Oil-cooled four-stroke engine for powered paragliders

Abstract

An oil-cooled four-stroke engine for a power parachute includes an engine body, a parachute fixing frame, an engine oil cooler and an oil cooling pipe assembly. The engine body is provided with an oil passage. The parachute fixing frame is arranged on one side of the engine body. The engine oil cooler is fixed on the parachute fixing frame. The oil cooling pipe assembly connects the engine oil cooler and the oil passage of the engine body. Thus, the oil cooling pipe assembly can guide the engine oil cooled by the engine oil cooler into the engine body, achieving the effects of cooling and lubrication, greatly reducing the weight of the oil-cooled four-stroke engine, and lowering the load of the user and fuel consumption.

Description

TECHNICAL FIELD

[0001] The present invention relates to a four-stroke engine, in particular, a four-stroke engine for a power parachute. BACKGROUND

[0002] A power parachute is a kind of flying parachute which is used in combination with a propeller engine, and is widely used in the field of aviation sports because it can achieve sustained flight by the thrust provided by the propeller engine.

[0003] Referring to Figure 7 , it is a water-cooled four-stroke engine 60 which can be used as a propeller engine, and the displacement of the water-cooled four-stroke engine 60 is 250 c.c. The water-cooled four-stroke engine 60 includes a water tank 61, an engine body 62, a cold water pipe 63, and a hot water pipe 64. The water tank 61 is arranged and fixed to one side of the engine body 62, and includes a cooling water outlet 611 and a cooling water inlet 612. The cooling water outlet 611 and the cooling water inlet 612 of the water tank 61 are connected to the cold water pipe 63 and the hot water pipe 64, respectively. The cold water pipe 63 is connected to the engine body 62, so that the cooling water in the water tank 61 enters and cools the engine body 62. After absorbing the heat generated by the engine body 62, the cooling water exits the engine body 62 and flows back to the water tank 61 through the hot water pipe 64. In the water-cooled four-stroke engine 60, the engine body 62 is used for the flow of the cooling water, and therefore the thickness of the engine body 62 must be increased to form a water passage (not shown in the figure). As a result, Figure 7 The weight of the engine body 62 shown in the figure is as high as 18 kg. In addition, the weight of the water tank 61, the cold water pipe 63, the hot water pipe 64, and the cooling water makes the total weight of the water-cooled four-stroke engine 60 as high as 23 to 25 kg.

[0004] As can be seen from the above description, the water-cooled four-stroke engine is the power source of the power parachute. However, in order to achieve long-distance flight, the engine body must be maintained within a certain temperature range. The four-stroke engine used in the known power parachute adopts a water-cooling heat dissipation method, that is, the water tank must be externally mounted on the engine body. The water tank and the cooling water significantly increase the volume and weight of the four-stroke engine, increase the weight burden of the user during take-off and landing, and increase the fuel consumption during flight. Therefore, it is necessary to further improve it. SUMMARY

[0005] In view of the above-mentioned shortcomings of the water-cooled four-stroke engine, such as the excessive overall weight of the water-cooled four-stroke engine, which leads to an increase in the weight burden of the user and an increase in fuel consumption, the main purpose of the present invention is to provide an oil-cooled four-stroke engine for a power parachute.

[0006] In order to achieve the above-mentioned purpose, the main technical means used in the present invention is that the oil-cooled four-stroke engine for a power parachute includes:

[0007] an engine body comprising at least a crankcase, a cylinder, a cylinder head, and an oil passage, wherein the oil passage penetrates a side wall of the crankcase, the cylinder, and the cylinder head, and communicates with a camshaft chamber of the cylinder head;

[0008] a parachute fixing frame arranged at a front side of the engine body;

[0009] an oil cooler arranged at a side of the parachute fixing frame; and

[0010] an oil cooling pipe set connecting the oil cooler and the oil passage of the engine body.

[0011] As can be seen from the above description, the oil-cooled four-stroke engine for a powered parachute according to the present application forms the oil passage inside the engine body, externally mounts the oil cooler at a side of the engine body, and uses the oil cooling pipe set to connect the oil passage and the oil cooler. The oil cooling pipe set can guide the oil cooled by the oil cooler into the engine body. Since the oil passes through the crankcase, the cylinder, and the cylinder head of the engine body through the oil passage, the oil can absorb the excess heat generated by the fuel combusted in the cylinder, and can also lubricate the internal components of the engine body. Therefore, the oil-cooled four-stroke engine according to the present application does not need to use an externally mounted cooling water tank, achieves the goal of engine lightening, and reduces the weight burden of the user when taking off and landing and the consumption of fuel for flight.

[0012] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments, but is not limited to the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 : a use schematic view of a powered parachute using the oil-cooled four-stroke engine according to the present application.

[0014] Figure 2 : a perspective view of the oil-cooled four-stroke engine according to the present application.

[0015] Figure 3 : a perspective exploded view of the oil-cooled four-stroke engine according to the present application.

[0016] Figure 4A : a perspective view of a front crankcase of the oil-cooled four-stroke engine according to the present application.

[0017] Figure 4B : Figure 4A : a sectional view of an A-A section line of the oil-cooled four-stroke engine according to the present application.

[0018] Figure 5A : a perspective view of a rear crankcase of the oil-cooled four-stroke engine according to the present application.

[0019] Figure 5B FIG. 1 is a perspective view of a rear crankcase of an oil-cooled four-stroke engine according to the present invention.

[0020] Figure 5C : Figure 5A FIG. 2 is a sectional view of a B-B sectional line of the oil-cooled four-stroke engine according to the present invention.

[0021] Figure 6A : Figure 2 FIG. 3 is a partial perspective view of the oil-cooled four-stroke engine according to the present invention.

[0022] Figure 6B FIG. 4 is a partial rear perspective exploded view of the oil-cooled four-stroke engine according to the present invention.

[0023] Figure 7 FIG. 5 is a perspective view of a conventional water-cooled four-stroke engine.

[0024] In the drawings,

[0025] 1: oil-cooled four-stroke engine 2: oil tank

[0026] 3: engine frame 4: back-type parachute

[0027] 5: propeller 10: engine body

[0028] 11: crankcase 110: oil tank

[0029] 111: front crankcase 112: rear crankcase

[0030] 113: crank chamber 114: crankshaft fixing column

[0031] 115: propeller crankshaft 116: propeller transmission wheel

[0032] 117: crank assembly 118: belt

[0033] 119: piston 12: cylinder

[0034] 121: cavity 13: cylinder head

[0035] 131: camshaft chamber 132: timing inner chain gear chamber

[0036] 133: camshaft 134: combustion chamber

[0037] 135: timing chain 136: exhaust pipe

[0038] 14: oil passage 141: oil outlet

[0039] 142: oil inlet 143: first passage

[0040] 144: sub-passage 145: return passage

[0041] 146: second passage 147: oil pump

[0042] 148: inner passage 15: cover plate

[0043] 151: hot oil outlet 152: cold oil inlet

[0044] 16: screw groove 17: stud

[0045] 20: flight parachute fixing frame 21: flight parachute fixing arm

[0046] 22: cross arm 30: oil cooler

[0047] 31: cooler body 311: hot oil inlet

[0048] 312: cold oil outlet 32: front fixing sheet

[0049] 33: rear fixing sheet 40: oil cooling pipe set

[0050] 41: hot oil pipe 42: cold oil pipe

[0051] 60: water-cooled four-stroke engine 61: water tank

[0052] 611: cooling water outlet 612: cooling water inlet

[0053] 62: engine body 63: cold water pipe

[0054] 64: hot water pipe DETAILED DESCRIPTION

[0055] The structural principle and working principle of the present application will be described in detail below in combination with the drawings:

[0056] First, please refer to Figure 1 A power flight parachute system uses an oil-cooled four-stroke engine 1 and includes an oil tank 2, an engine frame 3, a back flight parachute 4 (the parachute surface is not drawn) and a propeller 5. The bottom surface of the oil-cooled four-stroke engine 1 is provided with the oil tank 2 to send fuel into the oil-cooled four-stroke engine 1. The rear side of the oil-cooled four-stroke engine 1 is connected to the propeller 5, which provides a thrust to the power flight parachute. The oil-cooled four-stroke engine 1 and the oil tank 2 are fixed together in the engine frame 3, and the front side of the engine frame 3 is fixed with the back flight parachute 4 for a person to carry the power flight parachute.

[0057] Please refer to Figure 2 and Figure 3The oil-cooled four-stroke engine 1 comprises an engine body 10, a parachute fixing frame 20, an oil cooler 30, and an oil cooling pipe set 40. The engine body 10 comprises a crankcase 11, a cylinder 12, a cylinder head 13, and an oil passage 14. The oil passage 14 penetrates the side wall of the crankcase 11, the cylinder 12, and the cylinder head 13, and communicates with a camshaft chamber 131 inside the cylinder head 13.

[0058] The specific structure of the engine body 10 of the oil-cooled four-stroke engine 1 is further described below, please continue to refer to Figure 2 and Figure 3 In this embodiment, the crankcase 11 of the engine body 10 further comprises an oil tank 110, a front crankcase 111, a rear crankcase 112, and a crankshaft chamber 113. The oil tank 110 extends downward from the bottom of the crankcase 11. The front and rear crankcases 111 and 112 are combined with each other. The crankshaft chamber 113 is formed between the front and rear crankcases 111 and 112, and communicates with the oil tank 110. As shown in Figure 4A and Figure 4B The front side of the front crankcase 111 forms an oil outlet 141 and an oil inlet 142.

[0059] As shown in Figure 2 , the outside of the front crankcase 111 of the engine body 10 is fixed with a cover plate 15. The cover plate 15 is located between the front crankcase 111 of the engine body 10 and the parachute fixing frame 20. The cover plate 15 comprises a hot oil outlet 151 and a cold oil inlet 152. As shown in Figure 6A , the hot oil outlet 151 communicates with the oil outlet 141 of the front crankcase 111, and the cold oil inlet 152 communicates with the oil inlet 142 of the front crankcase 111.

[0060] As shown in Figure 3 , the outside of the rear crankcase 112 of the engine body 10 extends upward with a propeller shaft fixing column 114. The propeller shaft fixing column 114 is for a propeller shaft 115 to pass through and be fixed. The propeller shaft 115 is connected to a propeller transmission wheel 116 located at the rear side of the rear crankcase 112. The propeller transmission wheel 116 is connected to the propeller 5 as shown in Figure 1 . As shown in Figure 5A and Figure 5BAs shown, the rear side and the front side of the propeller shaft fixing column 114 are integrally formed with a plurality of longitudinal reinforcing arms 114b, and a plurality of transverse reinforcing ribs 114a are further formed between adjacent longitudinal reinforcing arms 114b to reinforce the propeller shaft fixing column 114 and reduce the stress concentration of the propeller shaft fixing column 114 of the rear crankcase 112 caused by the propeller 5 of the power parachute; in the embodiment, the front side and the rear side of the propeller shaft fixing column 114 are formed with three longitudinal reinforcing arms 114b, and the rear side of the propeller shaft fixing column 114 is formed with two transverse reinforcing ribs 114a, but the number is not limited thereto.

[0061] In the embodiment, as shown in Figure 3 The crankcase 11 is provided with a crank assembly 117 inside the crank chamber 113, and the two ends of the crank assembly 117 protrude from the front side of the front crankcase 111 and the rear side of the rear crankcase 112, respectively. The end of the crank assembly 117 protruding from the rear side of the rear crankcase 112 is connected to the propeller transmission wheel 116 of the rear crankcase 112 through a belt 118, so as to transmit power to the propeller transmission wheel 116 through the belt 118, and further transmit power to the propeller 5 of the power parachute as shown in Figure 1 .

[0062] As shown in Figure 2 The cylinder 12 of the engine body 10 is fixed to the outer side of the crankcase 11; in the embodiment, the cylinder 12 is fixed to the right side of the crankcase 11, and is inclinedly fixed to the crankcase 11; as shown in Figure 3 The cylinder 12 comprises a cavity 121 penetrating the cylinder 12 to match a piston 119 arranged on the crank assembly 117.

[0063] As shown in Figure 2 The cylinder cover 13 of the engine body 10 is fixed to the cylinder 12, and as shown in Figure 3 and Figure 6A The cylinder cover 13 comprises a combustion chamber 134 intermittently communicated with the cavity 121 of the cylinder 12 along with the movement of the piston 119; in the embodiment, please refer to Figure 3As shown, a plurality of screwing grooves 16 are formed on the outer side of the crankcase 11, between the cylinder 12 and the cylinder head 13, for the plurality of studs 17 to pass through and be fixed. The camshaft chamber 131 of the cylinder head 13 is for a camshaft 133, two intake valve rocker arms, two intake valves, and two exhaust valves (these components are the existing components of the engine, and thus are not described again) to be arranged therein. Further, the cylinder head 13 comprises a timing inner chain gear chamber 132, which is located behind the camshaft chamber 131 and communicates with the camshaft chamber 131, and further penetrates the rear side of the cylinder 12 and the rear crankcase 112 of the crankcase 11 to communicate with the oil tank 110 and the crank chamber 113. The timing inner chain gear chamber 132 comprises a timing chain 135, which connects the camshaft 133 passing out of the camshaft chamber 131 and into the timing inner chain gear chamber 132 with the crank assembly 117 located at the rear crankcase 112. The timing chain 135 transmits the power of the crank assembly 117 to the camshaft 133, so as to control the opening and closing sequence of the intake valves and the exhaust valves by the valve rocker arms connected with the camshaft 133. In the embodiment, the cylinder head 13 is connected with an exhaust pipe 136 on the side corresponding to the exhaust valves, so as to discharge the exhaust gas generated by the combustion chamber 134 out of the engine body 10.

[0064] The specific structure of the oil passage 14 of the engine body 10 is further described below. Please refer to Figure 5C and Figure 6A In the embodiment, the oil passage 14 comprises a first passage 143, a sub-passage 144, a return passage 145, and a second passage 146. As shown in Figure 6A , the first passage 143 communicates with the oil inlet 142 on the front side of the front crankcase 111, and penetrates the front side of the front crankcase 111, the side wall of the cylinder 12, and the side wall of the cylinder head 13. Please further refer to Figure 4A and Figure 4B As shown, the part of the first passage 143 corresponding to the front crankcase 111 is sequentially formed on the front side of the front crankcase 111, upward, rearward, to the outer side of the cylinder 12, and to one of the screwing grooves 16, so as to communicate with the part of the first passage 143 corresponding to the side wall of the cylinder 12. In the embodiment, as shown in Figure 6A , the part of the first passage 143 corresponding to the cylinder 12 and the cylinder head 13 is directly the screwing groove 16 through which one of the studs 17 passes, and thus does not need to be additionally formed. As shown in Figure 6B , the part of the first passage 143 corresponding to the cylinder head 13 comprises an inner passage 148, and the first passage 143 communicates with the camshaft chamber 131 through the inner passage 148.

[0065] As shown in Figure 4BAs shown, the sub-channel 144 of the aforementioned oil passage is formed inside the front crankcase 111 to communicate with the portion of the front crankcase 111 and the crankshaft chamber 113 corresponding to the first channel 143. In this embodiment, the inner diameter of the sub-channel 144 is smaller than the inner diameter of the first channel 143 of the oil passage 14, but is not limited thereto.

[0066] like Figure 5C As shown, the return channel 145 of the aforementioned oil passage is formed in the rear crankcase 112 to connect the timing inner chain gear chamber 132 and the oil tank 110.

[0067] like Figure 6A As shown, the second channel 146 of the aforementioned oil passage is connected to the oil outlet 141 of the front crankcase 111 and is formed within the front crankcase 111 to communicate with the oil tank 110 of the crankcase 11; in this embodiment, the oil passage 14 further includes an oil pump 147, which is fixed within the front crankcase 111 and connected in series between the second channel 146 and the oil tank 110; and so on. Figure 3 As shown, the oil pump 147 is connected to the crankshaft assembly 117 inside the crankcase 11 by a chain, so that the oil pump 147 uses the power of the crankshaft assembly 117 to transport the oil in the oil tank 110 into the second channel 146 of the oil passage 14.

[0068] like Figure 3 As shown, the parachute mounting bracket 20 of the oil-cooled four-stroke engine 1 is disposed on the front side of the engine body 10 and forms multiple parachute mounting arms 21. A cross arm 22 is formed on one side of the parachute mounting bracket 20 and connects the parachute mounting arms 21 on that side. The parachute mounting arms 21 are used to fix the oil-cooled four-stroke engine 1 to the engine frame 3 of the powered parachute. In this embodiment, the parachute mounting bracket 20 has four parachute mounting arms 21, but it is not limited to this. The cross arm 22 formed on one side of the parachute mounting bracket 20 connects the two parachute mounting arms 21 on that side for fixing the oil cooler 30.

[0069] like Figure 2 As shown, the oil cooler 30 of the aforementioned oil-cooled four-stroke engine 1 is disposed on one side of the parachute mounting frame 20, and includes a cooler body 31, a front fixing plate 32, and a rear fixing plate 33. The cooler body 31 includes a hot oil inlet 311 and a cold oil outlet 312. Figure 2 As shown, in this embodiment, the front fixing plate 32 and the rear fixing plate 33 are fixed together on the cross arm 22 of the parachute fixing frame, and the oil cooler 30 is sandwiched between the front fixing plate 32 and the rear fixing plate 33.

[0070] As shown in Figure 2 , the oil cooling pipe set 40 of the oil-cooled four-stroke engine 1 comprises a hot engine oil pipe 41 and a cold engine oil pipe 42, wherein the hot engine oil pipe 41 and the cold engine oil pipe 42 are connected to the oil passage 14 of the engine body 10, in this embodiment, the hot engine oil pipe 41 is connected to the hot engine oil inlet 311 of the oil cooler 30 and the hot engine oil outlet 151 of the cover plate 15 of the engine body 10, and the cold engine oil pipe 42 is connected to the cold engine oil inlet 312 of the oil cooler 30 and the cold engine oil inlet 152 of the cover plate 15 of the engine body 10, the hot engine oil pipe 41 sends the oil in the oil passage 14 to the oil cooler 30 through the hot engine oil outlet 151 for cooling, and the cooled oil is sent back to the engine body 10 through the cold engine oil pipe 42 and the cold engine oil inlet 152.

[0071] The process of cooling the engine body 10 by the oil cooler 30 and the oil will be further described below, please refer to Figure 2 and Figure 6A , starting from the cold engine oil outlet 312 of the cooler body 31 of the oil cooler 30, as shown in Figure 2 , the cold engine oil leaving the oil cooler 30 flows into the cold engine oil pipe 42 from the cold engine oil outlet 312 of the cooler body 31, and then enters the cover plate 15 through the cold engine oil inlet 152 of the cover plate 15, as shown in Figure 4B , the cold engine oil passes through the oil inlet 142 of the front crankcase 111 and enters the first passage 143 inside the front crankcase 111, as described above, since the inner diameter of the sub-passage 144 is smaller than that of the first passage 143, most of the cold engine oil flows through the first passage 143 to the screw groove 16 of the cylinder 12, i.e. the part of the first passage 143 corresponding to the cylinder 12, and the rest enters the sub-passage 144 and flows to the crank chamber 113 of the crankcase 11.

[0072] Please refer to Figure 6A and 6B , the cold engine oil flows to the screw groove 16 of the cylinder 12, i.e. the part of the first passage 143 corresponding to the cylinder 12 and the cylinder head 13, after passing through the front crankcase 111, to absorb the excess heat generated by the combustion chamber 134 of the cylinder head 13, thereby cooling the engine body 10 and forming hot engine oil, which then enters the camshaft chamber 131 through the inner passage 148; after passing through the camshaft chamber 131 of the cylinder head 13, the hot engine oil enters the timing inner chain gear chamber 132, and then flows to the rear crankcase 112 under the action of gravity, as shown inFigure 5C As shown, the hot engine oil merges with the engine oil flowing out of the crankshaft chamber 113 at a bottom of the timing inner chain gear chamber 132 inside the rear crankcase 112, and then flows back to the engine oil tank 110 of the crankcase 11 through the return channel 145.

[0073] like Figure 6A As shown, the hot engine oil collects in the oil tank 110 of the crankcase 11, is pressurized by the oil pump 147 located between the oil tank 110 and the second channel 146, and then exits the front crankcase 111 from the oil outlet 141. The hot engine oil then sequentially passes through the hot engine oil outlet 151 and the hot engine oil pipe 41, and enters the cooler body 31 from the hot engine oil inlet 311 of the oil cooler 30. Finally, the hot engine oil is cooled by the cooler body 31 to form the cold engine oil, which then enters the cold engine oil pipe 42 through the cold engine oil outlet 312 for recirculation. In this embodiment, since the oil-cooled four-stroke engine 1 utilizes the oil cooler 30 to simultaneously cool and lubricate the engine oil, the maximum oil temperature of the hot engine oil can be reduced to below 100 degrees Celsius. Figure 2 The total weight of the oil-cooled four-stroke engine shown is as light as 17 kg, compared to Figure 7 The total weight of the water-cooled four-stroke engine 60, equipped with the water tank 61, the cold water pipe 63, the hot water pipe 64, and cooling water, is 23 to 25 kg. The total weight of the oil-cooled four-stroke engine 1 of the present invention can be reduced by about 6-8 kg. Taking the specifications of this embodiment with a cylinder bore of 73 mm and a crankshaft stroke of 67.9 mm as an example, the displacement of the oil-cooled four-stroke engine 1 of the present invention is about 284.17 cc (73*73*3.1415*67.9 / 1000), therefore, compared to... Figure 7 The 250cc water-cooled four-stroke engine shown has an additional 34.17cc displacement.

[0074] As known from the above description, the oil-cooled four-stroke engine of the present application forms the oil passage inside the engine body, and sets and fixes the oil cooler on one side of the parachute fixing frame, and then connects the oil passage and the oil cooler by using an oil cooling pipe set, the hot oil pipe of which guides the hot oil inside the engine body from the oil outlet of the oil passage to the oil cooler to cool the hot oil and form the cold oil, and then uses the cold oil pipe of the oil cooling pipe set to guide the cold oil back to the oil inlet of the oil passage and into the engine body for repeated circulation, so that the oil can play the cooling and lubricating effects at the same time; in addition, the present application integrally forms a plurality of transverse reinforcing ribs and a plurality of longitudinal reinforcing arms on the front side and the rear side of the propeller shaft fixing column of the rear crankcase of the engine body to reinforce the propeller shaft fixing column and reduce the stress concentration of the rear crankcase caused by the use of the propeller; thus, the oil-cooled four-stroke engine of the present application for power parachute does not need to be externally hung with a cooling water tank, but can use the oil cooler to cool the oil and indirectly cool the engine body, which can effectively reduce the weight of the oil-cooled four-stroke engine, the weight burden of the user and the consumption of the flying fuel.

[0075] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims attached to the present application.

Claims

1. An oil-cooled four-stroke engine for a powered paraglider, characterized in that, Comprising: an engine body comprising at least a crankcase, a cylinder, a cylinder head, and an oil passage, wherein the oil passage is through a side wall of the crankcase, the cylinder, and the cylinder head, and is in communication with a camshaft chamber of the cylinder head; wherein a rear side of the oil-cooled four-stroke engine is for connecting a propeller; a parachute mount disposed at a front side of the engine body; an oil cooler disposed at a side of the parachute mount so as to be located at the front side of the engine body; and an oil cooling pipe set in communication with the oil cooler and the oil passage of the engine body; the crankcase comprises: an oil tank extending downward from a bottom of the crankcase; a front crankcase having a front side forming an oil inlet and an oil outlet; a rear crankcase combined with the front crankcase; and a crank chamber formed between the front crankcase and the rear crankcase and in communication with the oil tank; and the cylinder head comprises a timing inner chain gear chamber located behind and in communication with the camshaft chamber, and the timing inner chain gear chamber is through a rear side of the cylinder and the rear crankcase of the crankcase, and is in communication with the oil tank of the crankcase; the oil passage comprises: a first passage in communication with the oil inlet of the front crankcase and through the front crankcase, the cylinder, and the side wall of the cylinder head, and in communication with the camshaft chamber of the cylinder head; a sub-passage formed in the front crankcase to communicate the first passage and the crank chamber; a return passage formed in the rear crankcase to communicate the timing inner chain gear chamber and the oil tank; and a second passage formed in the front crankcase to communicate with the oil tank.

2. The oil-cooled four-stroke engine for a powered paraglider according to claim 1, characterized in that, wherein: an outer side of the crankcase sequentially fixes the cylinder and the cylinder head with a plurality of studs, wherein the outer side of the crankcase corresponds to the side wall of the cylinder and the cylinder head to form a screw groove for each stud; a portion of the first passage corresponding to the side wall of the cylinder and the cylinder head is one of the screw grooves; and a portion of the first passage of the oil passage corresponding to the cylinder head comprises an inner passage, and the first passage is in communication with the camshaft chamber through the inner passage. further comprising an oil pump fixed in the front crankcase and connected between the second passage and the oil tank.

3. An oil-cooled four-stroke engine for a powered paraglider according to claim 1 or 2, characterized in that, wherein:

4. The oil-cooled four-stroke engine for a powered paraglider according to claim 3, characterized in that, the parachute mount comprises: a plurality of parachute fixing arms; and a cross arm connecting two of the parachute fixing arms; and the oil cooler comprises: a front fixing plate fixed to the cross arm of the parachute mount; a rear fixing plate fixed to the cross arm of the parachute mount; and a cooler body sandwiched between the front fixing plate and the rear fixing plate. wherein:

5. The oil-cooled four-stroke engine for a powered paraglider according to claim 4, characterized in that, the oil cooling pipe set comprises: a hot oil pipe connected to the hot oil inlet of the cooler body and the hot oil outlet of the cover plate; and a cold oil pipe connected to the cold oil outlet of the cooler body and the cold oil inlet of the cover plate; an outer side of the front crankcase of the engine body is fixed with a cover plate located between the front crankcase of the engine body and the parachute mount, which comprises: a cold oil inlet connected to the cold oil pipe of the oil cooling pipe set and in communication with the oil inlet of the front crankcase; and ​ A hot engine oil outlet connected to the hot engine oil pipe of the oil cooling pipe assembly and in communication with the engine oil outlet of the front crankcase.

6. The oil-cooled four-stroke engine for a powered paraglider according to claim 1, wherein The inner diameter of the sub-passage of the engine oil passage is smaller than the inner diameter of the first passage of the engine oil passage.

7. The oil-cooled four-stroke engine for a powered parachute as in claim 1 wherein, The outer side of the rear crankcase extends upwardly with a propeller shaft fixing column, which comprises: A plurality of longitudinal reinforcing arms integrally formed on the front side and the rear side of the propeller shaft fixing column; and A plurality of transverse reinforcing ribs respectively formed between adjacent longitudinal reinforcing arms on the rear side of the propeller shaft fixing column.

8. The oil-cooled four-stroke engine for a powered paraglider according to claim 7, characterized in that, The propeller shaft fixing column of the rear crankcase is provided for a propeller shaft to pass through and be fixed, and the propeller shaft is connected to a propeller transmission wheel.

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