JP2017161310A - Tumble flow measuring device and tumble flow measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly measure a flow speed distribution of a tumble flow.SOLUTION: A tumble flow measuring device 100 is equipped with a first probe 110 which measures gas flow speed at a first measuring position a set in a predetermined range including a center of a tumble flow, on a virtual surface vertical to a flowing direction of the tumble flow, of a combustion chamber 7 surrounded by a cylinder bore, a cylinder head 4, and a piston 6; a second probe 112 which measures gas flow speed at a second measuring position b positioned in a longitudinal direction of the tumble flow on the virtual surface to the first measuring position a, of the combustion chamber 7; and a third probe 114 which measures gas flow speed at a third measuring position c positioned on the opposite side to the second measuring position b across the first measuring position a in the longitudinal direction, of the combustion chamber 7.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a tumble flow measuring device and a tumble flow measuring method for measuring a flow velocity distribution of an engine tumble flow.

  In an engine, an engine that injects fuel so that the intake air flowing into the combustion chamber from the intake port provided in the cylinder head forms a tumble flow (longitudinal vortex flow) and does not inhibit the tumble flow is widely used. This tumble flow is collapsed and converted into turbulence just before the ignition of the compression stroke, thereby becoming a turbulent flow and increasing the combustion speed and improving the fuel dilution / dilution limit.

  Such a tumble flow differs in the amount of turbulence generated and the effect on the arc during ignition depending on the nature of the swivel axis. Therefore, in order to improve the quality of the tumble flow, the flow velocity distribution of the intake air flowing into the combustion chamber is made uniform in the alignment direction of the intake ports by making the center side of the intake port alignment direction lower than the both ends. A technique for achieving the above has been proposed (for example, Patent Document 1).

JP 2003-106151 A

  Since improving the quality of the tumble flow contributes to improving fuel efficiency, development of a technique for appropriately measuring the flow velocity distribution of the tumble flow is desired.

  Then, in view of such a subject, this invention aims at providing the tumble flow measuring apparatus and tumble flow measuring method which can measure the flow velocity distribution of tumble flow appropriately.

  In order to solve the above-described problems, a tumble flow measuring device according to the present invention includes a cylinder bore, a cylinder head, and a combustion chamber surrounded by a piston on a virtual plane perpendicular to the flow direction of the tumble flow. A first probe for measuring a gas flow velocity at a first measurement position set in a predetermined range including the center of the first position, and a first position of the combustion chamber located in the longitudinal direction of the tumble flow with respect to the first measurement position. The second probe for measuring the gas flow rate at the two measurement positions, and the gas flow rate at the third measurement position located on the opposite side of the second measurement position across the first measurement position in the longitudinal direction of the combustion chamber. And a third probe.

  The first measurement position, the second measurement position, and the third measurement position may be closer to the cylinder head than the position of the piston at the fuel ignition timing.

  The first measurement position, the second measurement position, and the third measurement position may be closer to the cylinder head than the top dead center of the piston.

  The first probe, the second probe, and the third probe may be accommodated in an accommodation hole provided in the cylinder head.

  Furthermore, an evaluation index calculation unit that calculates a value that is an evaluation index of the tumble flow based on the measurement results of the first probe, the second probe, and the third probe may be provided.

  In order to solve the above problems, a tumble flow measuring method according to the present invention includes a cylinder bore, a cylinder head, and a combustion chamber surrounded by a piston on a virtual plane perpendicular to the flow direction of the tumble flow. Among the first measurement position and the combustion chamber set in a predetermined range including the center of the second measurement position and the combustion chamber located in the longitudinal direction of the tumble flow in the virtual plane with respect to the first measurement position In the longitudinal direction, the gas flow rate is measured at a third measurement position located on the opposite side of the second measurement position across the first measurement position.

  According to the present invention, it is possible to appropriately measure the flow velocity distribution of the tumble flow.

It is a figure explaining the composition of an engine. It is explanatory drawing for demonstrating a tumble flow. It is the 1st figure for explaining a tumble flow measuring device. It is a 2nd figure for demonstrating a tumble flow measuring apparatus. It is a figure which shows an example of evaluation of a tumble flow. It is a figure for demonstrating the tumble flow measuring apparatus of a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram illustrating the configuration of the engine. As shown in FIG. 1, the engine 1 is provided with a cylinder block 2, a crankcase 3 integrally formed with the cylinder block 2, and a cylinder head 4 fixed to the upper part of the cylinder block 2.

  A cylinder bore 5 is formed in the cylinder block 2, and a piston 6 is slidably supported on the connecting rod 10 in the cylinder bore 5. In the engine 1, a space surrounded by the cylinder head 4, the cylinder bore 5, and the upper surface of the piston 6 is formed as a combustion chamber 7.

  In the engine 1, a crankshaft 9 is rotatably supported in a crank chamber 8 formed in the crankcase 3. The connecting rod 10 is rotatably supported by the crankshaft 9, and the piston 6 is connected to the crankshaft 9 through the connecting rod 10. An intake port 11 and an exhaust port 12 are provided in the cylinder head 4 so as to communicate with the combustion chamber 7.

  Further, the tip of the intake valve 13 is located between the intake port 11 and the combustion chamber 7, and the tip of the exhaust valve 14 is located between the exhaust port 12 and the combustion chamber 7. An intake camshaft 15 having a cam 15a and an exhaust camshaft 16 having a cam 16a are provided in a cam chamber surrounded by the cylinder head 4 and a head cover (not shown).

  The intake camshaft 15 has a cam 15a in contact with the other end of the intake valve 13, and rotates the intake valve 13 in the vertical direction by rotating. Thereby, the intake valve 13 opens and closes between the intake port 11 and the combustion chamber 7. The cam 16a is in contact with the other end of the exhaust valve 14, and the exhaust cam shaft 16 moves the exhaust valve 14 in the vertical direction by rotating. Thereby, the exhaust valve 14 opens and closes between the exhaust port 12 and the combustion chamber 7.

  The cylinder head 4 is provided with a spark plug 17 so that the tip is located in the combustion chamber 7. Then, the air-fuel mixture flowing into the combustion chamber 7 through the intake port 11 is ignited and burned at the spark plug 17 at a predetermined timing. By such combustion, the piston 6 reciprocates, and the reciprocating motion is converted into the rotational motion of the crankshaft 9 through the connecting rod 10.

  An intake pipe 18 is attached to the opening of the intake port 11 in the outer wall surface of the cylinder head 4. An intake passage 19 through which intake air is guided is formed inside the intake pipe 18, and the intake passage 19 and the intake port 11 communicate with each other.

  A partition wall 20 is disposed inside the intake port 11. The partition wall 20 has a plate-shaped main body portion 20 a, and the main body portion 20 a extends from the inside of the intake port 11 to the inside of the intake flow path 19. The main body 20a divides the downstream side of the intake flow path 19 and the upstream side of the intake port 11 into the vertical direction in FIG. 1 along the flow direction of the intake air, and the first flow path 21 and the second flow path 22 are divided. Form. That is, a part of each of the intake flow path 19 and the intake port 11 is divided into the first flow path 21 and the second flow path 22 by the partition wall 20.

  Further, the partition wall 20 is arranged to be deviated downward in FIG. 1 from the center of the intake flow path 19 and the intake port 11, and the upper first flow path 21 partitioned by the partition wall 20 has a lower side. The flow path is wider than the second flow path 22. A TGV (Tumble Generation Valve) 23 is disposed on the upstream side of the partition wall 20 in the intake passage 19 and opens and closes the first passage 21.

  FIG. 2 is an explanatory diagram for explaining the tumble flow. In FIG. 2, the one-dot chain line arrow indicates the flow of intake air. As shown in FIG. 2, when the opening of the TGV 23 is minimized and the first flow path 21 is closed by the valve body 23 a of the TGV 23, the intake air guided to the intake flow path 19 passes through the second flow path 22. To the combustion chamber 7.

  The intake air that has flowed into the combustion chamber 7 travels along the cylinder bore 5 toward the upper surface of the piston 6 and then flows along the upper surface of the piston 6 toward the left side (the intake port 11 side) in FIG. Then, it flows along the cylinder bore 5 toward the cylinder head 4. Thus, in the engine 1, the intake air forms a longitudinal vortex (tumble flow) in the combustion chamber 7.

  For example, when the load on the engine 1 is small and the intake flow rate is small, the opening degree of the first flow path 21 is reduced, and most of the intake air is passed to the second flow path 22 side. The tumble flow is strengthened by flowing the intake air with an increased flow velocity into the combustion chamber 7, and when the tumble collapse occurs due to the compression in the combustion chamber 7 by the piston 6, the gas flow in the combustion chamber 7 is disturbed. Becomes larger. At this time, the fuel mixture is ignited by the spark plug 17 to realize rapid combustion of the fuel, thereby improving fuel consumption and combustion stability.

  FIG. 3 is a first view for explaining the tumble flow measuring device 100. FIG. 3A shows a portion of the cylinder head 4 which is the inner wall of the combustion chamber 7 as viewed from the piston 6 side. FIG. 3B shows a virtual plane A perpendicular to the flow direction of the tumble flow in the combustion chamber 7. The virtual plane A is a position in the vicinity of the spark plug 17 in the combustion chamber 7 as indicated by a broken line in FIG. 2, for example. In FIG. 3B, the vertical direction (the direction indicated by the arrow B) is parallel to the vertical direction in FIG. 3A, that is, the arrangement direction of the two openings of the intake port 11.

  The intake port 11 and the exhaust port 12 are branched inside the cylinder head 4, and two openings facing the combustion chamber 7 are arranged in parallel in the vertical direction in FIG. Since two openings on the combustion chamber 7 side of the intake port 11 are arranged side by side, the tumble flow formed by flowing into the combustion chamber 7 from the two openings of the intake port 11 (in FIG. 3B, the tumble flow). As shown in FIG. 3 (b), the main passage range of the flow is indicated by a one-dot chain line, and a tumble flow is formed in the virtual plane A extending in the arrangement direction (parallel direction) of the two openings of the intake port 11. Is done.

  In order to measure the flow velocity distribution of the tumble flow, the tumble flow measuring device 100 is used. The tumble flow measuring device 100 includes a first probe 110, a second probe 112, a third probe 114, a control unit 116, and an evaluation unit 118.

  The first probe 110, the second probe 112, the third probe 114, and the control unit 116 constitute a laser Doppler velocimeter (LDV) and measure the gas flow velocity in the combustion chamber 7. The first probe 110, the second probe 112, and the third probe 114 are accommodated in the accommodating holes 4a, 4b, and 4c provided in the cylinder head 4, respectively.

  FIG. 4 is a second view for explaining the tumble flow measuring device 100. FIG. 4 is a cross-sectional view of the tumble flow measuring device 100, the cylinder block 2 and the cylinder head 4 taken along the line IV-IV in FIG. 6a is a cross section parallel to the axis 6a. In FIG. 4, the piston 6 is located at the top dead center.

  As shown in FIG. 4, the accommodation holes 4 a, 4 b and 4 c penetrate from the upper surface 4 d of the cylinder head 4 to the combustion chamber 7. A spark plug 17 is disposed in the accommodation hole 4 a together with the first probe 110. The first probe 110 is disposed adjacent to the spark plug 17. The second probe 112 is disposed in the accommodation hole 4b, and the third probe 114 is disposed in the accommodation hole 4c.

  The tips of the first probe 110, the second probe 112, and the third probe 114 are opposed to the combustion chamber 7, respectively. Then, the first probe 110, the second probe 112, and the third probe 114 project a pair of laser beams having high coherence from the tip into the combustion chamber 7, and the first measurement position a, the second measurement position b, and the third probe light. Scattered light from the tracer particles contained in the intake air passing through the interference fringes generated at the measurement position c is received. Here, the tracer particles may be mixed in the intake air for measurement, or the fuel injected into the intake air may be used as the tracer particles.

  The control unit 116 controls the emission of laser light from the first probe 110, the second probe 112, and the third probe 114 to the combustion chamber 7, and the first probe 110, the second probe 112, and the third probe 114 receive the light. From the scattered light, the gas flow velocity at the first measurement position a, the second measurement position b, and the third measurement position c is calculated.

  Here, the first measurement position a is in the vicinity of the tip of the spark plug 17 and is located in a predetermined range including the center of the tumble flow on the virtual plane A shown in FIG. Further, the second measurement position b is located in the left-right direction (the direction in which the two openings of the intake port 11 are arranged) in FIG. 4 with respect to the first measurement position. The third measurement position c is located on the opposite side of the second measurement position b across the first measurement position a in the left-right direction in FIG.

  Here, the first measurement position a, the second measurement position b, and the third measurement position c are approximately equal in the vertical direction (stroke direction of the piston 6) in FIG. And the two openings of the exhaust port 12. The first measurement position a, the second measurement position b, and the third measurement position c are located in the same plane (a plane perpendicular to the flow direction of the tumble flow), and more specifically, on the same straight line in the plane. Located in.

  The first measurement position a, the second measurement position b, and the third measurement position c are closer to the cylinder head 4 than the top dead center of the piston 6. Therefore, the measurement position is not obstructed by the piston 6, and the gas flow velocity (flow velocity distribution) in all strokes of the engine 1 can be measured appropriately. Moreover, detailed evaluation of the quality of the tumble flow is possible by using the measurement result. This quality evaluation will be described later.

  The evaluation unit 118 acquires the measurement result of the gas flow rate from the control unit 116, and calculates a value serving as an index for evaluating the tumble flow.

  FIG. 5 is a diagram illustrating an example of tumble flow evaluation. In FIG. 5, the evaluation result of the tumble flow by the tumble flow measurement device 100 is shown for two engines X and Y having different shapes of the partition walls 20.

  In FIG. 5, the average flow velocities at the first measurement position a, the second measurement position b, and the third measurement position c are shown. The evaluation unit 118 divides each of the average flow velocity at the second measurement position b and the average flow velocity at the third measurement position c by the average flow velocity at the first measurement position a, and subtracts 1 from the division result to 100. To calculate the flow rate ratio (%).

  Thus, the evaluation unit 118 increases or decreases the ratio of the average flow velocity at the second measurement position b and the third measurement position c with respect to the average flow velocity at the first measurement position a, that is, the end of the combustion chamber 7 with respect to the average flow velocity at the center of the combustion chamber 7. Deviation of the average flow velocity in the vicinity of the part (flow velocity difference ratio with reference to the first measurement position a) is calculated. This calculation result becomes an index for evaluating the quality of the tumble flow. The average flow velocity and the flow velocity difference ratio at each measurement position can be output as a numerical value or a color scale from the evaluation unit 118 to a display unit (not shown) and displayed.

  For example, in the engine X, the average flow velocity at the second measurement position b is 60% higher than the average flow velocity at the first measurement position a, and the average flow velocity at the third measurement position c is equal to the average flow velocity at the first measurement position a. It was 43% higher. That is, the tumble flow of the engine X has a high flow velocity in the arrangement direction of the openings of the intake ports 11 and a low flow velocity on the center side.

  Further, in the engine Y with the improved partition wall 20, the average flow velocity at the second measurement position b is 7% higher than the average flow velocity at the first measurement position a, and the average flow velocity at the third measurement position c is the first measurement position. 3% higher than the average flow rate of a. That is, the tumble flow of the engine Y maintains a substantially uniform flow velocity in the arrangement direction of the openings of the intake ports 11.

  As a result, the turbulence intensity just before the top dead center is improved from 1.2 of engine X to 1.3 of engine Y, and the indicated fuel consumption rate (ISFC: Indicated Specific Fuel Consumption) of engine Y is The fuel consumption rate shown in the figure is improved (decreased) by 7.8%.

  From this result, in Engine Y, the secondary flow in the swirl cross section is reduced compared to Engine X, so that the quality of the tumble flow is improved. It can be said that it has improved. That is, it can be seen that the ratio of the flow velocity at the second measurement position b and the third measurement position c to the average flow velocity at the first measurement position a calculated by the evaluation unit 118 is appropriate as an index for evaluating the tumble flow.

  Thus, in the tumble flow measuring device 100, the quality of the tumble flow can be appropriately evaluated by setting the first measurement position a, the second measurement position b, and the third measurement position c in the combustion chamber 7. It becomes possible.

  FIG. 6 is a view for explaining a tumble flow measuring device 200 of a modified example, and shows a cross section of the tumble flow measuring device 200, the cylinder block 2 and the cylinder head 4 at the same positions as in FIG. In the tumble flow measuring device 100 of the above-described embodiment, the case where the accommodation holes 4 b and 4 c penetrate from the upper surface 4 d of the cylinder head 4 to the combustion chamber 7 has been described. In the tumble flow measuring device 200 of the modified example, the accommodation hole 204b penetrates from the left side surface 204d to the combustion chamber 7 in the cylinder head 4 in FIG. Further, the accommodation hole 204c penetrates from the right side surface 204e of the cylinder head 4 to the combustion chamber 7 in FIG. A second probe 212 is disposed in the accommodation hole 204b, and a third probe 214 is disposed in the accommodation hole 204c. The second probe 212 and the third probe 214 measure the gas flow velocity at the second measurement position b and the third measurement position c.

  Thus, even if the second probe 212 and the third probe 214 are accommodated in the accommodation holes 204b and 204c provided in the side surfaces 204d and 204e of the cylinder head 4, the quality of the tumble flow (flow velocity distribution) as in the above-described embodiment. ) Can be appropriately measured, and the quality of the tumble flow can be appropriately evaluated.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the embodiment and the modification described above, the case where the gas flow rate is measured by the laser Doppler velocimeter has been described. However, a measurement device other than the laser Doppler velocimeter may be used as long as the gas flow rate can be measured. However, by using a laser Doppler velocimeter, the first probe 110, the second probes 112 and 212, and the third probes 114 and 214 are arranged outside the combustion chamber 7, and the gas flow velocity inside the combustion chamber 7 is measured. Therefore, it is possible to avoid a situation in which the tumble flow is disturbed by the probe.

  In the embodiment and the modification described above, the case where the partition wall 20 and the TGV 23 are provided has been described. However, when the tumble flow is formed in the engine 1 even when the partition wall 20 and the TGV 23 are not provided. Thus, the tumble flow measuring devices 100 and 200 can appropriately measure the flow velocity distribution of the tumble flow.

  In the embodiment and the modification described above, the case where the first measurement position a, the second measurement position b, and the third measurement position c are located closer to the cylinder head 4 than the top dead center of the piston 6 has been described. However, the 1st measurement position a, the 2nd measurement position b, and the 3rd measurement position c should just be in the combustion chamber 7, for example, may be located more on the bottom dead center side.

  In this case, if the first measurement position a, the second measurement position b, and the third measurement position c are closer to the cylinder head 4 than the position of the piston 6 at the fuel ignition timing, at least the fuel ignition timing is reached in the compression stroke. Tumble flow can be measured and evaluated.

  In the embodiment and the modification described above, the first probe 110, the second probes 112 and 212, and the third probes 114 and 214 are placed in the receiving holes 4a, 4b, 4c, 204b, and 204c provided in the cylinder head 4. Although the case where it was accommodated was demonstrated, the 1st probe 110, the 2nd probes 112 and 212, and the 3rd probes 114 and 214 do not need to be provided in the cylinder head 4. FIG. For example, an accommodation hole communicating with the combustion chamber 7 may be formed in the cylinder block 2, and the first probe 110, the second probes 112 and 212, and the third probes 114 and 214 may be accommodated in the accommodation hole. However, the first probe 110, the second probes 112 and 212, and the third probes 114 and 214 are accommodated in the accommodation holes 4a, 4b, 4c, 204b, and 204c provided in the cylinder head 4, so that the first probe 110, The second probes 112 and 212 and the third probes 114 and 214 are not blocked by the piston 6. Therefore, when the first measurement position a, the second measurement position b, and the third measurement position c are changed by changing the emission angle from the first probe 110, the second probe 112, 212, and the third probe 114, 214, The degree of freedom in setting the position is improved.

  INDUSTRIAL APPLICABILITY The present invention can be used for a tumble flow measuring device and a tumble flow measuring method for measuring a flow velocity distribution of an engine tumble flow.

a First measurement position b Second measurement position c Third measurement position A Virtual plane 4 Cylinder heads 4a, 4b, 4c, 204b, 204c Accommodating hole 5 Cylinder bore 6 Piston 7 Combustion chamber 11 Intake port 100, 200 Tumble flow measuring device 110 First probe 112, 212 Second probe 114, 214 Third probe 118 Evaluation section

Claims (6)

A gas at a first measurement position set in a predetermined range including the center of the tumble flow in a virtual plane perpendicular to the flow direction of the tumble flow among the combustion chambers surrounded by the cylinder bore, the cylinder head, and the piston A first probe for measuring the flow velocity;
A second probe for measuring a gas flow velocity at a second measurement position located in a longitudinal direction of the tumble flow in the virtual plane with respect to the first measurement position in the combustion chamber;
A third probe for measuring a gas flow rate at a third measurement position located on the opposite side of the second measurement position across the first measurement position in the longitudinal direction of the combustion chamber;
A tumble flow measuring device comprising:   2. The tumble according to claim 1, wherein the first measurement position, the second measurement position, and the third measurement position are closer to the cylinder head than a position of the piston at a fuel ignition timing. Flow measuring device.   The tumble according to claim 1 or 2, wherein the first measurement position, the second measurement position, and the third measurement position are closer to the cylinder head than the top dead center of the piston. Flow measuring device.   The tumble according to any one of claims 1 to 3, wherein the first probe, the second probe, and the third probe are accommodated in an accommodation hole provided in the cylinder head. Flow measuring device. The apparatus further comprises an evaluation index calculation unit that calculates a value to be an evaluation index of the tumble flow based on measurement results of the first probe, the second probe, and the third probe. The tumble flow measuring device according to any one of 1 to 4.   A first measurement position set in a predetermined range including the center of the tumble flow in a virtual plane perpendicular to the flow direction of the tumble flow, of the combustion chamber surrounded by the cylinder bore, the cylinder head, and the piston; A second measurement position located in the longitudinal direction of the tumble flow in the virtual plane with respect to the first measurement position in the combustion chamber, and the first measurement position in the longitudinal direction of the combustion chamber. A tumble flow measurement method, comprising: measuring a gas flow velocity at a third measurement position located on the opposite side of the second measurement position across the gap.

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