheel 11 and the end surface of the crankshaft 7 is a sixth surface, and the contact outer diameter of the sixth surface is R06The sixth contact inner diameter is R6The equivalent contact radius of the sixth surface is
Step 1.2: presetting a predetermined pretension force F for a screw 1 for fastening a torsional vibration damper 2xIn the present embodiment, the friction coefficient of each joint surface is the same as mu according to the equivalent contact radius of each joint surface and the friction coefficient between the joint surfaces, and the anti-slip torque M of each joint surface is calculated therefromi＝μ×Fx×Rei(formula 2). The method comprises the following specific steps:
the first surface has an anti-slip torque of M1＝μ×Fx×Re1；
The second surface has an anti-slip torque of M2＝μ×Fx×Re2；
The third surface has an anti-slip torque of M3＝μ×Fx×Re3；
The fourth surface has an anti-slip torque of M4＝μ×Fx×Re4；
The fifth surface has an anti-slip torque of M5＝μ×Fx×Re5；
The sixth surface has an anti-slip torque of M6＝μ×Fx×Re6。
Step 1.3: obtaining a minimum anti-slip torque M of the system according to the anti-slip torque of each joint surfaces。
Because two sides of the gasket are respectively connected with the screwThe bolt 1 is connected with the torsional vibration damper 2, so that the anti-sliding torque of the gasket is the sum of the anti-sliding torque of the first surface and the anti-sliding torque of the second surface, namely the anti-sliding torque of the gasket is M1+M2；
Because the two sides of the torsional vibration damper 2 are respectively connected with the gasket and the signal panel 9, the anti-sliding torque of the torsional vibration damper 2 is the sum of the anti-sliding torque of the second surface and the anti-sliding torque of the third surface, namely the anti-sliding torque of the torsional vibration damper 2 is M2+M3；
Because the two sides of the signal panel 9 are respectively connected with the torsional vibration damper 2 and the timing chain wheel 10, the anti-slip torque of the signal panel 9 is the sum of the third surface anti-slip torque and the fourth surface anti-slip torque, namely the anti-slip torque of the signal panel 9 is M3+M4；
Since both sides of the timing sprocket 10 are respectively connected to the signal plate 9 and the engine oil pump sprocket 11, the anti-slip torque of the timing sprocket 10 is the sum of the anti-slip torque of the fourth surface and the anti-slip torque of the fifth surface, that is, the anti-slip torque of the timing sprocket 10 is M4+M5；
Since both sides of the engine oil pump sprocket 11 are respectively connected to the timing sprocket 10 and the crankshaft 7, the anti-slip torque of the engine oil pump sprocket 11 is the sum of the anti-slip torque of the fifth surface and the anti-slip torque of the sixth surface, that is, the anti-slip torque of the engine oil pump sprocket 11 is M5+M6。
Therefore the minimum anti-slip torque of the system:
Ms＝min(M1+M2，M2+M3，M3+M4，M4+M5，M5+M6) (formula 3);
it is worth noting that the system is a transmission system fastened by bolts 1 and composed of a gasket, a torsional vibration damper 2, a signal disc 9, a timing chain drive system 3, an engine oil chain drive system 4 and a crankshaft 7, and the minimum anti-slip torque M of the system issOn one of the components, i.e. the one with the worst resistance to slip in the system.
Step 1.4: the essence of the system is to transmit torque, wherein the torsional vibration damper 2, the timing sprocket 10 and the engine oil sprocket 11 transmit different torques to different execution systems, and the maximum torque transmitted by the torsional vibration damper 2 is limited to be Me1The maximum torque transmitted by the timing sprocket 10 is Me2The maximum torque transmitted by the oil pump chain wheel 11 is Me3Thus, the maximum drive torque (i.e. the total torque transmitted by the system) M of the systema＝Me1+Me2+Me3(formula 4).
Minimum anti-slip torque M of systemsMaximum driving torque M of systemaThe comparison is made, at minimum anti-slip torque M of the systemsGreater than the maximum drive torque M of the systemaIn the process, the preset pretightening force of the bolt 1 can be determined to be qualified, and the minimum anti-sliding torque M of the system is obtainedsMaximum driving torque M of less than or equal to the systemaAnd if so, judging that the preset pretightening force of the bolt 1 is unqualified, and returning to the step 1.2 to preset the preset pretightening force for the bolt 1 again.
Step 1.5: because the connecting system of the bolt 1 fixed by the torsional vibration damper 2 has a plurality of joint surfaces, each joint surface has microscopic unevenness and roughness, the bolt 1 deforms microscopically after being pre-tightened, in addition, when an engine runs for a long time, the friction coefficient of each joint surface is reduced due to contact abrasion, and due to long-time mechanical and cold-hot alternating load, the material creep thinning of a connected piece is caused to cause larger axial force attenuation of the bolt 1, in order to ensure that the bolt 1 can still keep fastening under the condition of axial force attenuation, a preset safety coefficient K is preset for the bolt 11, and the preset pre-tightening force for the bolt 1 is combined, so that the pre-tightening force F required by the fastening of the torsional vibration damper 2 by the bolt 1 can be obtainedv＝K×Fx(formula 5), that is, the bolt 1 needs to be applied with at least FvThis pretensioning force can only cause the torsional vibration damper 2 to be fastened to the crankshaft 7 and to press the signal disk 9, the timing sprocket 10 and the pump sprocket 11. Thus, by setting the safety coefficient K in consideration of the attenuation of the axial force of the bolt 1 in the use process, the bolt 1 can ensure that the pre-tightening force for fastening the torsional vibration damper 2 is more compliant, the type selection of the bolt 1 is more accurate,but also leaves a sufficient safety margin. As a best mode for this embodiment, the value of K in this embodiment is 2.0.
It is noted that the bolts 1 in step 1.1 to step 1.5 correspond to the bolts assumed to meet the assembly requirements.
Step 2.1: according to the boundary conditions of the assembly of the bolt 1 on the torsional vibration damper 2 and FvInitially selecting the type of the bolt, wherein the rated minimum pretightening force of the selected bolt 1 is larger than the pretightening force F required by the bolt 1 to fasten the torsional vibration damper 2v。
By passing
Calculating the actual minimum pretightening force of the bolt 1, wherein v in the formula 6 is the yield strength utilization coefficient of the bolt 1, and RP0.2minIs the minimum yield strength of the bolt 1, AsIs the nominal stress cross-sectional area, d, of the external thread of the bolt 12Is the pitch diameter of the thread of the bolt 1, d0Is the nominal stress cross-sectional area equivalent diameter of the external thread of the bolt 1, alpha' is the thread flank angle of the bolt 1, musmaxIs the maximum coefficient of friction of the thread of the bolt 1 and P is the pitch of the bolt 1. In the step, firstly, the specification and the size of the bolt 1 are determined according to an assembly boundary, namely, the bolt 1 is subjected to forward type selection, blind type selection among various types of bolts is avoided, the working efficiency is improved, and then the actual minimum pretightening force of the selected bolt 1 is calculated through a formula 6 and is matched with the actual minimum pretightening force FvA comparison was made to perform a preliminary model selection of the bolt 1. In this step, the actual minimum tightening force of the bolts 1 is determined more precisely in consideration of the specifications and dimensions, the difference in friction coefficient, the difference in yield strength, and the specific use of the bolts 1 of different batches in mass production.
Step 2.2: according to
Calculating the actual maximum pretension force F of the bolt 1MmaxWhere v in the formula 7 is a yield strength utilization coefficient of the bolt 1, RP0.2maxMaximum yield strength of the bolt 1, AsIs the nominal stress cross-sectional area, d, of the external thread of the bolt 12Is the pitch diameter of the thread of the bolt 1, d0Is the nominal stress cross-sectional area equivalent diameter of the external thread of the bolt 1, alpha' is the thread flank angle of the bolt 1, musminIs the minimum coefficient of friction of the thread of the bolt 1 and P is the pitch of the bolt 1. In consideration of the actual maximum pre-tightening force of the bolt 1, which is determined more precisely according to the specifications and sizes of the bolts 1 of different batches, the dispersion difference of friction coefficients, the dispersion difference of yield strengths and specific use conditions in the mass production state, it should be noted that, in the calculation process of the actual maximum pre-tightening force of the bolt 1, except for R, R isP0.2maxAnd musminExcept for the difference in the calculation of the minimum pretightening force, all other parameters are the same.
It should be noted that in step 2.1 and step 2.2, the maximum yield strength R of the bolt 1 is definedP0.2maxAnd minimum yield strength RP0.2minDepending on the material batch and production process control, R is requiredP0.2maxAnd RP0.2minIs within a specified range, and in one embodiment of this embodiment, R isP0.2maxAnd RP0.2minThe value range of the difference is 100MPa.
In addition, μsmaxAnd musminMainly depending on the bolt 1 surface treatment process. Specifically, when the surface of the bolt 1 is phosphated and then oiled, musmax＝0.14，μsmin=0.08; when the surface of the bolt 1 is blackened, the oil is coated to musmax＝0.16，μsmin＝0.10。
Also, v in the expressions 6 and 7 depends on the specific tightening condition of the bolt 1, and when the bolt 1 is tightened in the elastic region, the yield strength utilization coefficient v of the bolt 1 ranges from 70% to 90%, and most preferably, in this case, the yield strength utilization coefficient v of the bolt 1 is 90%; when the bolt 1 is tightened in the plastic region, the yield strength utilization coefficient v of the bolt 1 ranges from 100% to 110%, and most preferably, the yield strength utilization coefficient v of the bolt 1 is 100%.
Therefore, the method provided by the invention fully considers the axial force attenuation of the bolt 1 in the process of selecting the type of the fixing bolt 1 of the torsional vibration damper 2, and the parameters of the bolt 1 such as the bolt specification, the friction coefficient and the yield strength have dispersion difference among multiple batches in the mass production state of the bolt 1, so that the pretightening force range of the bolt 1 is determined by combining the actual production state when the pretightening force is defined, the type selection of the bolt 1 is more accurate, and the probability of safety problems in the use process of fixing the bolt 1 by the torsional vibration damper 2 is reduced.
Step 3.1: obtaining the actual safety factor of the bolt 1 according to the actual minimum pretightening force of the bolt 1 and the preset pretightening force of the bolt 1
And (3) comparing the actual safety coefficient of the bolt 1 with the preset safety coefficient K of the bolt 1, returning to the step 2.1 to perform model selection on the bolt 1 again when K 'is less than or equal to K, and judging that the model selection of the bolt 1 is qualified when K' is greater than K. In the step, K' must be larger than the value of K but should be as close as possible, otherwise, too much design margin occurs, and material waste is caused.
Step 3.2: obtaining the contact stress of each contact surface according to the actual maximum pretightening force of the bolt 1 and the contact area of each joint surface
Wherein A isi＝π×(R0 2-Ri 2) (formula 10), specifically:
contact stress of the first surface
A1＝π×(R01 2-R1 2)；
Contact stress of the second surface
A2＝π×(R02 2-R2 2)；
Contact stress of the third surface
A3＝π×(R03 2-R3 2)；
Contact stress of the fourth surface
A4＝π×(R04 2-R4 2)；
Contact stress of the fourth surface
A5＝π×(R05 2-R5 2)；
Contact stress of the fourth surface
A6＝π×(R06 2-R6 2)。
And comparing the contact stress of each joint surface with the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, specifically:
since the gasket is in direct contact with the head of the bolt 1, the pressed body on the first surface is the gasket, and the contact stress sigma of the first surface is set to be the contact stress sigma of the first surface1Comparing the allowable contact stress with the manufacturing material of the gasket;
since the torsional damper 2 is pressed in contact with the gasket, the pressed body at the second surface is the torsional damper 2, and the contact stress σ of the second surface is set to be the contact stress σ of the second surface2Comparing with allowable contact stress of the manufacturing material of the torsional vibration damper 2;
since the signal panel 9 is directly pressed in contact with the torsional damper 2, the pressed body on the third surface is the signal panel 9, and the contact stress σ of the third surface is adjusted3Comparing with allowable contact stress of the manufacturing material of the signal disc 3;
since the timing sprocket 10 is directly pressed by contact with the signal panel 9, the pressed body on the fourth surface is the timing sprocket 10, and the contact stress σ of the fourth surface is reduced4Made of a material compatible with the timing sprocket 10Comparing allowable contact stress;
since the engine oil pump sprocket 11 is directly contacted and pressed with the timing sprocket 10, the pressed body on the fifth surface is the engine oil pump sprocket 11, and the contact stress sigma of the fifth surface is reduced5Comparing the allowable contact stress with the allowable contact stress of the manufacturing material of the oil pump chain wheel 11;
the end face of the crankshaft 7 is directly contacted and pressed with the oil pump chain wheel 11, so the pressed body at the sixth surface is the end face of the crankshaft 7, and the contact stress sigma of the sixth surface is6Compared with the allowable contact stress of the material of which the crankshaft 7 is made.
And when the contact stress of each joint surface is smaller than the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, judging that the type selection of the bolt 1 is qualified, and when the contact stress of each joint surface is larger than or equal to the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, returning to the step 2.1 to perform the type selection on the bolt 1 again.
In this embodiment, step 3.1 and step 3.2 may be performed simultaneously, i.e. alternately. As long as the selected bolt 1 can simultaneously meet two conditions that K' > K and the contact stress of each joint surface is smaller than the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, the type selection of the selected bolt 1 is qualified.
It should be noted that the above steps 1.1 to 1.5 are actually the process of determining the minimum assembly preload of the bolt 1 (i.e. the preload of the bolt 1 for fastening the torsional vibration damper 2), the steps 2.1 and 2.2 are the process of selecting the bolt 1 and calculating the actual maximum preload and the actual minimum preload, and the steps 3.1 and 3.2 are the process of checking the bolt 1. In addition, the bolt 1 in the steps 2.1 to 3.2 is a bolt with a selected model.
The method is simple and easy to understand when the bolt 1 for fastening the torsional vibration damper is positively selected, and the selected bolt 1 can better meet the actual use requirement by considering the axial force attenuation, the friction coefficient dispersion, the yield strength dispersion and the actual use condition in the use process of the bolt.
Specifically, when the bolt 1 is produced, the drawing definition of the bolt 1 is consistent with the key parameter definition, and the production control requirement of a supplier is restrained so as to produce the bolt meeting the drawing requirement.
Example 2:
example as an exemplary embodiment of example 1, the following:
step 1.1: according to the assembly boundary, the contact outer diameter and the contact inner diameter of each joint surface of the connecting system of the fixing bolt 1 of the known torsional vibration damper 2 are as follows: the contact outer diameter of the first surface (namely the joint surface of the head of the bolt 1 connected with the gasket) is 30mm, and the contact inner diameter is 19mm; the contact outer diameter of the second surface (namely the joint surface of the gasket and the torsional vibration damper 2) is 45mm, and the contact inner diameter is 30mm; the contact outer diameter of the third surface (namely the joint surface of the torsional vibration damper 2 and the signal panel 9) is 52mm, and the contact inner diameter is 38.8mm; the contact outer diameter of the fourth surface (namely the joint surface of the signal disc 9 and the timing chain wheel 10) is 50.54mm, and the contact inner diameter is 38.8mm; the contact outer diameter of the fifth surface (namely the joint surface of the timing chain wheel 10 and the oil pump chain wheel) is 50.54mm, and the contact inner diameter is 38mm; the sixth surface (namely the joint surface of the oil pump chain wheel 10 and the crankshaft 7) has a contact outer diameter of 50mm and a contact inner diameter of 32mm. Namely:
R01＝30mm，R1＝19mm；
R02＝45mm，R2＝30mm；
R03＝52mm，R3＝38.8mm；
R04＝50.4mm，R4＝38.8mm；
R05＝50.4mm，R5＝38mm；
R06＝50mm，R6＝32mm。
the following can be obtained by equation 1:
equivalent contact radius of the first face Re1=24.91mm; the equivalent contact radius of the second face is Re2=38.00mm, and the equivalent contact radius of the third surface is Re3=45.72mm; the equivalent contact radius of the fourth face is Re4=44.93mm; the equivalent contact radius of the fifth surface is Re5=44.57mm; the equivalent contact radius of the sixth surface is Re6＝41.66mm。
Step 1.2: presetting a predetermined pretension force F of the bolt 1x=53.21kN and coefficient of friction μ =0.15 for each joint surface, as can be calculated from equation 2:
anti-slip torque M of first face1＝99.42Nm；
Anti-slip torque M of the second face2＝151.65Nm；
Third surface anti-slip torque M3＝182.46Nm；
Anti-slip torque M of fourth surface4＝179.29Nm；
Anti-slip torque M of fifth surface5＝177.85Nm；
Sixth anti-slip torque M6＝166.25Nm。
Step 1.3: obtaining a minimum anti-slip torque M of the system according to the anti-slip torque of each joint surfacesM can be calculated by equation 3s＝251.06Nm。
Step 1.4: through the torsional vibration analysis of a crankshaft system, the maximum transmission torque of the torsional vibration damper 2 is 208.3Nm, the maximum driving torque of the timing chain wheel 10 is 34Nm, the maximum driving torque of the oil pump chain wheel 10 is 4Nm, and the maximum driving torque M of the system can be calculated through the formula 4a=246.3Nm. Because M iss＞MaThus a predetermined pretension F of the bolt 1xAnd the steel is satisfactory in 53.21 KN.
Step 1.5: calculating the pretightening force F required by the bolt 1 to fasten the torsional vibration damper 2 according to the formula 5v=106.42kN, where K =2.
Step 2.1: according to the assembly boundary limitation of the fixing bolt 1 of the torsional vibration damper 2, the specification of the bolt 1 is required to be less than or equal to M14, the bolt 1 is used for fastening and transmitting torque, and therefore a fine thread is selected, namely the thread pitch is 1.25, namely the specification of the initially selected bolt 1 is M14 multiplied by 1.25; determining the yield strength range of the bolt 1 to be 100MPa according to the consistency of raw materials and production processes provided by suppliers; selecting phosphating anti-rust oil according to the anti-corrosion requirement, and requiring the friction coefficient range to be 0.08-0.14 according to the consistency of the surface treatment process fed back by a supplierP0.2minThe screw bolt 1 is screwed in a plastic region under the pressure of 950MPa, and the yield strength utilization coefficient v is set to be 100 percentThe actual minimum pretension force F of the bolt 1 can be calculated by equation 6Mmin＝109.25kN。
Step 2.3: the actual maximum pretension force F of the bolt 1 can be calculated by the formula 7Mmax=128.95kN, wherein μsminIs 0.08RP0.2maxIs 1050MPa.
Step 3.1: the actual safety factor K '=2.05 for the bolt 1 can be calculated from equation 8, and therefore K' > K.
Step 3.2: from equation 10, one can calculate:
A1＝423.33mm2，A2＝883.57mm2，A3＝941.35mm2，A4＝823.77mm2，A5＝872.02mm2，A6＝1152.25mm2。
the following can be calculated by equation 9:
σ1＝304.61MPa，σ2＝145.94MPa，σ3＝136.98MPa，σ4＝156.54MPa，σ5＝147.87MPa，σ6＝111.24MPa。
in the embodiment, the gasket is made of 65Mn, and the allowable rigid contact stress of the material is 980MPa; the torsional vibration damper 2 adopts HT250, the allowable contact stress of the material is 750MPa, the signal disc 9, the timing chain wheel 10, the oil pump chain wheel 11 and the crankshaft 7 all adopt structural steel materials, and the allowable contact stress of the material is 559MPa. Because:
304.61MPa＜980MPa；145.94MPa＜750MPa；136.98MPa＜559MPa，156.54MPa＜559MPa，147.87MPa＜559MPa，111.24MPa＜559MPa。
therefore, when the specification M14 multiplied by 1.25, the yield strength range 950-1050MPa, the friction coefficient 0.08-0.14 and the pre-tightening force target are bolt yield points, the bolt 1 fixed by the torsional vibration damper 1 is correspondingly pre-tightened in the range 109.25-128.95kN. The actual bolt tightening safety factor 2.05 meets the requirement, the strength of each joint surface of a bolt 1 connecting system meets the requirement, and the model selection and pretightening force range of the bolt 1 are judged to determine that the design requirement is met.
Example 3:
in this embodiment, as a practical embodiment of the present invention, the method in the above embodiment is executed by using the calculation function of the EXCEL table, that is, the equations 1 to 10 are input into the EXCEL table and correlated, and when corresponding input values are input, corresponding output values are obtained, so that the accuracy and efficiency of the calculation of the above method can be improved.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and shall be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Mi＝μ×Fx×Rei (2)
Ms＝min(M1+M2，M2+M3，M3+M4，M4+M5，M5+M6) (3)
Ma＝Me1+Me2+Me3 (4)
Fv＝K×Fx (5)
Ai＝π×(R0 2-Ri 2) (10)
Claims (10)
1. A gasoline engine torsional vibration damper fixing bolt type selection and checking method is characterized by comprising the following steps:
obtaining the equivalent contact radius of each joint surface according to the contact outer diameter and the contact inner diameter of each joint surface;
obtaining the anti-sliding torque of each joint surface according to the equivalent contact radius of each joint surface and the preset pretightening force of the bolt;
obtaining the minimum anti-slip torque of the system according to the anti-slip torque of each joint surface;
obtaining the maximum driving torque of a system, comparing the minimum anti-slip torque of the system with the maximum driving torque of the system, and confirming that the preset pretightening force of the bolt is qualified when the minimum anti-slip torque of the system is larger than the maximum driving torque of the system;
obtaining the pretightening force required by the bolt to fasten the torsional vibration damper according to the preset pretightening force of the bolt and a preset safety coefficient, wherein the preset safety coefficient is determined according to the axial force attenuation of the bolt in the use process;
preliminarily selecting the type of the bolt according to the bolt assembly boundary condition and a pretightening force required by the bolt to fasten the torsional vibration damper;
obtaining the actual minimum pretightening force of the bolt according to the minimum yield strength and the maximum friction coefficient of the bolt corresponding to the selected bolt model, and obtaining the actual maximum pretightening force of the bolt according to the maximum yield strength and the minimum friction coefficient of the bolt;
obtaining an actual safety factor of the bolt according to the actual minimum pretightening force of the bolt and the preset pretightening force of the bolt, and comparing the actual safety factor with the preset safety factor;
obtaining the contact stress of each joint surface according to the actual maximum pretightening force of the bolt and the contact area of each joint surface, and comparing the contact stress of each joint surface with the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface;
and when the actual safety factor is greater than the preset safety factor and the contact stress of each joint surface is smaller than the allowable contact stress of the manufacturing material of the pressed body corresponding to each joint surface, determining that the selected bolt model is qualified.
2. The method for selecting and checking the type of the fixing bolt of the torsional vibration damper of the gasoline engine as claimed in claim 1, wherein: the method for obtaining the equivalent contact radius of each joint surface according to the contact outer diameter and the contact inner diameter of each joint surface comprises the following steps:
equivalent contact radius per joint surface
ReiIs the equivalent contact radius of the ith surface, R0iIs the contact outer diameter of the ith surface, RiFor each interface surface.
3. The method for selecting and checking the type of the fixing bolt of the torsional vibration damper of the gasoline engine as claimed in claim 2, wherein: the method for obtaining the anti-sliding torque of each joint surface according to the equivalent contact radius of each joint surface and the preset pretightening force of the bolt comprises the following steps:
the anti-slip torque M of each joint surfacei＝μ×Fx×ReiThe coefficient of friction of each bonding surface is mu, FxA predetermined pretension force for the bolt.
4. The method as claimed in claim 3, wherein the method comprises the following steps: the method for obtaining the minimum anti-slip torque of the system according to the anti-slip torque of each joint surface specifically comprises the following steps:
minimum anti-slip torque of the system:
Ms＝min(M1+M2，M2+M3，M3+M4，M4+M5，M5+M6)；
the M is1The anti-slip torque of the joint surface between the bolt head and the gasket;
said M2The anti-slip torque of the joint surface between the gasket and the torsional vibration damper;
said M3The anti-slip torque is the anti-slip torque of the junction surface between the torsional vibration damper and the signal panel;
the M is4The slip resistance torque of a joint surface between the signal panel and the timing chain wheel;
said M5The anti-slip torque of the joint surface between the timing chain wheel and the oil pump chain wheel is obtained;
said M6The anti-slip torque of the joint surface between the oil pump chain wheel and the crankshaft.
5. The method for selecting and checking the type of the fixing bolt of the torsional vibration damper of the gasoline engine as claimed in claim 4, wherein: the maximum driving torque of the system is obtained by the following steps:
maximum driving torque M of the systema＝Me1+Me2+Me3；
Said Me1A maximum torque transmitted for said torsional vibration damper;
said Me2A maximum torque transmitted for the timing sprocket;
said Me3The maximum torque is transmitted to the oil pump chain wheel.
6. The method for selecting and checking the type of the fixing bolt of the torsional vibration damper of the gasoline engine as claimed in claim 5, wherein: the pre-tightening force required to be provided by the bolt for fastening the torsional vibration damper is obtained according to the pre-tightening force and the pre-set safety coefficient of the bolt, and the method specifically comprises the following steps:
the bolt makes the torsional vibration damperThe pre-tightening force F required to be provided for fasteningv＝K×FxAnd K is the preset safety factor.
7. The method as claimed in claim 6, wherein the method comprises the following steps: the actual minimum pretightening force of the bolt is obtained according to the minimum yield strength and the maximum friction coefficient of the bolt corresponding to the selected bolt model, and the actual minimum pretightening force is specifically as follows:
actual minimum pretension of the bolt
The actual maximum pretightening force of the bolt is obtained according to the maximum yield strength and the minimum friction coefficient of the bolt, and the method specifically comprises the following steps:
actual maximum pre-tightening force of the bolt
V is a yield strength utilization coefficient of the bolt, RP0.2maxIs the maximum yield strength of the bolt, RP0.2minIs the minimum yield strength of the bolt, said AsIs the nominal stress cross-sectional area of the external thread of the bolt, d2Is the pitch diameter of the thread of the bolt, d0Is the nominal stress cross-sectional area equivalent diameter of the external thread of the bolt, the alpha' is the thread flank angle of the bolt, and the musminIs the minimum coefficient of friction of the bolt thread, musmaxAnd P is the maximum friction coefficient of the screw thread of the bolt, and the pitch of the bolt.
8. The method as claimed in claim 7, wherein the method comprises the steps of: the actual safety factor of the bolt is obtained according to the actual minimum pretightening force of the bolt and the preset pretightening force of the bolt, and the method specifically comprises the following steps:
actual safety factor of the bolt
9. The method as claimed in claim 8, wherein the method comprises the steps of: the method for obtaining the contact stress of each joint surface according to the actual maximum pretightening force of the bolt and the contact area of each joint surface comprises the following steps:
contact stress of each bonding surface
A is describedi＝π×(R0i 2-Ri 2)。
10. The method for sizing and checking the fixing bolt of the torsional vibration damper of the gasoline engine as claimed in any one of claims 1 to 9, wherein: performing the method of any one of claims 1-9 in an EXCEL form.
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