Internal-combustion engines – Vibration compensating device – Balancing arrangement
Reexamination Certificate
1999-05-17
2001-05-22
Wolfe, Willis R. (Department: 3747)
Internal-combustion engines
Vibration compensating device
Balancing arrangement
C123S1960CP, C123S1950HC
Reexamination Certificate
active
06234133
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a balancer shaft supporting structure in an engine which includes a crankshaft disposed substantially vertically and clamped between dividing surfaces of a cylinder block and a crankcase, and to an engine hanger device i n an outboard engine system provided with an engine which includes a pair of balancer shafts in a cylinder block.
BACKGROUND ART
So-called vertically-disposed engines each including a crankshaft disposed vertically are known from Japanese Patent Application Laid-open Nos. 63-192918 and 4-337143, in which a balancer shaft is supported on the side of a crankcase (on the side opposite from the cylinder block with the crankshaft interposed therebetween).
In the vertically-disposed engine described in the above Japanese Patent Application Laid-open No. 4-337143, the crankshaft is clamped between dividing surfaces of the cylinder block and the crankcase. However, such an engine suffers from a problem that if the balancer shaft is supported on the side of the crankcase, a bolt for coupling the crankcase to the cylinder block interferes with the balancer shaft and for this reason, a limitation is produced in the layout of the bolt and balancer shaft. Especially, when the balancer shaft is longer in the axial direction of the crankshaft, the above problem is significant, and it is difficult to dispose the balancer shaft without bringing about an increase in size of the crankcase.
An engine for an outboard engine system with a crankshaft disposed vertically is known from the above Japanese Patent Application Laid-open No. 4-337143, which includes a pair of secondary balancer shafts. In addition, an engine for an outboard engine system with a crankshaft disposed vertically is known from Japanese Utility Model Application Laid-open No. 3-76799, which includes an engine hanger on an upper surface of a cylinder block.
In the engine described in the above Japanese Patent Application Laid-open No. 4-337143, the pair of secondary balancer shafts are supported in the crankcase coupled to a front surface of the cylinder block. For this reason, if an attempt is made to ensure a space for disposition of the secondary balancer shafts, there is a possibility that the crankcase may protrude forwards (namely, toward a hull), thereby hindering the layout of auxiliaries around the crankcase. The art described in the above Japanese Utility Model Application Laid-open No. 3-76799 includes no balancer shaft and hence, the relationship between the engine hanger and a balancer shaft is not described.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished with the above circumstances in view, and it is a first object of the present invention to ensure that a balancer shaft is disposed reasonably in a so-called vertically-disposed engine having a crankshaft disposed vertically.
It is a second object of the present invention to ensure that a pair of secondary balancer shafts and an engine hanger are disposed reasonably without bringing about an increase in size of an engine block.
To achieve the above first object, according to a first aspect and feature of the present invention, there is provided a balancer shaft supporting structure in an engine including a crankshaft disposed substantially vertically and clamped between dividing surfaces of a cylinder block and a crankcase, the crankcase being fastened to the cylinder block by bolts inserted from the side of the crankcase, characterized in that the structure includes balancer shafts connected to and driven by the crankshaft, the balancer shafts being supported substantially vertically in the cylinder block.
With the above arrangement, the balancer shaft connected to and driven by the crankshaft is supported substantially vertically in the cylinder block. Therefore, in fastening the crankcase to the cylinder block by bolts inserted from the side of the crankcase, there is not a possibility that the bolt may interfere with the balancer shaft, and hence, the degree of freedom in the layout of the balancer shaft is increased.
To achieve the first object, according to a second aspect and feature of the present invention, in addition to the first feature, there is provided a balancer shaft supporting structure in an engine characterized in that upper ends of the balancer shafts and an upper end of the crankshaft protrude upwards from an upper surface of the cylinder block, such protrusions of the balancer shafts and the crankshaft being connected together by a power transmitting means.
With the above arrangement, the upper ends of the balancer shafts and the upper end of the crankshaft protrude upwards from an upper surface of the cylinder block, and the protrusions of the balancer shaft and the crankshaft are connected together by a power transmitting means. Therefore, the power transmitting means can be disposed outside the cylinder block, whereby the maintenance of the power transmitting means can be facilitated.
To achieve the above first object, according to a third aspect and feature of the present invention, in addition to the second feature, there is provided a balancer shaft supporting structure in an engine characterized in that the power transmitting means is covered with a cover.
With the above arrangement, the power transmitting means can be protected from dusts or sea water by covering the power transmitting means with the cover.
To achieve the above first object, according to a fourth aspect and feature of the present invention, in addition to the third feature, there is provided a balancer shaft supporting structure in an engine characterized in that the cover is provided with a ventilating port.
With the above arrangement, since the cover is provided with a ventilating port, the ventilation in the cover can be conducted to prevent the rising of the temperature of the power transmitting means.
To achieve the above second object, according to a fifth aspect and feature of the present invention, an engine hanger device in an outboard engine system provided with an engine which includes a crankshaft disposed substantially vertically, and a pair of balancer shafts driven by the crankshaft through an endless transmitting band, characterized in that the pair of balancer shafts are supported on laterally opposite sides of a cylinder axis in a cylinder block; a tension pulley for applying a tension to the endless transmitting band disposed along an upper surface of the cylinder block is mounted on one side of the cylinder axis, and an engine hanger for hanging the outboard engine system along with the engine is mounted outside a loop provided by the endless transmitting band and on the other side of the cylinder axis.
With the above arrangement, the pair of balancer shafts are supported on the laterally opposite sides of the cylinder axis in the cylinder block; the tension pulley for applying the tension to the endless transmitting band disposed along the upper surface of the cylinder block is mounted on one side of the cylinder axis, and the engine hanger for hanging the outboard engine system along with the engine is mounted outside the loop provided by the endless transmitting band and on the other side of the cylinder axis. Therefore, the balancer shafts, the endless transmitting band, the tension pulley and the engine hanger can be disposed reasonably in the upper surface of the cylinder block, so that they do not interfere with one another, thereby providing a reduction in size of the cylinder block.
To achieve the above second object, according to a sixth aspect and feature of the present invention, in addition to the fifth feature, there is provided an engine hanger device in an outboard engine system characterized in that the tension pulley for applying the tension to the endless transmitting band for driving a cam shaft by the crankshaft and the tension pulley for applying the tension to the endless transmitting band for driving the balancer shafts are disposed in such a manner that at least portions thereof are vertically overlapped with each other.
With t
Sakata Shigekazu
Tsunoda Masaki
Arent Fox Kinter Plotkin & Kahn PLLC
Harris Katrina B.
Honda Giken Kogyo Kabushiki Kaisha
Wolfe Willis R.
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