Patent Grant
9010298
The present application claims priority from Japanese Patent Application No. 2010-094583 filed on Apr. 16, 2010, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a rollover detection device for a general-purpose engine for detecting a rollover of a driving unit such as a rammer that is driven by a general-purpose engine.
2. Description of the Related Art
A rolling compaction machine for use in compacting a paved surface or ground surface is called a “rammer.” As described in Japanese Utility Model Registration No. 3122696, a general-purpose engine is used for driving a rolling compaction plate, or a rammer member, wherein the rammer member serves as a member to be driven by the general-purpose engine. The general-purpose engine mounted in a driving unit such as a rammer has a crankcase in which a crankshaft is installed rotatably, and a cylinder in which a piston connected to the crankshaft by a piston rod is incorporated so as to be able to reciprocate axially. A bottom part of the crankcase is provided with an oil pan to store lubricating oil. The lubricating oil is supplied to a lubrication section, which is a sliding section such as a bearing that supports the crankshaft rotatably. The crankcase is provided with an oil pump for supplying the lubricating oil to the sliding section, and the oil pump is driven by the crankshaft.
As described in Japanese Unexamined Patent Application Publication Nos. 1992-241713 and 1997-49414, a strainer is incorporated in a tip end of a lubricating oil feed pipe for guiding the lubricating oil to the oil pump. The lubricating oil within the oil pan is drawn through the strainer, functioning as a drawing port, into the lubricating oil feed pipe and then supplied to the sliding section.
Japanese Patent No. 2713765, on the other hand, describes an engine stop device that is provided with a detection switch for detecting the amount of lubricating oil stored in an oil pan of a general-purpose engine, and stops the engine when the amount of lubricating oil drops to a certain level or lower.
The driving unit such as a rammer is tilted when used, depending on the conditions in which the driving unit is used. When the driving unit is tilted, naturally the general-purpose engine mounted in such a driving unit is also tilted. Even when the driving unit is tilted under normal use, the lubricating oil within the oil pan can be supplied to the oil pump and hence to the sliding section. However, if the driving unit rolls over, even when the engine is driven while having a predetermined amount of lubricating oil stored in the oil pan, the lubricating oil cannot be suctioned into the lubricating oil feed pipe.
With regard to rollover directions in which the driving unit such as a rammer can roll over, there are two, front and rear, rollover directions where the front surface side or the rear surface side of the engine is tilted downward, and there are two, left and right, rollover directions where the left-side surface or the right-side surface of the engine is tilted downward. The driving unit sometimes rolls over in multiple directions, such as to the front and to the right. When the driving unit rolls over in such a manner, the lubricating oil cannot be guided to the oil pump or supplied to the sliding section. Subsequently, the lubricating oil enters the inside of the piston or other parts that require no lubrication. In this case, the engine needs to be stopped. Examples of the conditions where the driving unit rolls over include not only when the front surface side or the rear surface side of the engine is tilted completely downward, but also when the driving unit tilts to the extent that the engine needs to be stopped.
Although detection of a rollover of the engine was attempted by attaching a rollover sensor to the driving unit, it is inevitable for the rollover sensor to erroneously detect a rollover of the driving unit such as a rammer, which vibrates. Thus, a rollover could not be detected accurately.
Because the lubricating oil within the oil pan is not guided to the lubricating oil feed pipe when the driving unit rolls over, a pressure sensor is provided at a discharge port of the oil pump to detect that the lubricating oil is not discharged from the oil pump and thereby detect a rollover of the driving unit.
However, it is necessary to take into consideration that the driving unit rolls over in all of front-rear and left-right directions described above. In a general-purpose engine in which the oil pump is incorporated in an end wall part of the crankcase and the strainer is incorporated within the end wall part, the pressure sensor cannot detect a rollover in a certain direction. In other words, when the driving unit rolls over in such a direction where an opening part of the strainer is tilted upward, the lubricating oil is stopped from being guided from the opening part of the strainer to the lubricating oil feed pipe, and consequently the pressure of the lubricating oil in the discharge port of the oil pump can be detected to determine the rollover of the driving unit. On the other hand, when the driving unit rolls over in such a direction where the opening of the strainer is tilted downward, the lubricating oil is guided from the opening part to the lubricating oil feed pipe, and, as a result, the rollover of the driving unit cannot be detected.
An object of the present invention is to be able to detect a rollover of a driving unit in any direction when the driving unit is driven by a general-purpose engine.
A rollover detection device for a general-purpose engine according to the present invention is a rollover detection device for a general-purpose engine for detecting a rollover of a driving unit that has a member to be driven by an engine, the rollover detection device including: an engine main body that has a cylinder in which a piston is installed so as to be able to reciprocate, and a crankcase in which a crankshaft connected to the piston by a connecting rod is installed rotatably; an oil pan provided in a bottom part of the crankcase and storing lubricating oil; an oil pump that is driven to rotate by the crankshaft; a lubricating oil intake part, a suction port of which is provided at a position away from an end wall surface and side wall surface of the oil pan, and which guides the lubricating oil to an intake port of the oil pump; a lubricating oil discharge part that guides the lubricating oil to a nozzle that supplies the lubricating oil, which is discharged from a discharge port of the oil pump, to a lubrication section within the engine main body; discharge detecting means for detecting whether or not the lubricating oil is discharged from the discharge port of the oil pump; and engine stop control means for stopping the engine when the lubricating oil is not discharged into the lubricating oil discharge part.
The rollover detection device for a general-purpose engine according to the present invention is characterized in that the engine stop control means stops the engine when a state in which the lubricating oil is not discharged into the lubricating oil discharge part continues for a stop determination time or longer. The rollover detection device for a general-purpose engine according to the present invention is characterized in that the suction port of the lubricating oil intake part is opened at a central part of the oil pan in both a direction along the crankshaft and a direction perpendicular to the crankshaft. The rollover detection device for a general-purpose engine according to the present invention is characterized in that the oil pump is installed in an end wall part of the crankcase in which the crankshaft is supported rotatably, that an intake-side communication hole is formed within the end wall part, that a lubricating oil suction pipe formed with the suction port is attached to an opening part of the intake-side communication hole that is opened to the oil pan, and that the lubricating oil intake part is formed by the intake-side communication hole and the lubricating oil suction pipe. The rollover detection device for a general-purpose engine according to the present invention is characterized in that a discharge-side communication hole for allowing a communication between the discharge port and the nozzle is formed in the end wall part, and that the lubricating oil discharge part is formed by the discharge-side communication hole.
The rollover detection device for a general-purpose engine according to the present invention is characterized in that the discharge detecting means is a pressure sensor that detects a pressure of the lubricating oil discharged to the lubricating oil discharge part, and outputs a detection signal to the engine stop control means when a discharge pressure reaches a lubrication pressure. The rollover detection device for a general-purpose engine according to the present invention is characterized in that the discharge detecting means is disposed within the lubricating oil discharge part. The rollover detection device for a general-purpose engine according to the present invention is characterized in that within the lubricating oil intake part there is provided a filtering member for filtering the lubricating oil that is supplied from within the oil pan to the nozzle. The rollover detection device for a general-purpose engine according to the present invention is characterized in that the filtering member is attached to a sealing plug that is detachably installed in the lubricating oil intake part, and that the lubricating oil stored in the oil pan is discharged through the lubricating oil intake part by removing the sealing plug from the crankcase along with the filtering member.
According to the present invention, because the lubricating oil within the oil pan is stopped from being discharged toward the discharge port of the oil pump when the general-purpose engine rolls over, detecting whether or not the lubricating oil is discharged to the discharge port allows detection of the rollover of the general-purpose engine. A rollover of the general-purpose engine in any direction, whether a front-rear direction in which the crankshaft tilts or a left-right direction in which the crankshaft rotates, can be reliably detected.
Determining whether or not the general-purpose engine rolls over is performed after the stop determination time elapses since the lubricating oil is stopped from being discharged to the discharge port. In this manner, the rollover is determined after the engine is started and consequently the oil pump driven by the engine enters a steady state thereof. As a result, a rollover determination can be prevented from being erroneously performed when the engine is started while the rollover detection device is in a normal upright state.
Embodiments of the present invention are now described hereinafter in detail with reference to the drawings. A rammer 10, a tamping rammer functioning as a rolling compaction machine driven by a general-purpose engine, has a rammer member 11 as a member to be driven by the general-purpose engine, as shown in
As shown in
A general-purpose engine 17 is installed on the rear surface side of the rammer crankcase 13, which is the operation surface of the rammer crankcase 13. This general-purpose engine 17 is a four-cycle single-cylinder engine with a cylinder 18, as shown in
As shown in
A cylinder head 24, fixed to the cylinder 18, has formed therein an inlet port, not shown, for supplying an air-fuel mixture to a combustion chamber 24a, and an outlet port, not shown, for discharging combustion gas. As shown in
The cylinder head 24 is provided with an inlet valve, not shown, for opening/closing the inlet port and an outlet valve, also not shown, for opening/closing the outlet port. The inlet valve and the outlet valve are each driven to open/close by a dynamic valve mechanism 28. The dynamic valve mechanism 28 is covered by a locker cover 29 attached to the cylinder 18 and has a camshaft 30 that is installed in the cylinder head 24 in parallel with the crankshaft 21. One end part of a locker arm 32 for the inlet valve and one end part of a locker arm 32 for the outlet valve that are installed swingably in the cylinder head 24 abut on a dynamic valve cam 31 provided in the camshaft 30. The other end of the locker arm 32 for the inlet valve is connected to the inlet valve, and the locker arm 32 for the outlet valve is connected to the outlet valve. A timing belt 35 is stretched between a sprocket 33 attached to the cylinder head 24 and a sprocket 34 attached to the crankshaft 21. The camshaft 30 is driven to rotate by the crankshaft 21. The timing belt 35 extends between the sprockets 33 and 34 through a through-hole 18a formed in the cylinder 18.
As shown in
As shown in
As shown in
A bottom part of the crankcase 20 is provided with an oil pan 51 for storing lubricating oil L. As shown in
An oil pump 52 is installed in the end wall part 20c of the crankcase 20 in order to supply the lubricating oil L to the connection part between the crankshaft 21 and the connecting rod 22, as well as lubrication sections or sliding sections such as a bearing for supporting the crankshaft 21 in the crankcase 20. The oil pump 52 is disposed between the end wall part 20c and a cover 53 attached thereto. The oil pump 52 is driven by the crankshaft 21 to discharge the lubricating oil L, supplied to an intake port 54 of the oil pump 52, from a discharge port 55.
An intake-side communication hole 56 is formed in the end wall part 20c in order to guide the lubricating oil L of the oil pan 51 to the intake port 54. A lower end part of this intake-side communication hole 56, which is a radial outer portion located with respect to the crankshaft 21, configures a large diameter part 56a larger than an upper end part of the intake-side communication hole 56. This large diameter part 56a, opened to the outside of the end wall part 20c, opens downward when the rammer 10 is set upright. A filter 57 serving as a filtering member is detachably installed in the large diameter part 56a that is opened to the outside. This filter 57 is attached to a sealing plug 58 that is screwed to the end wall part 20c. When the sealing plug 58 is removed from the end wall part 20c, the filter 57 is also removed along with the sealing plug 58, whereby the lubricating oil L within the oil pan 51 can be discharged to the outside. In this manner, by attaching the filter 57 to the sealing plug 58 which is detachably installed in the intake-side communication hole 56, the filter 57 can be attached or removed using the sealing plug 58. Additionally, by removing the sealing plug 58, the intake-side communication hole 56 can be used as a channel for discharging the lubricating oil.
As shown in
As shown in
A discharge-side communication hole 63 that is communicated with the discharge port 55 of the oil pump 52 is formed in the end wall part 20c, and a nozzle 64 in which an oil passage 64a communicated with the discharge-side communication hole 63 is formed is attached to the end wall part 20c. The discharge-side communication hole 63 forms a lubricating oil discharge part 65 for guiding the lubricating oil L, discharged from the discharge port 55, to the nozzle 64. Forming the discharge-side communication hole 63 in the end wall part 20c using the end wall part 20c to configure a part of the lubricating oil discharge part 65 eliminates the need to attach a pipe member for forming the lubricating oil discharge part 65 in the end wall part 20c, so that the lubricating oil discharge part 65 can be formed in a limited space.
The lubricating oil L that is pressurized to lubrication pressure by the oil pump 52 is injected from a tip end part of the nozzle 64 to the sliding sections, or the lubrication sections. As shown in
An upper end part of the discharge-side communication hole 63, which is a radial outer portion located with respect to the crankshaft 21, configures a large diameter part 63a larger than a lower end part of the discharge-side communication hole 63. The large diameter part 63a is opened to the outside of the end wall part 20c. A pressure sensor 66 that serves as the discharge detecting means for detecting whether or not the lubricating oil is discharged from the discharge port 55 of the oil pump 52 is attached to the large diameter part 63a opened to the outside. This pressure sensor 66 outputs a detection signal when the pressure of the lubricating oil L discharged from the discharge port 55 of the oil pump 52 reaches the lubrication pressure, but does not output any signals when the pressure does not reach the lubrication pressure. Various types of pressure sensors, such as a semiconductor pressure sensor or piezoelectric pressure sensor, can be used as the pressure sensor 66. Whether the rammer 10 is rolled over or not is detected based on the signal output from the pressure sensor 66.
In
When the oil level comes to the level shown by a reference numeral L1 in
In
As shown in
When the lubricating oil L is no longer discharged from the discharge port 55, the pressure sensor 66 stops outputting the pressure detection signals. As a result, the rollover of the general-purpose engine 17, or the rollover of the rammer 10, can be determined based on the pressure detection signals.
In the case of obtaining a configuration for detecting a rollover of the general-purpose engine 17 when the engine main body 17a rolls over to the positions shown in
Although the suction port 62 is provided at the bottom part of the oil pan 51, the suction port 62 may be provided at a position higher than the illustrated positions, in the case of detecting a reduction in the remaining lubricating oil by means of the pressure sensor 66 when the oil level decreases to below a predetermined position as a result of a reduction in the amount of the lubricating oil L.
When the rammer 10 rolls over after the engine is driven while the rammer 10 is not rolled over, the engine is stopped after the stop determination time elapses since the rollover. In this case, the engine may be immediately stopped even before the stop determination time elapses.
As described above, based on whether the pressure of the lubricating oil discharged from the oil pump 52 is at the lubrication pressure or not, a rollover of the general-purpose engine or the driving unit such as the rammer 10 is detected when the general-purpose engine or the driving unit rolls over in any of the four directions, i.e., to the front, rear, left and right. Consequently, whether the driving unit rolls over or not can be detected reliably without using the rollover sensor.
When the operator uses the above-mentioned rammer 10 to compact a paved surface or ground surface, the operator pulls out the operating knob 48 to start the engine while keeping the rammer 10 upright, as shown in
When it is determined that the lubricating oil L is discharged from the oil pump 52 to the lubricating oil discharge part 65, the rammer 10 is driven without having the engine stopped. However, when the engine is started while the rammer 10 is rolled over, this means that the engine is started when the lubricating oil L does not flow into the lubricating oil intake part 61. Therefore, the lubricating oil, the pressure of which is increased to the lubricating oil, is stopped from being discharged to the discharge port 55 after a lapse of the stop determination time. As a result, the drive of the engine is stopped. On the other hand, when the rammer 10 rolls over while the rammer 10 with the general-purpose engine 17 driven is used for compacting a paved surface or ground surface, the lubricating oil L is no longer supplied continuously into to the lubricating oil intake part 61. Thus, when the entire lubricating oil remaining in the lubricating oil intake part 61 is discharged to the lubricating oil discharge part 65, the engine is stopped. In this manner, the engine is prevented from being driven when the lubricating oil is not supplied to the sliding sections or the lubrication sections.
Because the suction port 62 is opened at the central part both in the direction along the crankshaft 21 and in the direction perpendicular to the crankshaft 21, the engine is stopped when the rammer 10 is tilted in any of the four directions, i.e., to the front, rear, left and right, or tilted largely to the extent that it almost rolls over. Similarly, the engine is stopped from being continuously driven after the engine is started while the rammer 10 rolls over in any of the directions.
When replacing the filter 57 or discharging the lubricating oil L of the oil pan 51, the sealing plug 58 is removed from the crankcase 20. Because the sealing plug 58 is removed from below the crankcase 20 when the rammer 10 is set upright, the lubricating oil L within the oil pan 51 is discharged to the outside through the lubricating oil suction pipe 59 and the intake-side communication hole 56. The lubricating oil suction pipe 59 is disposed preferably in the bottom part of the oil pan 51 in order to use the lubricating oil suction pipe 59 for discharging the lubricating oil. An oil feeding plug 71 for injecting the lubricating oil into the oil pan 51 is detachably installed in the crankcase 20. The lubricating oil L is injected into the oil pan 51 with the oil feeding plug 71 removed from the crankcase 20.
The present invention is not limited to the embodiments described above, and various changes can be made within the scope of the present invention. The driving unit mounted with the general-purpose engine is not limited to the rammer 10 illustrated in the drawings. The present invention can be applied to another driving unit such as a power generator.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-094583 | Apr 2010 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5014820 | Evans | May 1991 | A |
| 5076250 | Sasaki et al. | Dec 1991 | A |
| 5531290 | Furuichi et al. | Jul 1996 | A |
| 5669349 | Iwata et al. | Sep 1997 | A |
| 5846102 | Nitta et al. | Dec 1998 | A |
| 6626138 | Sayama et al. | Sep 2003 | B2 |
| 6742994 | Hironaka et al. | Jun 2004 | B2 |
| 6772725 | Inaba et al. | Aug 2004 | B2 |
| Number | Date | Country |
|---|---|---|
| 4-241713 | Aug 1992 | JP |
| 9-49414 | Feb 1997 | JP |
| 2713765 | Oct 1997 | JP |
| 3122696 | May 2006 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20110253093 A1 | Oct 2011 | US |
