JP4083654B2 - Engine assembly leak test pass / fail judgment method - Google Patents

Description

  The present invention relates to a pass / fail judgment method when performing a leak test on an engine assembly, in particular, an engine assembly having a throttle body as an assembly component.

  An automobile engine is composed of a cylinder block, a piston, a crankshaft, and the like, and usually, various sealing members suitable for the shape of the joint portion are loaded in the joint portion of these components in order to prevent oil leakage. However, automobile engines are precision parts, and gaps and through holes may be formed between the outside due to structural errors such as dimensional errors, assembly errors, shrinkage cavities, and pinholes of various components. Such gaps and through holes due to structural defects cause oil leakage during operation of the actual machine by filling the engine body with oil, and therefore it is important to carefully examine before shipment.

For inspection of gaps and through holes in this type of engine, air at a constant pressure of, for example, about 0.2 kgf / cm ² is injected into the engine body from a part of the cylinder head cover, and air leakage is detected by a leak tester. Is used.

  For example, in the one shown in Patent Document 1, when air is supplied by connecting a hose of a leak test device to a breather tube connection port of a cylinder head cover, air is also supplied from both end surfaces of the intake manifold and the exhaust manifold. In this state, the air flow rate from the breather tube connection port that changes in response to air leakage is detected by a leak tester.

  By the way, the fact that the internal clearance and through hole inspection are important is the same in an engine assembly configured with an accessory such as a throttle body attached to an automobile engine. In particular, the throttle body is a component that controls the amount of intake into the engine body, and also from the viewpoint of the process that it is often installed at a relatively later stage in the engine assembly line. It is advantageous in terms of work efficiency to perform the leak test as described above on the engine assembly configuration equipped with this.

As a leak test method performed on this type of engine assembly, for example, there is one disclosed in Patent Document 2. In consideration of the fact that components such as the throttle body have an unsealed structure that does not assume filling oil, air leakage to the air passage is inevitable when supplying air for the leak test. The amount of air blown from the throttle shaft of the throttle valve and the gap between the shaft holes is measured, and then this is excluded to determine the net air leakage amount.
Japanese Patent Laid-Open No. 61-196132 (FIG. 1) Japanese Patent Laid-Open No. 7-49286 (FIG. 2)

  As described above, in order to examine the presence or absence of gaps and through holes in the engine assembly, the positioning of the scrutiny performed by the leak test is important. However, in parts that do not assume oil filling, such as a throttle body, fluctuations in the amount of air blown through the air flow path due to noise factors or the like causes a decrease in the accuracy of the determined value of the air leakage amount. This is a cause that impairs the reliability of the leak test, and thus is not particularly desirable, and it is necessary to reliably prevent such fluctuations.

  In view of the above problems, an object of the present invention is to provide a leak test pass / fail judgment method capable of obtaining an accurate judgment result for a test object configured as an engine assembly.

  In order to solve the above-described problems, the present invention provides a supply air from a cylinder head cover as a pass / fail judgment method when supplying air from a part of a cylinder head cover into an engine body before oil filling and performing a leak test of the engine assembly. Is discharged from each opening of the intake manifold and the exhaust manifold communicating with the engine assembly, and the difference between both the flow rate of the supplied air and the total flow rate of the discharged air from each opening is used as a pass / fail judgment criterion.

  According to this, when a tube with a flow meter is connected to the breather tube connection port and air is supplied at a constant pressure from here, for example, when the measured value of the air flow rate measured by the flow meter is Fa, A tube with a flow meter is connected to each opening of the intake manifold and the exhaust manifold, and the air flow rate measured by each flow meter when the air circulating in the engine assembly is discharged from these is defined as Fb and Fc, respectively.

At this time,
Fa = Fb + Fc (1)
If is established, it can be determined that there is no flow rate difference between the left side and the right side in the above formula, and that there is no air leakage in the engine assembly. Naturally, it can be recognized that the product is free of oil leak even when filled with oil, and this is the principle in the present invention.

  By the way, in the above-described conventional method of sealing the inside of the engine assembly, the flow speed of circulating air is suppressed, whereas in this method of opening to the atmosphere, the apparatus configuration is simplified and the air flow speed is secured to some extent. There is an advantage that you can.

  That is, when the configuration of the engine assembly is based on, for example, a throttle valve, the air pressure with respect to the rotation support shaft of the throttle valve and the gap between the shaft holes is greatly reduced. As a result, when the air pressure drops below the surface tension of the grease (grease) attached to the valve spindle at the time of delivery, the air blow-off amount, which has been considered a variable factor, is reduced, and the variation is further suppressed. be able to.

  If there is an air blow-through amount, the above formula (1) is not satisfied. This is because the blow-through amount corresponds to a flow rate difference between the left side Fa and the right side (Fb + Fc). For this reason, the reduction and the suppression of variation contribute to stabilizing the flow rate difference between the two, which is a desirable condition for the present invention using this flow rate difference as a pass / fail judgment criterion. That is, by using such an assembly specification, the accuracy of the leak test can be improved.

  In this case, the pass / fail judgment criterion based on the difference between the two flow rates is that the flow rate difference between the supply air flow rate Fa and the exhaust air total flow rate (Fb + Fc) reaches the equilibrium state in advance when the same type engine assembly as the test product is used. The flow rate difference is changed stepwise within the range including the flow rate difference in the equilibrium state, and the maximum flow rate in the equilibrium state that does not cause oil leakage during actual oil filling. The difference is specified, and the monitoring time is set until a predetermined time elapses from the point in time when the flow rate difference during the time change starts the equilibrium state. Then, whether or not the flow rate difference between the supply air flow rate Fa and the exhaust air total flow rate (Fb + Fc) in the test product is maintained below the specified maximum flow rate difference during the monitoring time is used as a pass / fail criterion. .

  According to this, the maximum flow rate difference in an equilibrium state that does not cause oil leakage during actual oil filling also incorporates the deterrent effect due to the attached oil and fat at the time of delivery, so the upper limit value of the acceptable range for pass / fail judgment Therefore, an accurate pass / fail judgment can be made by the maximum flow rate difference corresponding to.

  Moreover, the actual flow rate measurement can be performed only within the monitoring time when the flow rate difference between the supply air flow rate Fa and the exhaust air total flow rate (Fb + Fc) reaches an equilibrium state and is stable to each other. Can be performed with good working efficiency.

  In order to change the flow rate difference in a known acceptable product in a stepwise manner, it is preferable to use a method such as loosening a mounting bolt for joining component parts.

  Since the leak test pass / fail determination method of the present invention is an open-to-air method, not only the apparatus configuration is simplified but also an air flow rate can be secured to some extent. In addition, the air pressure with respect to the rotation support shaft of the throttle valve, which is an example of the assembly, and the gap between the shaft holes is greatly reduced. In particular, the degree of the decrease is the surface tension of the oil and fat adhered to the valve support shaft during delivery. Since it is the following level, it is possible to reliably prevent the fluctuation factor of the air leakage amount without causing air blow-through. Therefore, the accuracy of the leak test is improved.

  Moreover, since the flow rate measurement during the actual leak test should be performed only within a stable monitoring time when the flow rate difference between the supply air flow rate and the exhaust air total flow rate reaches an equilibrium state, the work efficiency of the leak test Is good.

  FIG. 1 is a schematic cross-sectional view of an engine assembly 1 that performs a pass / fail determination of a leak test according to the present invention. The engine assembly 1 includes an engine body 2 and a throttle body 3. More specifically, the engine body 2 is provided with an intake manifold 4 and an exhaust manifold 5 on the left and right side surfaces, and a surge tank 6 is interposed between the extending intake manifold 4 and the throttle body 3. .

  On the other hand, the outer shape of the engine body 2 is formed by a cylinder head cover 7, a cylinder head 8, a cylinder block 9, an oil pan 10, and the like, and various components such as a piston 11 and a crankshaft 12 are attached therein. . In other words, the piston 11 is attached to the crankshaft 12 rotatably supported in the skirt portion 13 of the cylinder block 9 via the connecting rod 14. The piston 11 is slidably provided in the cylinder bore 15 of the cylinder block 9. The cylinder head 8 is provided with a combustion chamber 16, an intake port 17 and an exhaust port 18 communicating with the combustion chamber 16, and an intake port 17 and an exhaust valve 20 driven by a camshaft (not shown) respectively. Each exhaust port 18 opens and closes. Further, the intake port 17 is connected to the intake manifold 4, and the exhaust port 18 is connected to the exhaust manifold 5.

  For the leak test, a rubber tube (not shown) with a flow meter 22 is connected to the breather tube connection port 21 in the cap portion of the cylinder head cover 7 to establish an air supply path 23. The air supply path 23 is actually configured such that the air flow rate from the air source 24 is adjusted by the regulator 25 and supplied to the breather tube connection port 21, and the supply air flow rate Fa can be monitored by the flow meter 22. Similarly, for the leak test, rubber tubes (not shown) are connected to the opening 5a of the exhaust manifold 5 and the opening 3a of the throttle body 3 to establish air discharge paths 26a and 26b. Both air discharge paths 26a and 26b merge as the air discharge path 26 in the extending direction, and the total amount of exhaust air flows Fb and Fc flowing through the air discharge paths 26a and 26b by the flow meter 27 attached to the discharge path 26. (Fb + Fc) can be monitored.

When the leak test is performed on the engine assembly 1 shown in FIG. 1 in which the throttle body 3 is configured as an assembly, the air flow rate from the air source 24 is adjusted with the regulator 25 in a state where all of the intake valve 19, the exhaust valve 20, the throttle valve 28 and the like are opened. For example, compressed air of about 0.2 kgf / cm ² is injected into the engine body 2 from the air supply path 23 via the breather tube connection port 21. The injected compressed air flows into the cylinder head cover 7, passes through the oil return hole 29, flows into the skirt portion 13 of the cylinder block 9 and the oil pan 10, and reaches the lower portion of the piston 11 in the cylinder bore 15. Fulfill. On the other hand, the compressed air flowing in the direction of the intake manifold 4 and the exhaust manifold 5 and flowing in the direction of the intake manifold 4 reaches the throttle body 3 via the surge tank 6. And it exhausts from the opening part 5a of the exhaust manifold 5, and the opening part 3a of the throttle body 3, and is discharged | emitted from the confluence | merging discharge path 26 via the air discharge paths 26a and 26b.

In such a state, when the engine assembly 1 is an ideal pass product without gaps or through holes, the supply air flow rate Fa and the exhaust air flow rates Fb and Fc are:
Fa = Fb + Fc (1)
It becomes. At this time, when the change with time of the air flow rate measured by the flow meter 22 and the flow meter 27 is measured, as shown in FIG. 2A, the supply air flow rate and the exhaust air total flow rate gradually become different from the initial state of measurement. It is clear that it will approach and eventually transition in a matched equilibrium.

  However, on the other hand, a practically acceptable product does not have to be the ultimate acceptable product. In particular, an assembly such as the throttle body 5 has a structure of non-sealing parts that does not originally assume filled oil, so air blowing from the rotation support shaft 29 of the throttle valve 28 and the gap between the shaft holes is inevitable. If this air blow-off exists, even if the engine assembly 1 of the device under test is an acceptable product, the supply air flow rate and the exhaust air total flow rate do not match, and a certain amount of divergence k is maintained and an equilibrium state is maintained. To. An example of such a state is shown in FIG. Therefore, it is important to specify a deviation amount that is within an allowable range as an acceptable product. For this purpose, it is desirable that the air blow-through as a factor of the deviation amount does not vary greatly.

  By the way, the assembly such as the throttle body 5 in particular has a structure in which the air supply path 23, the air discharge paths 26a and 26b, and the merging discharge path 26 are made of rubber tubes and the like, so that the air remains open to a certain level. With the above air flow rate. For this reason, the compressed air that flows in greatly reduces the air pressure against the rotation support shaft of the throttle valve and the clearance between the shaft holes, for example, to a level below the surface tension of the grease attached to the valve support shaft during delivery. When the air pressure decreases, the occurrence of air blow-through amount, which has been conventionally considered as a fluctuation factor, is suppressed and becomes stable. The stabilization of the air blow-through amount is considered to be a factor for improving the accuracy of the above-described allowable range deviation amount.

  Therefore, in the present invention, the time-dependent change until the flow rate difference between the supply air flow rate Fa and the exhaust air total flow rate (Fb + Fc) reaches the equilibrium state when using the same engine assembly 1 as the test product is measured in advance. By doing so, the amount of deviation between the two flow rates in the equilibrium state, that is, the flow rate difference is obtained. Then, the detachment flow difference in the equilibrium state is changed stepwise by, for example, gradually loosening the fixing state of the mounting bolts for joining the component parts of the accepted engine assembly 1 to obtain various flow differences. Among these flow differences, the maximum flow difference in the equilibrium state that does not cause oil leakage when the oil is actually filled is specified, and a predetermined time elapses from the time when the flow difference during the change of time starts the equilibrium state. Is set as the monitoring time. For example, in the case of FIG. 2A and FIG. 2B, this equilibrium state start time can be set to about 90 seconds from the start of measurement. In the leak test with the actual test product, the flow rate difference between the supply air flow rate Fa and the exhaust air total flow rate (Fb + Fc) is over the monitoring time starting from about 90 seconds when the measurement is started, which is the equilibrium state start time. Those that change while maintaining the maximum flow rate difference below are judged as acceptable products, and the others are judged as defective products.

Note that applying the maximum flow rate difference in an equilibrium state that does not cause oil leakage during actual oil filling as the above-described deviation flow rate difference of the allowable range uses a limit point of the allowable range, and is practical. Risk is high. For this reason, as the deviation flow rate difference in the allowable range, the maximum flow rate difference kMAX is multiplied by the safety factor S.
ks = kMAX / S
Should be used as the actual tolerance.

  In the present embodiment, two flow meters, the flow meter 22 and the flow meter 27, are installed and the exhaust air total flow rate (Fb + Fc) is directly measured by the flow meter 27. However, the air discharge paths 26a, 26b Of course, it is also possible to install a flow meter separately for each and measure the exhaust air flow rates Fb and Fc individually.

  Further, the numerical values such as the flow rate described in the present embodiment do not limit the present invention, and the present invention is applicable as long as the inflowing compressed air is within a numerical range in which it flows through the engine assembly with a predetermined flow velocity. Needless to say, this is applicable.

  In the apparatus configuration of FIG. 1, a digital flow switch PF2A manufactured by SMC Corporation was used as the flow meter 22 and the flow meter 27. Then, by gradually relaxing the fixing state of the mounting bolts for joining the component parts in the accepted engine assembly 1, the difference flow rate difference in the above-mentioned equilibrium state is reduced to 0 to 0.8 (L / min). Changed. At this time, when the above-described leak test was performed on 50 acceptable engine assemblies 1, the distribution of the number of acceptable products varies around 0.5 (L / min) as shown in FIG. became.

  For this reason, in consideration of the safety factor, when the allowable deviation flow rate difference ks in this case is set to 0.5 (L / min), the leak test pass / fail judgment using this value is accurately performed. Was confirmed.

  The present invention can simplify the configuration of the apparatus by connecting the tube in an open state to the atmosphere, so that it can be used for leak tests on various test objects other than the engine assembly with a throttle body attached.

Schematic cross section of engine assembly Graph showing the change with time of supply air flow rate and exhaust air flow rate A graph showing the distribution of the deviation flow rate difference and the number of acceptable products

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine assembly 2 Engine main body 3 Throttle body 3a Opening 4 Intake manifold 5 Exhaust manifold 5a Opening 7 Cylinder head cover 21 Breather tube connection port 22 27 Flowmeter Fa Supply air flow rate Fb Exhaust air flow rate Fc Exhaust air flow rate

Claims (2)

An engine assembly leak test pass / fail judgment method for judging pass / fail of an engine assembly leak test performed by supplying air from a part of a cylinder head cover into an engine body before oil filling ,
The supply air from the cylinder head cover is discharged from each opening of the intake manifold and the exhaust manifold communicating with the engine assembly, and the flow rate difference between the flow rate of the supply air and the total flow rate of the discharge air from each opening is determined. In the method of acceptance criteria ,
Measure the change over time until the flow rate difference between the supply air flow rate and the total flow rate reaches an equilibrium state when using a passing engine assembly of the same type as the test product, and include the flow rate difference at the equilibrium state Within the flow rate difference range, the maximum flow rate difference in the equilibrium state that does not cause oil leakage during actual oil filling is specified, and monitoring is performed until the predetermined time elapses from the time when the flow rate difference during the time change starts the equilibrium state. It is set as time, and whether or not the flow rate difference between the supply air flow rate and the total flow rate in the test product is maintained below the maximum flow rate difference during the monitoring time is used as the pass / fail criterion. An engine assembly leak test pass / fail judgment method. In leak testing adequacy determining method for an engine assembly according to claim 1, wherein the engine assembly includes a throttle body attached to the intake manifold side of the engine assembly, the throttle body and said unsealed parts der Rukoto To pass or fail the engine assembly leak test.

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