Marine low-speed diesel engine exhaust cam timing measurement tool and measurement method

Abstract

The present invention discloses a marine low-speed diesel engine exhaust cam timing measuring tool and a measuring method. The measuring tool comprises a lifting guide rod, a conical cap, a fastening rod and a position sensing mechanism; the position sensing mechanism comprises a position sensor and a positioning bracket, the position sensor is fixedly connected to the positioning bracket, and the bottom of the positioning bracket is fixed on the base of the exhaust valve actuator. The measuring method is as follows: first read the initial current value I of the analog channel on the multi-functional control panel, and at the same time calculate the change Δd of the gap between the probe of the position sensor and the conical cap before and after lifting, and obtain the output current change value ΔI of the position sensor according to Δd, rotate the main engine, and when the current value changes from the initial current value I to I+ΔI, the A angle can be obtained, and continue to rotate the main engine, and when the current value returns to I+ΔI, the B angle can be obtained. The present invention has high measurement efficiency and accurate measurement results, and can complete the timing measurement of all cylinders at one time, greatly improving the work efficiency.

Description

Technical Field

[0001] The invention relates to a diesel engine exhaust cam timing measuring tool and a measuring method, in particular to a diesel engine exhaust cam timing measuring tool and a measuring method with high measuring efficiency and capable of making full use of an existing diesel engine electronic control system for measurement, belonging to the technical field of diesel engine measuring tools. Background Art

[0002] The opening and closing angles of the exhaust cam are key parameters for diesel engine performance adjustment and emission control, and require frequent adjustments and measurements during diesel engine factory tests. Figure 1 As shown, according to the process requirements of the diesel engine, when the exhaust cam 10 rotates to angles A and B in the forward direction, the valve roller guide cylinder together with the valve drive piston is just lifted to the height position h, which is the critical position for the exhaust valve to open and close. The measurement of the exhaust cam 10 timing is to measure the A and B angles of the exhaust cam 10, where h is a constant for each engine model. The existing exhaust cam timing measurement method still uses the old mechanical measurement method, that is, manually measuring the lifting height of the exhaust cam of each cylinder, and then visually reading the crankshaft angle scale on the diesel engine flywheel to determine the exhaust cam angle. Not only is the operation cumbersome and inefficient, but the cumulative errors of manual measurement and visual readings are also large. In diesel engine factory experiments, repeated measurements and verifications are often required due to large errors, which invisibly increases the workload.

[0003] As diesel engines become more intelligent and integrated, some imported low-speed marine diesel engines are transitional models from traditional mechanical control to electrical control. These low-speed marine diesel engines are equipped with a complete electronic control system. The crankshaft angle signal has been accurately collected by the control system and has a complete human-machine interaction interface. The fuel injection is electrically controlled, but the exhaust valve opening and closing control still uses the traditional mechanical exhaust cam control. The traditional manual measurement method to measure the lifting height of the exhaust cam obviously cannot meet the needs. Summary of the invention

[0004] The purpose of the present invention is to provide a marine low-speed diesel engine exhaust cam timing measuring tool and method which has accurate measurement, high measurement efficiency and can fully utilize the existing electronic control system of the diesel engine to measure the exhaust cam lifting height.

[0005] The present invention is achieved through the following technical solutions:

[0006] A marine low-speed diesel engine exhaust cam timing measuring tool comprises a vertically arranged lifting guide rod, a conical cap with a larger upper portion and a smaller lower portion, a fastening rod and a position sensing mechanism; the lower end of the lifting guide rod is fixedly connected to a valve driving piston in an exhaust valve actuator, the conical cap is screwed and fixed on the upper end of the lifting guide rod, and the fastening rod is horizontally fixed on the top end of the lifting guide rod; the position sensing mechanism is arranged on one side of the conical cap, and comprises a position sensor and a positioning bracket, the position sensor is fixedly connected to the positioning bracket via a fastener, the probe axis of the position sensor is perpendicular to the axis of the lifting guide rod, the position sensor is connected to an analog channel on a multifunctional control panel via a signal line, and the bottom of the positioning bracket is fixed to the base of the exhaust valve actuator.

[0007] The purpose of the present invention can be further achieved by the following technical measures.

[0008] The aforementioned marine low-speed diesel engine exhaust cam timing measuring tool, wherein the positioning bracket includes a positioning plate and fixed legs symmetrically fixed on both sides of the positioning plate, the position sensor is fixedly connected to the positioning plate, and the two fixed legs are fixedly connected to the base of the exhaust valve actuator; the fixed legs are bent parts, and the center lines of the vertical sides of the two fixed legs and the center lines of the bottom sides of the two fixed legs are perpendicular to each other.

[0009] In the aforementioned marine low-speed diesel engine exhaust cam timing measuring tool, waist-shaped holes are respectively provided on the bottom edges of the two fixed legs, and the positions of the waist-shaped holes correspond to the positions of the mounting holes on the exhaust valve actuator base.

[0010] In the aforementioned marine low-speed diesel engine exhaust cam timing measuring tool, the cone angle α of the conical cap is 80° to 90°.

[0011] A measurement method using a marine low-speed diesel engine exhaust cam timing measurement tool, characterized in that it comprises the following steps:

[0012] 1) Install all parts in place, connect the position sensor to the multi-function control panel through a signal line, and read the initial current value I of the analog channel on the multi-function control panel on the computer display panel in the control room;

[0013] 2) Assume that when the valve roller guide is at the lowest point and not lifted, the initial gap between the position sensor probe and the conical cap is d1, and the gap after lifting h is d2, then the change in the gap Δd=d2-d1, and the Δd value is calculated based on the trigonometric relationship between Δd, h and the cone angle α of the conical cap;

[0014] 3) Since the measurement range of the position sensor corresponds to the output current value of the corresponding range, the two are in a linear relationship. Therefore, the output current change value of the position sensor corresponding to Δd is ΔI;

[0015] 4) Slowly rotate the main engine in the forward direction, and the exhaust cam rotates accordingly. The valve roller guide cylinder and the valve driving piston are lifted up, and the valve driving piston drives the lifting guide rod to lift up. The conical cap moves upward to generate displacement, and the position sensor sends out a current signal. At this time, read the current value of the analog channel on the multi-function control panel on the computer display panel in the control room. When the current value changes from the initial current value I to I+ΔI, the lifting height is h. Read the crankshaft angle at this time to obtain the timing angle A of the exhaust cam;

[0016] 5) Continue to rotate the main engine in the forward direction. The valve drive piston drives the lifting guide rod to continue to lift upward. When the valve drive piston reaches the top dead center, the exhaust cam continues to rotate, the valve drive piston begins to move downward, and the lifting guide rod drives the conical cap cover to move downward together. Observe the changes in the current value on the computer display panel in the control room. When the current value returns to I+ΔI, read the crankshaft angle at this time to obtain the timing B angle of the exhaust cam.

[0017] The present invention makes full use of the existing electronic control system of the diesel engine, uses a position sensor to accurately collect the lifting height of the exhaust cam, and reads the crankshaft angle through the control system according to the change of the current value on the computer display panel of the control room, thereby realizing the timing measurement of the exhaust cam. The entire measurement process is completed through the human-computer interaction interface of the control room, which is simple to operate, high in measurement efficiency, accurate in measurement results, and small in error. There is one multifunctional control panel for each cylinder. If the present invention is installed on each cylinder at the same time, the timing measurement work of all cylinders can be completed at one time, which greatly improves the work efficiency and saves manpower and material resources.

[0018] Advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments thereof, which are given by way of example only with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the timing measurement principle structure of the exhaust cam;

[0020] Figure 2 It is a schematic diagram of the structure of the present invention;

[0021] Figure 3 It is a schematic structural diagram of the conical cap of the present invention;

[0022] Figure 4 It is a structural schematic diagram of the positioning bracket of the present invention;

[0023] Figure 5 yes Figure 4 A top view of

[0024] Figure 6 It is a structural schematic diagram of the present invention in use state. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] This embodiment is described by taking the electronic control system of a ME-B type marine low-speed diesel engine imported from Germany as an example. This type of marine low-speed diesel engine requires a lifting height of h=10mm±0.1mm.

[0027] like Figure 2 and Figure 3 As shown, the present invention comprises a vertically arranged lifting guide rod 1, a conical cap 2 with a larger upper part and a smaller lower part, a fastening rod 3 and a position sensing mechanism 4. The lower end of the lifting guide rod 1 is fixedly connected to the gas valve driving piston 5 in the exhaust valve actuator through a thread, the cone angle α of the conical cap 2 is 80° to 90°, and α is 85° in this embodiment, the conical cap 2 is screwed and fixed on the upper end of the lifting guide rod 1, and the fastening rod 3 is horizontally fixed on the top of the lifting guide rod 1. The position sensing mechanism 4 is arranged on the right side of the conical cap 2, including a position sensor 41 and a positioning bracket 42, the position sensor 41 is fixedly connected to the positioning bracket 42 through a fastener, the probe axis of the position sensor 41 is perpendicular to the axis of the lifting guide rod 1, and the initial gap d1 between the probe of the position sensor 41 and the conical cap 2 is between 1.9 mm and 3.5 mm. The position sensor 41 is connected to the analog channel on the multifunctional control panel 6 through a signal line, and the bottom of the positioning bracket 42 is fixed to the base 7 of the exhaust valve actuator through a fastener.

[0028] like Figure 4 and Figure 5 As shown, the positioning bracket 42 includes a positioning plate 421 and fixed legs 422 symmetrically welded on both sides of the positioning plate 421. The position sensor 41 is fixedly connected to the positioning plate 421. The fixed legs 422 are bent parts. The center lines of the vertical edges of the two fixed legs 422 and the center lines of the bottom edges of the two fixed legs 422 are perpendicular to each other. The positioning bracket 42 can be quickly and accurately positioned on the base 7 of the exhaust valve actuator, and the verticality of the probe of the position sensor 41 and the lifting guide rod 1 can also be ensured. Waist-shaped holes 423 are respectively provided on the bottom edges of the two fixed legs 422. The positions of the waist-shaped holes 423 correspond to the positions of the mounting holes on the base 7 of the exhaust valve actuator. The two fixed legs 422 are fixedly connected to the base 7 of the exhaust valve actuator by fasteners. The positioning bracket 42 of this embodiment is suitable for models with a cylinder diameter of 350mm, 400mm and 460mm. It is ensured by the waist-shaped holes 423 on the bottom edge of the positioning bracket 42. Figure 5 As shown, D1, D2 and D3 correspond to the installation positions of 350mm, 400mm and 460mm cylinder diameters respectively.

[0029] like Figure 6 As shown, a measurement method using a marine low-speed diesel engine exhaust cam timing measurement tool comprises the following steps:

[0030] 1) Install all parts in place, connect the position sensor 41 to the multi-function control panel 7 through a signal line, and read the initial current value I of the analog channel on the multi-function control panel 7 on the computer display panel 8 in the control room;

[0031] 2) Assume that when the valve roller guide cylinder 9 is at the lowest point and not lifted, the initial gap between the probe of the position sensor 41 and the conical cap 2 is d1, and the gap after lifting h=10mm is d2, then the change in the gap Δd=d2-d1, such as Figure 3 As shown, in the right triangle, the Δd value is calculated according to the trigonometric relationship between Δd, h and the cone angle α=85° of the conical cap 2. In this embodiment, Δd≈0.8749 mm;

[0032] 3) The position sensor 41 is an inductive displacement sensor. The coil at the top of the probe emits a high-frequency current signal. The change in magnetic flux caused by the movement of the metal object will be accurately detected. Its measurement range is 0.5 to 7.5 mm, and the corresponding output current value is 4 to 16.25 mA. Since the measurement range of the position sensor 41 corresponds to the output current value of the corresponding range, the two are in a linear relationship. Based on this, it can be calculated that the output current change value of the position sensor 41 corresponding to Δd is ΔI;

[0033] 4) Slowly rotate the main engine in the forward direction, and the exhaust cam 10 rotates accordingly. The valve roller guide cylinder 9 and the valve driving piston 5 are lifted up, and the valve driving piston 5 drives the lifting guide rod 1 to lift up, and the conical cap 2 moves upward to generate displacement, and the position sensor 41 sends out a current signal. At this time, the current value of the analog channel on the multi-function control panel 6 is read on the computer display panel 8 in the control room. When the current value changes from the initial current value I to I+ΔI, the lifting height is h. The crankshaft angle at this time is read to obtain the timing angle A of the exhaust cam 10;

[0034] 5) Continue to rotate the main engine in the forward direction. The valve drive piston 5 drives the lifting guide rod 1 to continue to lift upward. When the valve drive piston 5 reaches the top dead center, the exhaust cam 10 continues to rotate, the valve drive piston 5 begins to move downward, and the lifting guide rod 1 drives the conical cap 2 to move downward together. Observe the change of the current value on the computer display panel 8 in the control room. When the current value returns to I+ΔI, read the crankshaft angle at this time to obtain the timing B angle of the exhaust cam 10.

[0035] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A measurement method using a marine low-speed diesel engine exhaust cam timing measurement tool, the marine low-speed diesel engine exhaust cam timing measurement tool comprising a vertically arranged lifting guide rod, a conical cap with a larger upper portion and a smaller lower portion, a fastening rod and a position sensing mechanism; the lower end of the lifting guide rod is fixedly connected to the valve driving piston in the exhaust valve actuator, the conical cap is screwed and fixed on the upper end of the lifting guide rod, and the fastening rod is horizontally fixed on the top of the lifting guide rod; the position sensing mechanism is arranged on one side of the conical cap, and comprises a position sensor and a positioning bracket, the position sensor is fixedly connected to the positioning bracket through a fastener, and the probe axis of the position sensor is aligned with the lifting guide rod. The rod axis is vertical, the position sensor is connected to the analog channel on the multi-function control panel through a signal line, and the bottom of the positioning bracket is fixed on the base of the exhaust valve actuator; the positioning bracket includes a positioning plate and fixed legs symmetrically fixed on both sides of the positioning plate, the position sensor is fixedly connected to the positioning plate, and the two fixed legs are fixedly connected to the base of the exhaust valve actuator; the fixed legs are bent parts, and the center lines of the vertical sides of the two fixed legs and the center lines of the bottom sides of the two fixed legs are perpendicular to each other; waist-shaped holes are respectively provided on the bottom sides of the two fixed legs, and the positions of the waist-shaped holes correspond to the positions of the mounting holes on the base of the exhaust valve actuator; it is characterized in that, The following steps are involved: 1) Install all parts in place, connect the position sensor to the multi-function control panel through a signal line, and read the initial current value I of the analog channel on the multi-function control panel on the computer display panel in the control room; 2) Assume that when the valve roller guide is at the lowest point and not lifted, the initial gap between the position sensor probe and the conical cap is d1, and the gap after lifting h is d2, then the change in the gap Δd=d2-d1, and the Δd value is calculated based on the trigonometric relationship between Δd, h and the cone angle α of the conical cap; 3) Since the measurement range of the position sensor corresponds to the output current value of the corresponding range, the two are in a linear relationship. Therefore, the output current change value of the position sensor corresponding to Δd is ΔI; 4) Slowly rotate the main engine in the forward direction, and the exhaust cam rotates accordingly. The valve roller guide cylinder and the valve driving piston are lifted up, and the valve driving piston drives the lifting guide rod to lift up. The conical cap moves upward to generate displacement, and the position sensor sends out a current signal. At this time, read the current value of the analog channel on the multi-function control panel on the computer display panel in the control room. When the current value changes from the initial current value I to I+ΔI, the lifting height is h. Read the crankshaft angle at this time to obtain the timing angle A of the exhaust cam; 5) Continue to rotate the main engine in the forward direction. The valve drive piston drives the lifting guide rod to continue to lift upward. When the valve drive piston reaches the top dead center, the exhaust cam continues to rotate, the valve drive piston begins to move downward, and the lifting guide rod drives the conical cap cover to move downward together. Observe the changes in the current value on the computer display panel in the control room. When the current value returns to I+ΔI, read the crankshaft angle at this time to obtain the timing B angle of the exhaust cam.

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