Patent Application
20250206432
This application claims the benefit of priority to Japanese Patent Application No. 2023-219171 filed on Dec. 26, 2023. The entire contents of this application are hereby incorporated herein by reference.
The technologies disclosed herein relate to boat propulsion devices, boats, and movable bodies.
A conventional outboard motor, which is an example of a boat propulsion device, is equipped with a thermostat that is installed in a cooling water flow path to increase or decrease the flow rate of water flowing around the engine. In a conventional outboard motor, the thermostat is installed downstream of the portion of the cooling water flow path that passes around the engine (see, e.g., JP 2019-074011 A).
The above-mentioned boat propulsion device has the problem that the engine warm-up speed is low because the volume of the cooling water near the engine does not decrease even when the engine temperature is low enough that cooling is not required.
Example embodiments of the present invention disclose technologies that are able to solve the above-described problem.
The technologies disclosed herein can be implemented, e.g., in the following example embodiments.
According to an example embodiment of the present invention, a boat propulsion device includes an engine, an oil pan to store oil to be supplied to the engine, a case to accommodate at least a portion of the oil pan, and a pump to pump cooling water to a cooling water flow path in the boat propulsion device. The cooling water flow path includes a first flow path extending between the oil pan, the case, and the engine, and a second flow path branching from the first flow path at a location between the oil pan and the case and not extending to the engine. The boat propulsion device further includes a flow rate regulator to change at least one of a flow rate of the cooling water flowing into the first flow path and a flow rate of the cooling water flowing out of the first flow path.
According to the above-described boat propulsion device, when the engine temperature is low, a volume of the cooling water near the engine is reduced thus increasing the engine warm-up speed.
The technologies disclosed herein can be implemented in a variety of example embodiments, including, e.g., boat propulsion devices, boats including boat propulsion devices and hulls, and a movable bodies.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.
The boat 10 includes a hull 200 and an outboard motor 100. In an example embodiment, the boat 10 includes only one outboard motor 100, but the boat 10 may include a plurality of outboard motors 100.
The hull 200 is a portion of the boat 10 for occupants to ride. The hull 200 includes a hull main body 202 including a living space 204, a pilot seat 240 in the living space 204, and an operating device 250 near the pilot seat 240. The operating device 250 steers the boat and includes, e.g., a steering wheel 252, a shift/throttle lever 254, a joystick 255, a monitor 256, and an input device 258. The hull 200 includes a partition wall 220 to partition the rear end of the living space 204 and a transom 210 positioned at the rear end of the hull 200. In the front-rear direction, a space 206 is provided between the transom 210 and the partition wall 220.
The outboard motor 100 generates thrust to propel the boat 10. The outboard motor 100 is attached to the transom 210 at a rear portion of the hull 200. The outboard motor 100 includes an outboard motor main body 110 and a suspension device 150.
The outboard motor main body 110 includes a cowl 112, a casing 116, an engine 120, a transmission mechanism 130, a propeller 111, a pump shaft 134, a water pump 140, and an oil pan 500.
The cowl 112 is a housing located on top of the outboard motor main body 110. The cowl 112 includes an upper cowl 113 defining an upper portion of the cowl 112 and a lower cowl 114 defining a lower portion of the cowl 112. The upper cowl 113 is detachably attached to the lower cowl 114.
The casing 116 is a housing located below the cowl 112 and provided in the lower portion of the outboard motor main body 110. The casing 116 includes an upper case 117 defining an upper portion of the casing 116 and a lower case 118 defining a lower portion of the casing 116. The upper case 117 accommodates at least a portion of the oil pan 500. The upper case 117 is an example of the case.
The engine 120 is a prime mover to generate power. The engine 120 includes, e.g., an internal combustion engine including a combustion chamber where fuel is burned (not shown). The engine 120 is located in a relatively upper portion of the outboard motor main body 110 and is accommodated in the cowl 112. The engine 120 includes a crank shaft 124 to convert the reciprocating motion of the piston, not shown, into rotational motion. The crank shaft 124 is arranged in an attitude in which its rotation axis Ac extends in the upper-lower direction.
The transmission mechanism 130 transmits the driving force of the engine 120 to the propeller 111. The transmission mechanism 130 includes an output shaft 132, a shift mechanism 300, a drive shaft 133, and a propeller shaft 137.
The output shaft 132 is a rod-shaped member extending in the upper-lower direction. The upper end of the output shaft 132 is mechanically connected to the lower end of the crank shaft 124 in the engine 120 and extends downward from a connection portion with the engine 120. The output shaft 132 rotates with the crank shaft 124 under the driving force of the engine 120.
The shift mechanism 300 is connected to the lower portion of the output shaft 132. The shift mechanism 300 transmits the driving force of the output shaft 132 to the drive shaft 133 and the pump shaft 134. By switching the rotating direction of the drive shaft 133, the shift mechanism 300 changes the rotating direction of the propeller shaft 137 and the propeller 111, thus switching the boat 10 between the forward and backward movement states.
The drive shaft 133 is a rod-shaped member that transmits power to the propeller shaft 137. The lower end of the drive shaft 133 includes a gear 135. The drive shaft 133 is mechanically connected to the propeller shaft 137 by meshing the gear 135 of the drive shaft 133 with the gear 138 of the propeller shaft 137, as described below. Rotation of the drive shaft 133 is transmitted to the propeller shaft 137 via the gear 135 of the drive shaft 133 and the gear 138 of the propeller shaft 137.
The propeller shaft 137 is a rod-shaped member and extends in the front-rear direction at a height relatively lower than the outboard motor main body 110. The propeller shaft 137 rotates with the propeller 111. The front end of the propeller shaft 137 is accommodated in the lower case 118, and the rear end of the propeller shaft 137 protrudes rearward from the lower case 118. The front end of the propeller shaft 137 includes a gear 138.
The propeller 111 is a rotor with a plurality of blades and is attached to the rear end of the propeller shaft 137. The propeller 111 rotates along with the rotation of the propeller shaft 137 about the rotation axis Ap. The propeller 111 generates thrust by rotating.
The pump shaft 134 extends in an upper-lower direction. The pump shaft 134 is driven by the driving power of the engine 120 transmitted by the output shaft 132 and the shift mechanism 300 to transmit power to the water pump 140.
The water pump 140 pumps cooling water to the cooling water flow path 400 in the outboard motor 100, which will be described below. The water pump 140 pumps water from outside the outboard motor 100. The water pump 140 is driven by the drive power of the engine 120 transmitted by the pump shaft 134. The water pump 140 is an example of the pump.
The oil pan 500 stores oil to be supplied to the engine 120. The oil has, e.g., a lubricating and cleaning function for the engine 120. The oil stored in the oil pan 500 is pumped by an oil pump (not shown) and circulates in the engine 120. The oil pan 500 is located higher than the water pump 140 and lower than the engine 120.
The suspension device 150 attaches the outboard motor main body 110 to the hull 200. The suspension device 150 includes a pair of left and right clamp brackets 152, a tilt shaft 154, and a swivel bracket 156.
The pair of left and right clamp brackets 152 are disposed behind the hull 200 in a state separated from each other in the left-right direction and are fixed to the transom 210 of the hull 200 by using, e.g., bolts. Each clamp bracket 152 has a cylindrical supporting portion 153 provided with a through-hole extending in the left-right direction.
The tilt shaft 154 is a rod-shaped member and is rotatably supported within the through-hole in the supporting portion 153 of the clamp bracket 152. The tilt axis At, which is the centerline of the tilt shaft 154, defines the horizontal (left-right) axis in the tilting operation of the outboard motor 100.
The swivel bracket 156 is sandwiched between the pair of clamp brackets 152 and is supported by the supporting portion 153 of the clamp brackets 152 via the tilt shaft 154 so as to be rotatable about the tilt axis At. The swivel bracket 156 is driven to rotate about the tilt axis At with respect to the clamp bracket 152 by a tilt device (not shown) that includes an actuator, such as a hydraulic cylinder, for example.
When the swivel bracket 156 rotates about the tilt axis At with respect to the clamp bracket 152, the outboard motor main body 110 supported by the swivel bracket 156 also rotates about the tilt axis At. This achieves the tilting operation of rotating the outboard motor main body 110 in the upper-lower direction with respect to the hull 200. By this tilting operation, the outboard motor 100 can change the angle of the outboard motor main body 110 about the tilt axis At in the range from the tilt-down state in which the propeller 111 is located under the water (the state in which the outboard motor 100 is in the reference attitude) to the tilt-up state in which the propeller 111 is located above the water surface. Trimming operation to adjust the attitude of the boat 10 during travel can also be performed by adjusting the angle about the tilt axis At of the outboard motor main body 110.
The cooling water flow path 400 includes a first flow path 410 and a second flow path 420 (see
The first flow path 410 is a flow path of cooling water primarily for cooling the engine 120. The first flow path 410 is configured such that the cooling water pumped by the water pump 140 passes between the oil pan 500 and the upper case 117, then around the engine 120, and then again between the oil pan 500 and the upper case 117. The first flow path 410 is configured such that the cooling water contacts the oil pan 500. Thus, the cooling water passing through the first flow path 410 passes around the oil pan 500, allowing heat transfer with the oil pan 500. Therefore, the cooling water passing through the first flow path 410 can cool not only the engine 120 but also the oil stored in the oil pan 500.
The inlet flow path 411 of the first flow path 410 extends from the water pump 140 and into the area around the combustion chamber in the engine 120. The inlet flow path 411 is configured such that the cooling water flows upward from the water pump 140. More specifically, in the inlet flow path 411, the cooling water is pumped from the water pump 140, flows around the oil pan 500, and flows toward the periphery of the combustion chamber of the engine 120, which is located above the cross-section shown in
The outlet flow path of the first flow path 410 extends from the periphery of the combustion chamber in the engine 120 to the outside of the outboard motor 100. The outlet flow path 412 is configured such that the cooling water flows downward from the periphery of the combustion chamber in the engine 120. More specifically, in the outlet flow path 412, the cooling water is discharged from the periphery of the combustion chamber in the engine 120, which is located above the cross-section shown in
As shown in
The outboard motor 100 further includes a valve 430 that changes at least one of the flow rate of the cooling water flowing into the first flow path 410 and the flow rate of the cooling water flowing out of the first flow path 410. The valve 430 is located outside the upper case 117 and is located in the middle of the second flow path 420. The outboard motor 100 adjusts the flow rate of the cooling water flowing into the first flow path 410 and the flow rate of the cooling water flowing into the second flow path 420 by opening and closing the valve 430. Specifically, the outboard motor 100 decreases the flow rate of cooling water flowing into the second flow path 420 and increases the flow rate of cooling water flowing into the first flow path 410 by closing the valve 430. Conversely, the outboard motor 100 increases the flow rate of cooling water flowing into the second flow path 420 and decreases the flow rate of cooling water flowing into the first flow path 410 by opening the valve 430. This allows the flow rate of the cooling water flowing into the first flow path 410 to be changed without changing the rotational speed of the engine 120. The valve 430 is an example of the flow rate regulator.
The valve 430 can be adjusted to any valve opening from 0% to 100%. This allows the cooling water pumped by the water pump 140 to flow into the first flow path 410 at any flow rate from 0% to 100%. Similarly, the cooling water pumped by the water pump 140 can be allowed to flow into the second flow path 420 at any flow rate from 0% to 100%.
The outboard motor 100 further includes a controller 80. The controller 80 may include, e.g., a CPU, a multi-core CPU, and a programmable device (field programmable gate array (FPGA), programmable logic device (PLD), and the like). The controller 80 is electrically connected to each of the first temperature sensor 441, the second temperature sensor 442, the third temperature sensor 443, the fourth temperature sensor 444, the valve 430, and the engine 120.
The above “predetermined values” may be different from each other for the first temperature sensor 441, the second temperature sensor 442, the third temperature sensor 443, and the fourth temperature sensor 444. With respect to the above “predetermined values”, the value that serves as the basis to switch the flow rate of the cooling water flowing into the first flow path 410 and the value that serves as the basis to switch the rotation speed of the engine 120 may be different from each other.
Next, the performance evaluation of the outboard motor 100 is described. The engine warm-up speeds were measured for outboard motors with different cooling water flow path configurations. A temperature sensor was placed near the combustion chamber of the engine, and the temperature near the combustion chamber of the engine was measured for a certain time after the engine was started.
As shown in
The valve 430a in the outboard motor 100a is a three-way valve and is located inside the upper case 117. The second flow path 420a extends downward in the outboard motor 100a from the connection position 422 with the valve 430a. The outlet of the second flow path 420a is located at a lower portion of the outboard motor 100a, which is located below the cross-section shown in
The valve 430b in the outboard motor 100b is a three-way valve and is located inside the upper case 117. The second flow path 420b extends upward in the outboard motor 100b from the connection position 422 with the valve 430b. The second flow path 420b is configured such that the cooling water passes around the ignition plug in the combustion chamber in the engine 120, which is located above the cross-section shown in
The techniques disclosed herein are not limited to the above-described example embodiments and may be modified in various ways without departing from the gist of the present invention, including the following modifications.
The configuration of the boat 10 and the outboard motor 100 of the example embodiments are only examples and may be variously modified. For example, in the above example embodiments, the outboard motor 100 is shown as an example of the boat propulsion device, but it can be an inboard motor or a jet propulsion system, for example.
In the above example embodiments, the outboard motor 100 is provided with only the engine 120 as a drive source, but the boat propulsion device may be a hybrid type equipped with a motor in addition to the engine.
In the above example embodiments, the outboard motor 100 is provided with the first temperature sensor 441, the second temperature sensor 442, the third temperature sensor 443, and the fourth temperature sensor 444, but the outboard motor may not be provided with at least one of these temperature sensors or may have another temperature sensor.
In the above example embodiments, the outboard motor 100 is provided with the controller 80, but the outboard motor need not necessarily be provided with a controller.
In the above example embodiments, the first flow path 410 and the second flow path 420 branch at a height lower than the lower end of the oil pan 500, but the branching location is not necessarily limited thereto.
In the above example embodiments, the valves 430, 430a, and 430b are provided as the flow path regulator, but the flow path regulator does not necessarily need to be a valve.
In the above example embodiments, the valve 430 is adjusted to any valve opening from 0% to 100%, but the range is not necessarily limited thereto.
Although the above example embodiments describe the outboard motor 100 and the boat 10 provided with the outboard motor 100, the technologies disclosed herein are equally applicable to movable bodies such as, e.g., vehicles and motorcycles.
While example embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-219171 | Dec 2023 | JP | national |
