Manufacturing method of cylinder block for outboard engine

Abstract

To provide a manufacturing method of a cylinder block for an outboard engine which enables a worker to monitor sealability of elastic bag bodies on a steady basis even when the temperature changes through a series of treatment processes and influence of the temperature change causes the elastic bag bodies to repeat slight expanding and contracting.SOLUTION: Cylinder block main parts 10 are attached to a transport jig 20 including pressure gauges 22 for detecting gas pressures of elastic bag bodies, and a support plate 30 including an elastic jig is attached to each cylinder block main part 10. The elastic jig supplies a gas to expand the elastic bag bodies, thereby pressing ends, at which a base material is exposed, of an inner peripheral surface of a cylinder bore of each cylinder block main part 10, and anodic oxidation treatment and sealing treatment are performed in a state that the ends are pressed in the above-described manner. When these treatments are performed with the ends pressed, while the transport jig 20 moves the cylinder block main parts 10 to a processing tank of the anodic oxidation treatment and a processing tank of the sealing processing and move up or down the cylinder block main parts 10 to immerse them in the tanks sequentially, gas pressures detected by the pressure gauges 22 are monitored.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a cylinder block for an outboard motor. [Background technology]

[0002] In industrial internal combustion engines, cooling water is circulated to maintain performance and control the temperature of the engine. The cooling water typically used in automobiles contains water with additives such as ethylene glycol, and if the amount of water decreases, it must be replenished. On the other hand, engines such as outboard motors use seawater (salt water), which is readily available in the operating environment, as cooling water.

[0003] However, because outboard motor components are made of many different metallic materials, potential differences arise between the metallic materials of the components in contact with seawater. Metallic materials with low natural potentials dissolve in seawater, potentially causing corrosion. Aluminum alloys, particularly those used in outboard motor cylinder blocks, are more susceptible to corrosion than other materials. Therefore, anodizing treatment and subsequent sealing treatment are known for aluminum alloys. Outboard motor cylinder blocks have a cylindrical cast-iron cylinder sleeve cast into the aluminum alloy base material on the inner periphery of the cylinder bore. Immersing the entire cylinder block in an anodizing solution for this type of cylinder block can dissolve the cast iron of the cylinder sleeve, resulting in pitting corrosion.

[0004] In order to perform anodizing and subsequent sealing without dissolving the cast iron of the cylinder sleeve, Patent Document 1 discloses a method for manufacturing an outboard motor cylinder block that includes a step of pressing, with an elastic jig, an area encompassing the boundary between the cast iron of the cylinder sleeve and the aluminum alloy base material of the cylinder block body. Patent Document 1 also describes a method in which the elastic jig is an elastic bag equipped with a gas supply unit that is placed in the cylinder bore and gas is supplied from the gas supply unit to inflate the elastic bag, thereby pressing the area encompassing the boundary with the elastic bag. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-1587 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the temperature fluctuates during the series of processing steps, including anodizing and sealing, and the elastic bag inflated with gas is affected by this and repeatedly expands and contracts slightly, so it was desirable to be able to constantly monitor the sealing ability of the elastic bag against the inner surface of the cylinder sleeve.

[0007] In view of the above problems, the present invention aims to provide a method for manufacturing an outboard motor cylinder block that can constantly monitor the sealing performance of an elastic bag, even when the temperature fluctuates during a series of processing steps and the elastic bag repeatedly expands and contracts slightly due to this influence. [Means for solving the problem]

[0008] In order to achieve the above object, a method of manufacturing an outboard motor cylinder block according to the present invention includes the steps of: attaching one or more outboard motor cylinder block bodies to a transport jig; attaching an elastic jig to the outboard motor cylinder block body attached to the transport jig; and attaching an elastic bag body connected to a gas supply unit to the elastic jig. The elastic jig attaches an elastic bag body to the outboard motor cylinder block body, the elastic bag body being attached to the transport jig. The elastic jig attaches an elastic bag body connected to a gas supply unit to the outboard motor cylinder block body. the step of supplying gas from the gas supply unit to inflate the elastic bag body to press against the ends of the inner circumferential surface of the cylinder bore where the base material is exposed on the cylinder head side and the crankshaft side; the step of performing anodizing treatment while the elastic jig is pressing the end of the elastic bag body, where the base material is exposed on the cylinder head side and the crankshaft side, to form an anodized film on the surface of the aluminum alloy portion of the outboard motor cylinder block body other than the cylinder bore; and the step of performing a sealing treatment while the elastic jig is pressing the end of the elastic bag body to seal the surface of the anodized film, to seal the surface of the anodized film, the transport jig having a pressure gauge that detects the gas pressure in the elastic bag body, and the gas pressure detected by the pressure gauge is monitored while the transport jig is moving and raising and lowering the one or more outboard motor cylinder block bodies to be successively immersed in the anodizing treatment tank and the sealing treatment tank. [Effects of the Invention]

[0009] According to the present invention, the gas pressure detected by the pressure gauge is monitored while the transport jig moves the cylinder block body into the treatment tank for a series of treatment processes and raises and lowers it to successively immerse it, thereby making it possible to constantly monitor the sealing ability of the elastic bag body even when the elastic bag body repeatedly expands and contracts slightly. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a perspective view of the cylinder head side of an example of an outboard motor cylinder block body that is the subject of surface treatment in a manufacturing method for an outboard motor cylinder block according to the present invention. FIG. [Figure 2] 1 is a front view showing a transport jig and an outboard motor cylinder block body for illustrating a preferred embodiment of a method for manufacturing an outboard motor cylinder block according to the present invention; [Figure 3] 1 is a front view showing a transport jig and an outboard motor cylinder block body for illustrating a preferred embodiment of a method for manufacturing an outboard motor cylinder block according to the present invention; [Figure 4] 4 is a cross-sectional side view showing the support plate and the outboard motor cylinder block body shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing an outboard motor cylinder block according to the present invention will now be described with reference to the accompanying drawings.

[0012] The manufacturing method for an outboard motor cylinder block in this embodiment includes the steps of attaching one or more cylinder block bodies to a transport jig, attaching an elastic jig equipped with an elastic bag body to the cylinder block body attached to the transport jig, inflating the elastic bag body by supplying gas to press against the ends of the inner surface of the cylinder bore of the cylinder block body where the base material is exposed on the cylinder head side and the crankshaft side, an anodizing treatment step of anodizing the ends while the end ends are pressed, thereby forming an anodized film on the surface of the aluminum alloy portion of the cylinder block body, and a sealing treatment step of sealing the anodized film by performing a sealing treatment while the end ends are pressed.

[0013] First, we will explain the cylinder block body, which is the target of the anodizing and sealing treatments in this method. As shown in Figure 1, a cylinder block body 10 has a joining surface 14 where it is joined to a cylinder head (not shown), and multiple cylinder bores 11 and a water jacket 15 formed around these cylinder bores 11. Note that this figure shows the cylinder block body 10 with three cylinder bores 11 aligned horizontally, but in an actual outboard motor (not shown), the cylinder block body 10 is mounted with the cylinder bores 11 aligned vertically. Also, the number of cylinder bores 11 may be one for a single-cylinder engine.

[0014] This cylinder block body 10 is attached to a transport jig 20 as shown in FIG. 2. The transport jig 20 has a pressure adjustment unit 21 at the top and a hanging unit 24 at the bottom in the vertical direction. The pressure adjustment unit 21 is connected to a gas supply source (not shown) via a main gas supply pipe 23. The main gas supply pipe 23 is provided with, in order from the gas supply source side, a pressure adjustment valve 41, a disconnection pressure on-off valve 42, and four pressure on-off valves 43. The disconnection pressure on-off valve 42 is disposed at the inlet of the transport jig 20, and the main gas supply pipe 23 between the pressure adjustment valve 41 and the disconnection pressure on-off valve 42 is detachably connected. The four pressure on-off valves 43 are disposed in parallel with the main gas supply pipe 23, and a pressure gauge 22 is further provided on the outlet side of each pressure on-off valve 43.

[0015] Each pressure gauge 22 is equipped with a wireless device (not shown), and each transmitter is connected to a receiver (not shown) so as to be able to communicate wirelessly. The receiver displays the measured gas pressure values ​​detected by each pressure gauge 22 in real time. It can also record them chronologically. This allows the worker to easily monitor the gas pressure values ​​from a remote location without having to move with the transport jig 20. The receiver is placed in a location where a person can monitor, and outputs an alarm if the measured gas pressure value detected by the pressure gauge 22 falls below the lower threshold. This allows air leaks to be detected early and prompt action to be taken.

[0016] The hanging part 24 has three horizontal members 26 arranged in the vertical direction, and is configured so that the cylinder block body 10 is attached between the horizontal members 26. The pressure adjustment part 21 and the hanging part 24 are fixed with connecting members 25. The transport jig 20 is raised and lowered to immerse the cylinder block body 10 in a treatment tank for anodizing (not shown) and a treatment tank for sealing (not shown). On the transport jig 20, the pressure gauge 22 is positioned so that it is not immersed in either treatment tank, and thus the pressure adjustment part 21 is positioned above the hanging part 24 to which the cylinder block body 10 is attached. This makes it possible to prevent the pressure gauge 22 from being splashed with treatment liquid.

[0017] The cylinder block body 10 is attached to a horizontal member 26 from above and below using fixing members 27a, 27b. The horizontal member 26 is conductive and also functions as an anode bus bar. For anodizing the cylinder block body 10, two screw holes (not shown) in the cylinder block body 10 are fastened to the anode bus bar (horizontal member 26) with bolts 28. This allows electricity to be passed through the cylinder block body 10 during the anodizing process. The two screw holes are preferably located at the same height on the transport jig 20.

[0018] Next, as shown in Figures 3 and 4, an elastic jig 32 is attached to each cylinder block body 10. If the cylinder block body 10 has multiple cylinder bores 11, the same number of elastic jigs 32 are used to attach them to the cylinder bores 11. To easily attach multiple elastic jigs 32 in this way, a support plate 30 is used to support the same number of elastic jigs 32 as the cylinder bores 11. The support plate 30 is provided with elastic jigs 32 at intervals that are the same as the intervals between the cylinder bores 11 in the cylinder block body 10. In addition, each support plate 30 is provided with gas supply pipes 29 that supply gas from the pressure gauge 22 to the elastic jigs 32.

[0019] As shown in FIG. 4, the elastic jig 32 may include two elastic bags 33a and 33b that can be expanded and contracted by supplying gas. One elastic bag 32a can press against the end of the inner circumferential surface of the cylinder bore 11 where the base material is exposed on the cylinder head side, and the other elastic bag 32b can press against the end of the inner circumferential surface of the cylinder bore 11 where the base material is exposed on the crankshaft side. In this case, the elastic jig 32 includes a gas passage 34 that fluidly connects the two elastic bags 33a and 33b, allowing both elastic bags 33a and 33b to be inflated simultaneously. As the elastic bags, for example, a commercially available jig known as an air picker, which has an elastic bag portion that can be expanded and contracted by gas pressure, can be used.

[0020] The support plate 30 is equipped with positioning bosses 31 for the cylinder block body 10. The positioning bosses 31 have a predetermined length and are arranged at the four corners of the support plate 30 so as to maintain a predetermined distance between the support plate 30 and the joint surface 14 of the cylinder block body 10 where the cylinder head is joined. This makes it possible to easily attach the elastic jig 32 to a predetermined position in the cylinder bore 11 as described above, and also makes it easy to remove it after the series of steps have been completed, improving work efficiency.

[0021] 2 and 3 show a case where four cylinder block bodies 10 are attached to the transport jig 20, but the present invention is not limited to this. The transport jig 20 may be capable of attaching one cylinder block body 10, or may be capable of attaching a plurality of cylinder block bodies 10 other than four. The transport jig 20 is equipped with the same number of pressure gauges 22 and gas supply pipes 29 as the number of cylinder block bodies 10 to be attached. This allows the gas pressure in the elastic jig 32 for each cylinder block body 10 to be monitored with the pressure gauge 22, making it possible to quickly identify a cylinder block body 10 that has an air leak and take prompt action.

[0022] Once the elastic jig 32 has been attached to each cylinder block body 10 in this manner, gas is supplied to the elastic jig 32 from the gas supply source via the main gas supply pipe 23 and gas supply piping 29. The elastic bags 33a, 33b of the elastic jig 32 of each cylinder block body 10 are inflated to a predetermined gas pressure using the pressure adjustment valve 41 and pressure on-off valve 43. This allows the elastic bags to press against both ends of the inner circumferential surface of the cylinder bore 11 of the cylinder block body 10, one on the cylinder head side and one on the crankshaft side. It is preferable to press against the regions of the inner circumferential surface of the cylinder bore 11 of the cylinder block body 10, which include the boundary between the cast iron and the aluminum alloy, on the cylinder head side and the crankshaft side.

[0023] After the measured gas pressure values ​​sent from each pressure gauge 22 via the radio are confirmed by the receiver, the pressure regulating valve 41 and the isolation pressure on-off valve 42 are closed to disconnect the pressure regulating valve 41 from the isolation pressure on-off valve 42. Then, with the elastic bags 33a, 33b attached to the cylinder block 11 while maintaining a predetermined gas pressure, the transport jig 20 is moved and the anodizing process is carried out.

[0024] In the anodizing process, the transport jig 20 is raised and lowered to immerse the cylinder block bodies 10 attached to the hanging portion 24 of the transport jig 20 in an anodizing treatment bath. An electrolytic treatment is then performed to form a porous anodized film on the surface of each cylinder block body 10. Inside the treatment bath, the aluminum alloy that is the base material of the cylinder block bodies 10 melts, and the molten aluminum combines with oxygen in the treatment liquid to form an anodized aluminum oxide film on the surface of the aluminum alloy portion of the cylinder block body 10. Meanwhile, the inner circumferential surface of the cylinder bore 11 is covered by the elastic bags 33a and 33b, preventing it from coming into contact with the treatment liquid and preventing the dissolution of the cast iron of the cylinder sleeve.

[0025] Next, the transport jig 20 is moved, and the sealing treatment step is performed. The transport jig 20 is raised and lowered to immerse the cylinder block body 10 attached to the hanging part 24 of the transport jig 20 in a sealing treatment bath. The pores in the porous anodic oxide film formed on the surface of the cylinder block body 10 are sealed, improving the corrosion resistance of the anodic oxide film. The sealing treatment step can be performed using known methods such as a hydrothermal method, a boiling water method, a nickel acetate method, or a lithium hydroxide method.

[0026] Once all the treatment steps are completed, the gas pressure is released and the elastic jig 32 is removed from the cylinder block body 10. Note that degreasing and water washing may be performed as pretreatment before the anodizing treatment step. Water washing may also be performed between the anodizing treatment step and the sealing treatment step. This prevents the adhering anodizing treatment liquid from mixing with the sealing treatment liquid and also removes the treatment liquid remaining in the pores of the anodized film. Furthermore, water washing and hot water washing may be performed after the sealing treatment step.

[0027] The temperature of the cylinder block body 10 fluctuates as it undergoes these treatment steps. For example, in the above treatment order, degreasing is performed at approximately 40 to 50°C, water rinsing at room temperature, anodizing at approximately 5 to 20°C, water rinsing at room temperature, sealing at 40 to over 90°C, water rinsing at room temperature, and hot water rinsing at approximately 50°C. The elastic bags 33a, 33b inflated with gas repeatedly expand and contract minutely due to the gas. Therefore, a pressure gauge 22 is provided on the transport jig 20 to detect the gas pressure of the elastic bags 33a, 33b. By monitoring the gas pressure detected by the pressure gauge 22 while the transport jig 20 moves the cylinder block body through the treatment baths for the above steps and raises and lowers it to successively immerse it, the sealing ability of the elastic bags 33a, 33b can be constantly monitored, even when the elastic bags 33a, 33b repeatedly expand and contract.

[0028] Furthermore, by subjecting the cylinder block body to the steps of attaching it to a transport jig, attaching an elastic jig, pressing, anodizing, and sealing, it is possible to manufacture a cylinder block for an outboard motor having a sealed anodized coating on the aluminum alloy portion of the cylinder block without dissolving the cast iron of the cylinder sleeve. In particular, the joining surface 14 of the cylinder block and the inner surface of the water jacket 15 are close to the combustion chamber, are exposed to high temperatures, and are likely to come into contact with cooling water (seawater), making them prone to corrosion. Therefore, forming a sealed anodized coating on the cylinder block for an outboard motor can prevent corrosion. [Example]

[0029] A cast-in cylinder sleeve made of cast iron was prepared, and a cylinder block was fabricated by casting the cast-in cylinder sleeve into an aluminum alloy ADC12. It was confirmed that boundaries between the cast iron and the aluminum alloy were formed on the inner peripheral surface of the cylinder bore at the end on the cylinder head side and the end on the crankshaft side.

[0030] Next, the four cylinder blocks were attached to a transport jig equipped with four gas supply pipes, four pressure gauges, and four radios. An elastic jig was then attached to each cylinder block. Two air pickers were inserted into the cylinder bore at the end on the cylinder head side and the end on the crankshaft side, at positions that pressed against the area encompassing the boundary between the cast iron and aluminum alloy. The air pickers were then inflated to a predetermined gas pressure via the gas supply pipes from an air supply center equipped with a pressure regulating valve.

[0031] After checking the gas pressure measurements sent from each pressure gauge via a radio on a receiver, the pressure regulating valve and the isolation pressure valve installed on the transport jig's main gas supply pipe were closed, separating the pressure regulating valve from the isolation pressure valve. Then, with the elastic jig attached to the cylinder block, the transport jig was moved, and the cylinder block was raised and lowered into each treatment tank in the following order: degreasing, water washing, anodizing, water washing, sealing, water washing, and hot water washing. The anodizing treatment was performed using direct current electrolysis, immersing the cylinder block in a sulfuric acid bath with a temperature of 20°C and a concentration of 200 g / L, with a current density of 1.5 A / dm 2 A voltage was applied for 20 minutes.

[0032] After washing with hot water, the air pressure of the air picker was reduced, the air picker was removed from the cylinder bore, and the inner surface of the cylinder bore of the cylinder block was observed. Also, while each process was being carried out, the gas pressure of the air picker of the four cylinder blocks was monitored with a receiver. The gas pressure at that time (kg / cm 2 The measurement results are shown in Table 1.

[0033] [Table 1]

[0034] Observation of the cylinder block revealed that a 5-15 μm thick anodized film had formed on the areas other than the cylinder bore. There was no evidence that the cast iron cylinder sleeve had come into contact with the anodizing treatment liquid on either the cylinder head or crankshaft side, and no dissolution or pitting of the cast iron was confirmed.

[0035] Furthermore, as shown in Table 1, although there was a slight delay in pressure fluctuations in response to temperature changes, it was possible to constantly grasp the pressure in each treatment tank in real time. Therefore, it was confirmed that by constantly checking the pressure, it was possible to ensure the sealing performance of each cylinder block. [Explanation of symbols]

[0036] 10 Cylinder block body 11 Cylinder bore 12 Cylinder sleeve (cast iron) 13 Base material (aluminum alloy) 14 Cylinder head interface 15 Water Jacket 20 Transport jig 21 Pressure adjustment section 22 Pressure gauge 23 Gas supply main 24 Hanging part 25 Connecting material 26 Horizontal member 27a, 27b fixing members 28 volts 29 Gas supply piping 30 Support Plate 31 Positioning boss 32 Elastic jig 33a, 33b Elastic bag body 34 Gas passage 41 Pressure Regulating Valve 42 Pressure shut-off valve for isolation 43 Pressure shut-off valve

Claims

1. A method of manufacturing an outboard motor cylinder block, comprising: An outboard motor cylinder block body has a cylinder bore and a water jacket formed around the cylinder bore at a joining surface where the cylinder head is joined, a cylindrical cylinder sleeve made of cast iron is cast-inserted into an aluminum alloy base material on the inner circumferential surface of the cylinder bore, and the base material is exposed at the end of the inner circumferential surface of the cylinder bore on the cylinder head side and the opposite end on the crankshaft side, attaching one or more of the outboard motor cylinder block bodies to a transport jig; a step of attaching an elastic jig to the outboard motor cylinder block body attached to the transportation jig; the elastic jig includes an elastic bag connected to a gas supply unit, and gas is supplied from the gas supply unit to inflate the elastic bag, thereby pressing the ends of the inner circumferential surface of the cylinder bore on the cylinder head side and the crankshaft side where the base material is exposed; performing anodizing treatment while being pressed by the elastic jig to form an anodized film on the surface of the aluminum alloy portion of the cylinder block body for outboard motors other than the cylinder bores; a step of performing a sealing treatment while being pressed by the elastic jig to seal the surface of the anodized coating; Including, a transporting jig equipped with a pressure gauge for detecting the gas pressure of the elastic bag body, and monitoring the gas pressure detected by the pressure gauge while the transporting jig moves and raises and lowers the one or more outboard motor cylinder block bodies into the anodizing treatment tank and the sealing treatment tank, successively immersing them.

2. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the pressure gauge is disposed above the one or more outboard motor cylinder block bodies attached to the transport jig and at a position where the pressure gauge is not immersed in the anodizing treatment tank or the sealing treatment tank even when the transport jig is raised or lowered.

3. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the pressure gauge includes a transmitter, and a measured value of the detected gas pressure is displayed on a receiver capable of wireless communication with the transmitter.

4. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the receiver outputs an alarm when the measured value of the gas pressure detected by the pressure gauge falls below a lower threshold value.

5. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the transport jig is provided with the same number of pressure gauges as the number of outboard motor cylinder block bodies attached to the transport jig, and the gas pressure is monitored by the pressure gauge for each of the outboard motor cylinder block bodies.

6. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the gas supply unit includes a detachable on-off valve, and after the pressing step and before the anodizing step, the detachable on-off valve is closed to detach the gas supply unit from the transport jig.

7. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein the outboard motor cylinder block body has a plurality of cylinder bores, and the step of attaching the elastic jigs is carried out using a support plate that supports the same number of elastic jigs as the cylinder bores and that has positioning bosses for positioning relative to the outboard motor cylinder block body.

8. 2. The method for manufacturing an outboard motor cylinder block according to claim 1, wherein two screw holes in the outboard motor cylinder block body are fastened to an anode bus bar provided on the transport jig by bolts, and electricity is applied to the outboard motor cylinder block body.

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