CN114109591A - Imbalance debugging method for three-cylinder engine assembly - Google Patents
Imbalance debugging method for three-cylinder engine assembly Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/06—Engines with means for equalising torque
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/16—Engines characterised by number of cylinders, e.g. single-cylinder engines
- F02B75/18—Multi-cylinder engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B77/00—Component parts, details or accessories, not otherwise provided for
- F02B77/08—Safety, indicating, or supervising devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/16—Engines characterised by number of cylinders, e.g. single-cylinder engines
- F02B75/18—Multi-cylinder engines
- F02B2075/1804—Number of cylinders
- F02B2075/1812—Number of cylinders three
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Abstract
The invention discloses an unbalance debugging method for a three-cylinder engine assembly, which comprises the steps of obtaining a first-order vibration target value in the X/Z direction of a fixed measuring point of the three-cylinder engine; acquiring an actual value of X/Z-direction first-order vibration of a fixed measuring point of the three-cylinder engine to be measured based on the vibration sensor; comparing the actual value of the Z-direction first-order vibration with the target value of the Z-direction first-order vibration, and determining whether the three-cylinder engine meets the requirement of a balance target; when the three-cylinder engine does not meet the requirement of the balance target, comparing the actual value of the first-order vibration in the X direction with the target value of the first-order vibration in the X direction, determining to reduce the weight or add the weight on the belt pulley, comparing the calculated value of the first-order vibration in the Z direction with the reference value of the first-order vibration in the Z direction, determining the position and the size of the weight on the belt pulley, and realizing the optimal balance of the whole three-cylinder engine. According to the acceleration characteristic of the engine cylinder, different balancing weights are added on the belt pulley, and the unbalance of the engine rotor system is controlled in a certain range, so that the vibration of the engine is reduced.
Description
Technical Field
The invention belongs to the technical field of three-cylinder engine damping, and particularly discloses an unbalance debugging method for a three-cylinder engine assembly.
Background
The targets of energy conservation and emission reduction are increasingly severe, and the three-cylinder engine has the advantages of small volume, low oil consumption, low emission and the like, and is popular with host factories. However, the moment imbalance of the three-cylinder engine with natural structure is always a difficult point for the development of the three-cylinder engine. How to reduce the cost of the engine and give consideration to the vibration comfort of the whole vehicle is a subject of the constant research of the three-cylinder engine, and meanwhile, because the mode distribution of the three-cylinder engine is dense, the requirement on the manufacturing precision of parts is high, and the stability of the vibration performance of the three-cylinder engine is also one of the difficult problems.
Aiming at the technical problems, the prior art generally adopts the following two technical schemes to realize the stability control of the vibration performance of the three-cylinder engine,
in the prior art, in the scheme 1, a balancing weight is added on a crank throw of a crankshaft of an engine, and a balancing shaft is added for balancing. The scheme has good balance effect and can control MXAnd MZThe torque is in a relatively small range and the balancing effect is stable in mass production, but the cost is too high.
Prior art scheme 2: in order to reduce the cost and improve the competitiveness, a balance shaft is cancelled, and meanwhile, the vibration comfort is considered. The three-cylinder engine naturally has repeated inertia moment M due to the characteristics of the structure thereofXIs not balanced. And reasonable unbalance amount and angle are set on the crankshaft, the flywheel and the belt pulley by adopting a balancing strategy of over-balancing amount. Unbalanced moment M generated by belt pulley and flywheel due to unbalanced massUnbalanced massThe moment produced by the unbalanced mass can be resolved into a moment M rotating about the X-axisXAnd rotating about the Z axisMoment M ofZ. Wherein M isXThe balance device is used for balancing the inertia moment generated by the piston and the connecting rod of the engine. MZThe new rotation moment. Make MXWhen the torque is equal to 0, the torque of the engine is changed from MXTransfer to MZ。
The disadvantages of the prior art scheme 2 are: theoretical calculation of engine MXThe moment is 0, thus the moment is MXThe Z-direction vibration generated is minimized. The engine rotor system is not a separate part. The engine rotor system consists of crank, connecting rod, crankshaft, flywheel and belt pulley. In the manufacturing process, the weight of the piston and the connecting rod has inevitable tolerance, and the weight tolerance of the piston and the connecting rod of a certain engine is shown in table 1. Rotating parts of the engine: during the production and balance of the crankshaft, the belt pulley and the flywheel, certain tolerance must exist in the unbalance amount and the angle, and the unbalance tolerance of a certain engine rotating part is shown in a table 2. Thus, the individual parts of the piston, connecting rod, crankshaft, flywheel and pulley have a certain range of unavoidable variations in their weight and unbalance during the manufacturing process. Due to the fact that the torque fluctuation of the three-cylinder engine is large, the tolerance of unbalance of the flywheel is increased due to the application of the dual-mass flywheel. This results in the unbalanced moment generated by the rotor system of the engine composed of the pistons, the connecting rods, the crankshaft, the flywheel and the belt pulley in different batches varying, i.e. the unbalanced moment M of the rotor system of the engine in different batchesXAnd MZIt is not possible to be a constant value but fluctuates within a certain range.
TABLE 1 piston rod weight tolerance
TABLE 2 tolerance of imbalance of rotating parts of an engine
Furthermore, in order to consider the economy and the vibration comfort of the three-cylinder engine without the balance shaftAnd (3) adaptability, adopting a balancing strategy of over-balancing quantity, and at two ends of the crankshaft: the flywheel and the belt pulley are provided with unbalance amount and angle, and unbalance moment generated by the unbalance mass of the flywheel and the belt pulley is utilized. One part of the unbalanced moment of the flywheel belt pulley is used for balancing the repeated inertia moment of the engine piston and the connecting rod around the X axis of the whole vehicle; one part will generate a rotational moment about the Z-axis of the complete vehicle. The engine rotor system imbalance is formed by: piston, connecting rod weight, crankshaft imbalance, pulley imbalance, and flywheel imbalance. Suppose Mz _ Engine rotorThe torque is the rotating torque of the engine rotor around the Z axis of the whole vehicle; MXEngine rotorThe rotational moment of the engine rotor around the X axis of the whole vehicle. The relationship between the unbalance amount of the flywheel belt pulley and the unbalance moment of the engine rotor system. Mz _ Engine rotorLinearly related to the unbalance of the flywheel pulley, the larger the unbalance of the flywheel pulley is, Mz _ Engine rotorThe larger. MX _ Engine rotorThere is no linear relationship with the amount of flywheel pulley unbalance, but there is an inflection point. When the unbalanced moment of the flywheel, the belt pulley, the crankshaft, the piston and the connecting rod around the X axis is just balanced, M is at the momentX _ Engine rotorHas a minimum value; when the unbalanced moment of the flywheel, the belt pulley, the crankshaft, the piston and the connecting rod deviates from the optimal position, the larger the deviation position is, the M isX _ Engine rotorThe larger. Optimizing an Engine MX _ Engine rotorAnd Mz _ Engine rotorThe unbalanced moment is in the best position, and has important significance for controlling the first-order vibration excitation of the engine.
As shown in FIG. 15 below, the goal of balancing the engine as a whole is to have MX _ Engine rotorAnd Mz _ Engine rotorAt the optimum equilibrium position.
For a three-cylinder engine without a balance shaft, vibration of the engine is reduced. The adoption of the balancing strategy of the over-balancing amount is an economical and practical scheme for designing the unbalanced belt pulley.
In the part design stage, according to the requirement of the whole vehicle, a corresponding unbalance mass block is added on the belt pulley. In the part machining stage, tolerances of the parts are inevitable. The belt pulley monomer achieves the target of unbalance and angle by detecting on a belt pulley balancing stand, adopting a mass removing method and drilling one or more holes on the belt pulley to remove a certain weight.
Because the manufacturing tolerance of the belt pulley part cannot be avoided, and the weight removed by the punching and weight removing mode and the number of the holes are in a multiple relation, the required weight cannot be accurately removed, and the error of balance is increased. Particularly, after the belt pulley is assembled on the engine, the manufacturing and installation tolerances of the flywheel, the crankshaft, the dual mass flywheel and other parts of the engine rotor system cannot be avoided, so that the weight or the unbalance amount and the angle of the engine rotor system assembly are further increased, namely the unbalance moment of the engine rotor system is inevitably fluctuated in a certain range, and a larger tolerance exists. This is one of the reasons why the three-cylinder engine has large jitter and dispersion. Therefore, a new belt pulley structure is urgently needed to be found for secondary balance after the whole engine is off line, so that the whole system can reach a better balance standard.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides a three-cylinder engine assembly unbalance debugging method, which controls the unbalance amount of an engine rotor system within a certain range by measuring the vibration acceleration of an engine cylinder body and adding different balancing weights on a belt pulley according to the acceleration characteristic, thereby reducing the vibration of an engine.
The invention discloses an unbalance debugging method for a three-cylinder engine assembly, which comprises the steps of measuring X/Z (first-order/Z) vibration values of N fixed measuring points of the three-cylinder engine, and determining X/Z (first-order/Z) vibration target values of the fixed measuring points of the three-cylinder engine based on the X/Z vibration values obtained by measurement; acquiring an actual value of X/Z-direction first-order vibration of a fixed measuring point of the three-cylinder engine to be measured based on the vibration sensor; comparing the actual value of the Z-direction first-order vibration with the target value of the Z-direction first-order vibration, and determining whether the three-cylinder engine meets the requirement of a balance target; when the three-cylinder engine does not meet the requirement of the balance target, comparing the actual value of the first-order vibration in the X direction with the target value of the first-order vibration in the X direction, determining to reduce the weight or add the weight on the belt pulley, comparing the calculated value of the first-order vibration in the Z direction with the reference value of the first-order vibration in the Z direction, determining the position and the size of the specific weight reduction or weight addition on the belt pulley, and realizing the optimal balance of the whole three-cylinder engine.
The three-cylinder engine balance target requirements are changed as follows: the first-order vibration fluctuation of the idling speed of the engine is caused due to the large imbalance tolerance of the whole engine, and when the fluctuation is small, a user can accept the fluctuation; when the fluctuation is large, the user may complain about that the user can accept the vibration value as the balance target, and when the vibration is less than or equal to the target value, the user can accept the vibration value and does not need to balance; when the vibration is larger than the target value, the user complains that the first order vibration needs to be further reduced by the second order balance.
The concept of the complete machine balance optimization of the three-cylinder engine is defined as follows: unbalanced moment M of engine rotor system around whole vehicle X axisXAt the lowest point, the Z-direction vibration generated at this time is minimal, as shown in fig. 15.
In a preferred embodiment of the invention, when the actual value of the Z-direction first-order vibration is less than or equal to the target value of the Z-direction first-order vibration, the three-cylinder engine meets the balance target requirement; and when the actual value of the Z-direction first-order vibration is larger than the target value of the Z-direction first-order vibration, the three-cylinder engine does not meet the requirement of the balance target.
In a preferred embodiment of the invention, when the actual value of the first-order vibration in the X direction is larger than the reference value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted by the counterweight; when the actual value of the first-order vibration in the X direction is smaller than the reference value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted by adding a balance weight.
In a preferred embodiment of the present invention, a method of balancing a three cylinder engine by de-weighting or adding a weight to a pulley comprises,
acquiring a Z-direction first-order vibration calculation value | -, a Z-direction first-order vibration actual value-Z-direction first-order vibration target value |;
adding or reducing counterweights with different masses at different positions on a belt pulley, and acquiring a Z-direction first-order vibration reference value | Z of the three-cylinder engine based on a counterweight calibration test1-Z2∣,Z1For the first Z-direction of three-cylinder enginesActual value of vibration, Z2The actual value of the Z-direction first-order vibration of the three-cylinder engine after the counterweight is increased and reduced;
and comparing the calculated Z-direction first-order vibration value with the Z-direction first-order vibration reference value to determine the mass and the position of the counterweight on the belt pulley.
In a preferred embodiment of the invention, one side or two sides of the belt pulley are provided with four counterweight hole sites which are equidistantly arranged along the circumferential direction of the belt pulley at intervals, and the counterweight hole sites are arranged close to the mass center of the unbalanced mass of the belt pulley.
In a preferred embodiment of the invention, the weight is a bolt or a patch; the masses of any two counterbalances are not equal.
In a preferred embodiment of the invention, after the mass and position of the weight on the pulley are determined, the weight and the pulley are connected by a threaded connection or an interference fit connection or riveted connection or welded connection or glued.
In a preferred embodiment of the invention, the method for acquiring the first-order vibration value in the X/Z direction of the fixed measuring point of the three-cylinder engine comprises the following steps,
acquiring a first-order vibration frequency-vibration acceleration relation graph of the three-cylinder engine based on a test system;
determining a first-order vibration frequency of the three-cylinder engine based on the actual idle speed of the three-cylinder engine;
inquiring a first-order vibration frequency-vibration acceleration relation diagram based on the first-order vibration frequency of the three-cylinder engine, and determining the X-direction vibration acceleration and the Z-direction vibration acceleration of the three-cylinder engine;
the vibration acceleration in the X direction is the actual value of the vibration in the first order in the X direction, and the vibration acceleration in the Z direction is the actual value of the vibration in the first order in the Z direction.
In a preferred embodiment of the present invention, the test system includes an acceleration sensor disposed on the engine block, a data acquisition instrument electrically connected to the acceleration sensor, and a control system electrically connected to the data acquisition instrument.
In a preferred embodiment of the invention, the first order vibration frequency of the three-cylinder engine is 60/60 of the actual idle speed of the three-cylinder engine.
The invention has the beneficial effects that: the method of the invention controls the unbalance amount of the engine rotor system in a certain range by measuring the vibration acceleration of the engine cylinder body and adding different balancing weights on the belt pulley according to the acceleration characteristic, thereby reducing the vibration of the engine.
Drawings
FIG. 1 is a flow chart of a method of debugging an imbalance of a three cylinder engine assembly of the present invention;
FIG. 2 is a schematic diagram of a testing system for a method for debugging the imbalance of a three-cylinder engine assembly according to the present invention;
FIG. 3 is an engine shaft view of a method of debugging imbalance in a three cylinder engine assembly of the present invention;
FIG. 4 is an elevation view of an engine rotor assembly of a method of debugging imbalance in a three cylinder engine assembly of the present invention;
FIG. 5 is a schematic illustration of a pulley for a method of debugging an imbalance in a three cylinder engine assembly according to the present invention;
FIG. 6 is a schematic diagram of a counterweight of a method for debugging the imbalance of a three-cylinder engine assembly according to the present invention;
FIG. 7 is a schematic diagram of a pulley and counterweight for a method of debugging an imbalance in a three-cylinder engine assembly according to the present invention;
FIG. 8 is a first order vibration frequency-vibration acceleration relationship diagram of a three cylinder engine assembly imbalance debugging method of the present invention;
FIG. 9 is a schematic diagram of the poor balance of a three cylinder engine assembly imbalance debugging method of the present invention;
FIG. 10 is a good balance schematic of a method of debugging an imbalance of a three cylinder engine assembly of the present invention;
FIG. 11 is a Z-direction first-order vibration reference value of a three-cylinder engine assembly imbalance debugging method of the present invention;
FIG. 12 is a reference value of the first order vibration in the X direction of a three cylinder engine assembly imbalance debugging method of the present invention;
FIG. 13 is a difference between an actual value and a target value of a three cylinder engine assembly imbalance debugging method of the present invention;
FIG. 14 is a detailed flow chart of a method of debugging an imbalance of a three cylinder engine assembly of the present invention;
FIG. 15 illustrates an optimal balancing position of a three-cylinder engine according to an imbalance adjustment method for a three-cylinder engine assembly of the present invention.
Detailed Description
The invention will now be described in further detail, including the preferred embodiments, with reference to the accompanying drawings and by way of illustration of some alternative embodiments of the invention. It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.
In the description of the present application, it should be noted that the terms "upper", "lower", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience in describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are intended to be inclusive and mean, for example, that they may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.
Further, in the present application, relational terms such as "first" and "second", and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The invention discloses an unbalance debugging method for a three-cylinder engine assembly, which comprises the steps of measuring X/Z (first-order/Z) vibration values of N fixed measuring points of the three-cylinder engine, and determining X/Z (first-order/Z) vibration target values of the fixed measuring points of the three-cylinder engine based on the X/Z vibration values obtained by measurement; acquiring an actual value of X/Z-direction first-order vibration of a fixed measuring point of the three-cylinder engine to be measured based on the vibration sensor; comparing the actual value of the Z-direction first-order vibration with the target value of the Z-direction first-order vibration to determine whether the three-cylinder engine is balanced; when the three-cylinder engine does not meet the balance target, comparing the actual value of the first-order vibration in the X direction with the target value of the first-order vibration in the X direction, determining that the balance of the three-cylinder engine is realized by reducing or adding a balance weight on a belt pulley, wherein N is more than or equal to 30 and less than or equal to 50, the determined target value of the first-order vibration in the X/Z direction is shown in figures 11 and 12, calculating the difference value between the actual value and the target value of the first-order vibration in the Z direction of the engine to judge whether the balance target is met, and judging whether the balance is over-balanced or under-balanced according to the difference value between the actual value and the target value of the first-order vibration in the X direction as shown in figure 13. When the measured value is larger than the target value, the engine system is in underbalance at the moment, and mass blocks are added to the hole 1 and the hole 2; when the measured value is < target value, the engine system is in over-balance, reducing the mass at holes 3 and 4.
In a preferred embodiment of the present invention, the method for determining the first-order vibration target value in the X/Z direction includes: step 1, performing vibration test on three-cylinder engine fixed measuring points of 30-50 vehicles to obtain a first-order vibration value of the three-cylinder engine fixed measuring points in the X/Z direction of each vehicle;
in a preferred embodiment of the present invention, the three-cylinder engine has satisfied the balance target when the actual value of the first-order vibration in the Z direction is equal to or less than the target value of the first-order vibration in the Z direction; and when the actual value of the Z-direction first-order vibration is larger than the reference value of the Z-direction first-order vibration, the three-cylinder engine does not meet the balance target.
In a preferred embodiment of the invention, when the actual value of the first-order vibration in the X direction is larger than the target value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted by reducing the weight; and when the actual value of the first-order vibration in the X direction is smaller than the target value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted by adding a counterweight.
In a preferred embodiment of the present invention, a method of balancing a three cylinder engine by de-weighting or adding a weight to a pulley comprises,
acquiring a Z-direction first-order vibration calculation value | -, a Z-direction first-order vibration actual value-Z-direction first-order vibration target value |;
adding or reducing counterweights with different masses at different positions on a belt pulley, and acquiring a Z-direction first-order vibration reference value | Z of the three-cylinder engine based on a counterweight calibration test1-Z2∣,Z1Is the actual value of Z-direction first-order vibration of the three-cylinder engine, Z2The actual value of the Z-direction first-order vibration of the three-cylinder engine after the counterweight is increased and reduced;
and comparing the calculated Z-direction first-order vibration value with the Z-direction first-order vibration reference value to determine the mass and the position of the counterweight on the belt pulley.
The method of the merchant is explained in detail below by taking the accompanying fig. 5-7 as an example:
as shown in fig. 5, the hole 1 is a hole 2 for adding a counterweight, and is initially a hollow hole; hole 3, hole 4 are for subtracting heavy hole site, have reserved the balancing weight during the beginning, the quality piece of 4 kinds of different weights of design by way of example: the masses of the two parts are 1g, 2g, 3g and 4g respectively, and in the diagram (the number and the weight of the balancing weights can be adjusted according to the unbalanced tolerance of an engine rotor system), 5 is an insert and 6 is a belt pulley.
1, counterweight calibration test:
1.1 add weight protocol on holes 1 and 2:
firstly, measuring a Z-direction first-order vibration value of an engine in an original state, namely a Z-direction first-order vibration actual value Z of a three-cylinder engine1(m/s2) (ii) a Then, at the same measurement point of the engine, the engine was weighted as shown in Table 2, and the Z-direction first-order vibration Z of the engine was measured after each weighting2(m/s2) (vibration after counter-weighting); will Z2-Z1It is possible to obtain the vibrations of the holes 1 and 2 at the engine station, under different weighting schemes.
Table 3: well 1 and well 2 weighting scheme
1.2 weight reduction scheme, performed on holes 3 and 4: (initially installing 4g mass in holes 3 and 4)
Firstly, measuring a Z-direction first-order vibration value of an engine in an original state, namely a Z-direction first-order vibration actual value Z of a three-cylinder engine1(m/s2) (ii) a Then, at the same measurement point of the engine, weight reduction was performed as shown in Table 2, and the Z-direction first-order vibration Z of the engine was measured after each weight reduction2(m/s2) (vibration after counter-weighting); will Z2-Z1The vibration generated by the hole 1 and the hole 2 on the engine measuring point under different weight reduction schemes can be obtained.
Table 4: weight reduction scheme for holes 3 and 4
In tables○Representing the vacancy and quality of the selected species.
In a preferred embodiment of the invention, the engine assembly is balanced secondarily on the pulley, with minimal weight required for the counterbalance. FIG. 3 is a front view of the rotor of the engine, in which FIG. 1 is a dual mass flywheel; 2 is a damping belt pulley; 2.1 is the mass center of the unbalanced mass of the belt pulley; 2.2 is the balance position of the belt pulley which forms 180 degrees with the 2.1; 3 is a curve rotation central line; 4 is a center line passing through a third cylinder of the engine and perpendicular to 3; 5 is the intersection of 3 and 4; r1 is the vertical distance of the belt pulley unbalance mass center position from 2.1 to 3; r2 is the vertical distance of the belt pulley unbalance mass center position 2.2 to 3; l1mm is the vertical distance from the center of mass of the damper pulley unbalance to 4. Adding the mass (m) twice at the 2.2 or 2.1 position on the engine pulley will create a new moment: m × R1 × ω2X L1 or M × R2 × ω2 XL 1; as can be seen from fig. 4, L1, R1, R2 all have taken the maximum value under the premise of producing the same M, so the required M mass is minimal; one side or both sides of belt pulley are provided with four along its circumference equidistance interval arrangement's counter weight hole sites, and the counter weight hole site sets up the barycenter that is close to the unbalanced mass of belt pulley.
In a preferred embodiment of the invention, the belt pulley is provided with 4 mounting holes and 4 mass blocks with different masses on the unbalanced mass, wherein the holes 1 and 2 are added counterweight hole sites and are initially empty holes; hole 3, hole 4 are for subtracting heavy hole site, have reserved the balancing weight during the beginning. The quantity and the weight of balancing weights can be adjusted according to the requirement of the whole vehicle. The 4 mounting holes and 4 different mass masses shown in the table below can be combined into 16 different compositions. The 16 different compositions can reduce the unbalance tolerance of the original engine assembly to 1/16 at most. The addition and reduction of weight on the same side near the pulleys allows for a minimum overall system mass.
In a preferred embodiment of the invention, in the counterweight calibration test, 8 combinations of different mass blocks and the like are installed in the hole 1 and the hole 2, 8 combinations of different mass blocks and the like are reduced in the hole 3 and the hole 4, and a Z-direction first-order vibration database of the engine with different mass blocks is established.
In a preferred embodiment of the invention, the weight is a bolt or a patch; the masses of any two counterbalances are not equal.
In a preferred embodiment of the invention, after the mass and position of the weight on the pulley are determined, the weight and the pulley are connected by a threaded connection or an interference fit connection or riveted connection or welded connection or glued.
In a preferred embodiment of the invention, the method for acquiring the first-order vibration value in the X/Z direction of the fixed measuring point of the three-cylinder engine comprises the following steps,
acquiring a first-order vibration frequency-vibration acceleration relation graph of the three-cylinder engine based on a test system;
determining a first-order vibration frequency of the three-cylinder engine based on the actual idle speed of the three-cylinder engine;
inquiring a first-order vibration frequency-vibration acceleration relation diagram based on the first-order vibration frequency of the three-cylinder engine, and determining the X-direction vibration acceleration and the Z-direction vibration acceleration of the three-cylinder engine;
the vibration acceleration in the X direction is the actual value of the vibration in the first order in the X direction, and the vibration acceleration in the Z direction is the actual value of the vibration in the first order in the Z direction.
In a preferred embodiment of the present invention, the test system includes an acceleration sensor disposed on the engine block, a data acquisition instrument electrically connected to the acceleration sensor, and a control system electrically connected to the data acquisition instrument.
In a preferred embodiment of the invention, the first order vibration frequency of the three-cylinder engine is 60/60 of the actual idle speed of the three-cylinder engine.
The invention has convenient and quick measurement, does not need additional tools, directly fixes the acceleration sensor on the engine cylinder body, and can be used when an engine assembly is off line or the whole vehicle is off lineAnd adding a set of balancing procedures to realize the method. FIG. 2 is a schematic diagram of a test system, wherein 7 is an acceleration sensor, 8 is a connecting line of the acceleration sensor and a data acquisition instrument, 9 is the data acquisition instrument, 10 is a network cable, and 11 is a computer. The method comprises the steps that 7 an acceleration sensor is fixed on an engine mount 6 or 7, the engine runs under an idling working condition, 9 a data acquisition instrument acquires vibration signals on the engine mount and transmits the vibration signals to 11 computers, and FFT analysis is conducted on the vibration signals through test software, so that frequency spectrums in the X direction and the Z direction of the engine mount can be obtained. Characterization of the engine M by measuring the vibration acceleration in the X and Z directions on the engine mountXAnd MZThe unbalanced moment of (a). The test result is more consistent with the measurement principle of the whole vehicle test target (the whole vehicle target specifies the vibration acceleration rather than the engine torque) and is the engine shaft view shown in the attached figure 3, when the engine is subjected to MXWhen the torque is excited, Z-direction vibration is generated on the engine cylinder body; when the engine is subjected to moment MZWhen excited, the engine cylinder body generates X-direction vibration; z-direction vibration and M of engineXPositive correlation, engine X-direction vibration and MZAnd (4) positively correlating. Suppose that the idle speed of the engine is 960tr/min, and the first-order engine vibration frequency is 16Hz, namely, the engine speed/60 is 960/60. From the basic principle of vibration noise, it is known that the magnitude of first order engine vibrations is determined primarily by engine imbalance. Thus, the engine M can be realizedZAnd MXThe moment of (2) is converted into vibration of the engine mount in the X direction and the Z direction under the condition of 16Hz, and the data processing result is shown in a figure 7, namely a first-order vibration frequency-vibration acceleration relation graph.
The invention carries out secondary balance on the engine assembly on the belt pulley, compensates the overall balance of the rotor system of the engine, is slightly influenced by the tolerance of the unbalance of a single part, and has higher precision and more stability of the balance result.
The engine rotor system balance is shown in table 5. When fully balanced, at this time MXThe generated Z-direction vibration is minimum, and M is introducedZ(reference); when underbalanced, the piston rod still has a small amount of MXIs not balanced, can cause Z-direction vibration, and introduces MZSmall (relative to reference); when the balance is over-balanced, the moment generated by the unbalanced mass of the crankshaft and the flywheel belt pulley not only balances the inertia moment of the piston connecting rod, but also has redundant MXExcess of MXWill generate Z-direction vibration, induced MZLarger (relative to reference). The occurrence of the 3 conditions is random, and the optimal solution cannot be guaranteed only by controlling the unbalanced rack of the single part according to the matching condition of the unbalanced belt pulley, the unbalanced flywheel and the unbalanced engine.
TABLE 5 Engine rotor System balance conditions
The core of the engine assembly balance is that M is realized by increasing or decreasing the moment of the belt pulleyXAnd MZThe optimal point is reached; when the engine system is under balanced, the engine system is in the best balance by adding the corresponding balance mass on the belt pulley; when the engine system is overbalanced, the engine system is optimally balanced by reducing the corresponding balancing mass on the pulley. The unbalance of all the engine rotor systems is in an optimal state by adding the unbalance mass at different positions of the belt pulley.
Second compensation legend:
the poor balance is shown in figure 8. The Z-direction vibration is large, the X-direction vibration is small, and the engine M is shownXThe moment is not transferred to MZ；
The good balance is shown in figure 9. The larger the X-direction vibration and the smaller the Z-direction vibration, which indicates that the engine M isXThe moment has been transferred to MZ。
Description of the effects of the invention;
assuming an engine assembly imbalance tolerance of + -800g.mm and a pulley counterweight radius of 100mm, an additional or a lesser mass of 800/100 g-8 g would be required on the pulley to optimize the engine rotor. As can be seen from the balance weight calibration test table 1 and tables, the tolerance after the assembly is balanced is 1g × 100mm — 100g.mm, and the unbalance tolerance of the system is reduced from 1600g.mm to 100g.mm after the engine assembly is balanced; the new tolerance is only 6.26% of the original tolerance. In actual balance, the weight and the number of the balance weights can be determined according to the maximum unbalance of an engine rotor system, and in addition, the radius of the belt pulley balancing weight can be reduced according to the actual balance requirement, so that the balance precision is further improved.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and any modification, combination, replacement, or improvement made within the spirit and principle of the present invention is included in the scope of the present invention.
Claims (10)
1. A three-cylinder engine assembly unbalance debugging method is characterized in that: the method comprises the steps of obtaining a first-order vibration target value in the X/Z direction of a fixed measuring point of the three-cylinder engine; acquiring an actual value of X/Z-direction first-order vibration of a fixed measuring point of the three-cylinder engine to be measured based on the vibration sensor; comparing the actual value of the Z-direction first-order vibration with the target value of the Z-direction first-order vibration, and determining whether the three-cylinder engine meets the requirement of a balance target; when the three-cylinder engine does not meet the requirement of the balance target, comparing the actual value of the first-order vibration in the X direction with the target value of the first-order vibration in the X direction, determining to reduce the weight or add the weight on the belt pulley, comparing the calculated value of the first-order vibration in the Z direction with the reference value of the first-order vibration in the Z direction, determining the position and the size of the weight on the belt pulley, and realizing the optimal balance of the whole three-cylinder engine.
2. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 1, wherein: when the actual value of the Z-direction first-order vibration is smaller than or equal to the target value of the Z-direction first-order vibration, the three-cylinder engine meets the requirement of a balance target; and when the actual value of the Z-direction first-order vibration is larger than the target value of the Z-direction first-order vibration, the three-cylinder engine does not meet the balance requirement.
3. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 1, wherein: when the actual value of the first-order vibration in the X direction is larger than the target value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted through the counterweight; and when the actual value of the first-order vibration in the X direction is smaller than the target value of the first-order vibration in the X direction, the balance of the three-cylinder engine is adjusted by adding a counterweight.
4. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 1, wherein: the method for balancing the three-cylinder engine by reducing weight or adding weight on the belt pulley comprises the following steps,
acquiring a Z-direction first-order vibration calculation value | -, a Z-direction first-order vibration actual value-Z-direction first-order vibration target value |;
adding or reducing counterweights with different masses at different positions on a belt pulley, and acquiring a Z-direction first-order vibration reference value | Z of the three-cylinder engine based on a counterweight calibration test1-Z2∣,Z1Is the actual value of Z-direction first-order vibration of the three-cylinder engine, Z2The actual value of the Z-direction first-order vibration of the three-cylinder engine after the counterweight is increased and reduced;
and comparing the calculated Z-direction first-order vibration value with the Z-direction first-order vibration reference value to determine the mass and the position of the counterweight on the belt pulley.
5. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 4, wherein: one side or both sides of belt pulley are provided with four along its circumference equidistance interval arrangement's counter weight hole sites, and the counter weight hole site sets up in the barycenter department of being close to the unbalanced mass of belt pulley.
6. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 4, wherein: the balance weight is a bolt or a patch; the masses of any two counterbalances are not equal.
7. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 4, wherein: after the mass and the position of the balance weight on the belt pulley are determined, the balance weight and the belt pulley are connected through threads or interference fit, or riveted, welded or glued.
8. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 1, wherein: the method for acquiring the first-order vibration value in the X/Z direction of the fixed measuring point of the three-cylinder engine comprises the following steps,
acquiring a first-order vibration frequency-vibration acceleration relation graph of the three-cylinder engine based on a test system;
determining a first-order vibration frequency of the three-cylinder engine based on the actual idle speed of the three-cylinder engine;
inquiring a first-order vibration frequency-vibration acceleration relation diagram based on the first-order vibration frequency of the three-cylinder engine, and determining the X-direction vibration acceleration and the Z-direction vibration acceleration of the three-cylinder engine;
the vibration acceleration in the X direction is the actual value of the vibration in the first order in the X direction, and the vibration acceleration in the Z direction is the actual value of the vibration in the first order in the Z direction.
9. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 8, wherein: the test system comprises an acceleration sensor (7) arranged on the engine cylinder body, a data acquisition instrument (9) electrically connected with the acceleration sensor (7) and a control system (11) electrically connected with the data acquisition instrument (9).
10. The method of debugging an imbalance in a three-cylinder engine assembly according to claim 8, wherein: the first order vibration frequency of the three-cylinder engine is equal to the actual idle speed/60 of the three-cylinder engine.
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