Patent Description:
In related art, there is known a variable valve device in which a plurality of rocker arms are connected to each other to switch valve operations (see, for example, <CIT>). In a variable valve device described in <CIT>, a pair of rocker arms are arranged adjacent to each other, and a connecting pin is disposed in a pin hole of one rocker arm.

By pushing a part of the connecting pin into a pin hole of the other rocker arm, the pair of rocker arms are connected and a pair of valves are simultaneously operated. By pulling out the part of the connecting pin from the pin hole of the other rocker arm, a connected state of the pair of rocker arms is released, and only one valve is operated.

A spring pin for pushing back the connecting pin is disposed in the pin hole of the other rocker arm described in <CIT>. Therefore, the rocker arm is increased in a size, and a mass of a moving portion of a valve system is increased, so that the above variable valve device is not suitable for a high-speed engine. In this case, a structure is also conceivable in which a return pin is disposed in the pin hole of the other rocker arm and the spring pin is disposed outside the other rocker arm. The connecting pin is pushed in from one side by a drive pin, so that it is difficult to achieve a parallelism between the drive pin and the spring pin, and there is a possibility that components are worn due to partial contact.

An object of the present embodiment is to provide a variable valve device capable of preventing an increase in a size of a rocker arm and preventing wear due to partial contact between components.

An aspect of a present embodiment which can solve the above technical problem is a variable valve device capable of changing valve operations of an intake valve and an exhaust valve in a cylinder head, the variable valve device including a pair of cam housings separated in a predetermined direction in the cylinder head, a rocker shaft supported by opposing portions of the pair of cam housings, a plurality of rocker arms swingably supported by the rocker shaft, a connecting pin disposed in a pin hole of a rocker arm closer to one side in a predetermined direction, a return pin disposed in a pin hole of a rocker arm closer to the other side in the predetermined direction, a pressing member configured to cause the connecting pin to push the return pin to the other side, a repulsive member configured to cause the return pin to push back the connecting pin to one side, and an upper housing supported at both ends by upper surfaces of the pair of cam housings. In the variable valve device, the upper housing is formed with a first accommodation hole in which the pressing member is disposed on one side with respect to the rocker arm closer to one side and a second accommodation hole in which the repulsive member is disposed on the other side with respect to the rocker arm closer to the other side.

According to the variable valve device of the aspect of the present embodiment, when the return pin is pushed to the other side via the connecting pin by the pressing member, the connecting pin partially enters from the pin hole of the rocker arm closer to one side into the pin hole of the rocker arm closer to the other side, so that the plurality of rocker arms are connected. When the connecting pin is pushed back to the one side via the return pin by the repulsive member, the connecting pin is pulled out from the pin hole of the rocker arm closer to the other side, so that the connection of the plurality of rocker arms is released. In this way, a connected state and a released state of the plurality of rocker arms can be switched with a simple configuration. In addition, since the first accommodation hole and the second accommodation hole are formed in the upper housing, a parallelism between components is easily achieved, and wear due to partial contact between the components is prevented.

A variable valve device of one aspect of the present invention changes valve operations of an intake valve and an exhaust valve in a cylinder head. A pair of cam housings are separated in a predetermined direction in the cylinder head, and a rocker shaft is supported by opposing portions of the pair of cam housings. A plurality of rocker arms are swingably supported by the rocker shaft, a connecting pin is disposed in a pin hole of a rocker arm closer to one side in a predetermined direction, and a return pin is disposed in a pin hole of a rocker arm closer to the other side in the predetermined direction. When the return pin is pushed to the other side via the connecting pin by a pressing member, the connecting pin partially enters from the pin hole of the rocker arm closer to one side into the pin hole of the rocker arm closer to the other side, so that the plurality of rocker arms are connected. When the connecting pin is pushed back to one side via the return pin by a repulsive member, the connecting pin is pulled out from the pin hole of the rocker arm closer to the other side, so that the connection of the plurality of rocker arms is released. In this way, a connected state and a released state of the plurality of rocker arms can be switched with a simple configuration. In addition, an upper housing is supported at both ends by upper surfaces of the pair of cam housings. In the upper housing, the pressing member is disposed in a first accommodation hole on one side with respect to the rocker arm closer to one side, and the repulsive member is disposed in a second accommodation hole on the other side with respect to the rocker arm closer to the other side. Since the first accommodation hole and the second accommodation hole are formed in the upper housing, a parallelism between components is easily achieved, and wear due to partial contact between the components is prevented.

Hereinafter, an embodiment will be described in detail with reference to the accompanying drawings. <FIG> is a left side view of an engine and a vehicle body frame according to the present embodiment. <FIG> is a perspective view of an inside of a cylinder head according to the present embodiment. <FIG> is a perspective view of a variable valve device according to the present embodiment. In the following drawings, an arrow FR indicates a vehicle front side, an arrow RE indicates a vehicle rear side, an arrow L indicates a vehicle left side, and an arrow R indicates a vehicle right side. In addition, in the following description, a center side in a left-right direction of the cylinder head is referred to as one side, and an outer side in the left-right direction of the cylinder head is referred to as the other side.

As shown in <FIG>, a straddle-type vehicle is formed by mounting various components such as an engine <NUM> and an electrical system on a cradle-type vehicle body frame <NUM>. The vehicle body frame <NUM> includes a main tube <NUM> that extends rearward from an upper portion of a head pipe <NUM> and then bends downward, and a down tube <NUM> that extends downward from a lower portion of the head pipe <NUM> and then bends rearward. A rear end portion of the down tube <NUM> is joined to a lower end portion of the main tube <NUM> to form an installation space for the engine <NUM> inside the vehicle body frame <NUM>. A rear side of the engine <NUM> is supported by the main tube <NUM>, and a front side and a lower side of the engine <NUM> are supported by the down tube <NUM>.

The engine <NUM> is a parallel two-cylinder engine, and includes a crankcase <NUM>, a cylinder <NUM> provided on the crankcase <NUM>, a cylinder head <NUM> provided on the cylinder <NUM>, and a cylinder head cover <NUM> provided on the cylinder head <NUM>. A magnet cover <NUM> that covers a magnet (not shown) from a lateral side is attached to a left side surface of the crankcase <NUM>. A sprocket cover <NUM> that covers a drive sprocket (not shown) from a lateral side is attached to the rear of the magnet cover <NUM>. A clutch cover (not shown) that covers a clutch (not shown) from a lateral side is attached to a right side surface of the crankcase <NUM>.

A radiator <NUM> that radiates heat of cooling water of the engine <NUM> is disposed in front of the engine <NUM>. An oil control valve <NUM> that controls a hydraulic pressure to variable valve devices <NUM> is disposed on an outer surface of the cylinder head cover <NUM>. An oil is supplied to the oil control valve <NUM> from a main gallery of the crankcase <NUM> through an external pipe <NUM>. A valve chamber is formed inside the cylinder head <NUM> and the cylinder head cover <NUM>. The variable valve device <NUM> (see <FIG>) that changes valve operations of intake valves <NUM> (see <FIG>) and exhaust valves <NUM> (see <FIG>) by the hydraulic pressure is mounted on the valve chamber.

As shown in <FIG>, the engine <NUM> is a four-valve two-cylinder engine, and a cam chain <NUM> is disposed between two cylinders. The cam chain <NUM> is wound around a cam sprocket <NUM>, and the variable valve device <NUM> is disposed for each of the left and right cylinders with the cam sprocket <NUM> interposed therebetween. The variable valve device <NUM> is provided with a camshaft <NUM> that rotates integrally with the cam sprocket <NUM>. In the cylinder head <NUM>, cam housings 42a and 42b are separated in a left-right direction (a predetermined direction) for each cylinder, and the camshaft <NUM> is rotatably supported by mating surfaces of the cam housings 42a and 42b and the cylinder head <NUM>.

In the cylinder head <NUM>, four intake valves <NUM> (see <FIG>) are arranged behind the camshaft <NUM>, and four exhaust valves <NUM> are arranged in front of the camshaft <NUM>. The intake valve <NUM> is pressed in a valve-closing direction by a valve spring <NUM> (see <FIG>), and the exhaust valve <NUM> is pressed in a valve-closing direction by a valve spring <NUM>. A low-speed cam <NUM>, a high-speed cam <NUM>, and an exhaust cam <NUM> (all of which are shown in <FIG>) are formed on an outer circumferential surface of the camshaft <NUM>. Each of the cams <NUM> to <NUM> is formed in a plate-like shape with a cam ridge protruding from a part of a base circle. The cam ridge of the high-speed cam <NUM> is higher than that of the low-speed cam <NUM> so that a valve lift amount of the high-speed cam <NUM> is larger than that of the low-speed cam <NUM>.

A rocker shaft <NUM> on an intake side and a rocker shaft <NUM> on an exhaust side are supported by opposing portions of the cam housings 42a and 42b. The rocker shaft <NUM> on the intake side and the rocker shaft <NUM> on the exhaust side are located above the camshaft <NUM>, and the rocker shaft <NUM> on the intake side and the rocker shaft <NUM> on the exhaust side extend parallel to the camshaft <NUM>. In addition, left and right side walls of the cylinder head <NUM> are recessed in a concave shape, and a pair of plug covers <NUM> are arranged in recesses of the cylinder head <NUM>. The oil control valve <NUM> that supplies the oil to the variable valve device <NUM> is disposed behind the cylinder head <NUM>.

As shown in <FIG> and <FIG>, two types of rocker arms 51a and 51b (only one of each is shown in <FIG>) are swingably supported by the rocker shaft <NUM> on the intake side, and a rocker arm <NUM> (only one is shown in <FIG>) is swingably supported by the rocker shaft <NUM> on the exhaust side. The rocker arm 51a on the intake side and the rocker arm <NUM> on the exhaust side are formed in a seesaw shape having a force point and an action point, and the rocker arm 51b on the intake side serves as a force point of the rocker arm 51a. Both a left end of the rocker arm 51a on the intake side and a right end of the rocker arm <NUM> on the exhaust side are bifurcated.

A roller 53a that is in rolling contact with the low-speed cam <NUM> is rotatably supported at one end of the rocker arm 51a on the intake side, and a pair of intake valves <NUM> are connected to the other end of the rocker arm 51a which is bifurcated. A roller 53b that is in rolling contact with the high-speed cam <NUM> is rotatably supported at one end of the rocker arm 51b on the intake side, and the intake valve <NUM> is not connected to the other end of the rocker arm 51b. A roller <NUM> that is in rolling contact with the exhaust cam <NUM> is rotatably supported at one end of the rocker arm <NUM> on the exhaust side, and a pair of exhaust valves <NUM> are connected to the other end of the rocker arm <NUM> which is bifurcated. The rocker arms 51a and 51b are formed in a connectable manner.

When the engine rotates at a low speed and a medium speed, the rocker arms 51a and 51b are not connected. Therefore, the rocker arm 51a is swung by the low-speed cam <NUM>, and the rocker arm 51b is swung by the high-speed cam <NUM>. Since the pair of intake valves <NUM> are connected to the rocker arm 51a, the pair of intake valves <NUM> are moved according to rotation of the low-speed cam <NUM>. Since the cam ridge of the low-speed cam <NUM> is low, valve lift amounts of the pair of intake valves <NUM> are low. Since the intake valve <NUM> is not connected to the rocker arm 51b, the rocker arm 51b is idle according to rotation of the high-speed cam <NUM>.

When the engine rotates at a high speed, the rocker arms 51a and 51b are connected. Therefore, the rocker arms 51a and 51b are swung integrally by the high-speed cam <NUM>. Since the pair of intake valves <NUM> are connected to the rocker arm 51b via the rocker arm 51a, the pair of intake valves <NUM> are moved according to the rotation of the high-speed cam <NUM>. Since the cam ridge of the high-speed cam <NUM> is high, the valve lift amounts of the pair of intake valves <NUM> are high. In this way, by switching a connected state of the rocker arms 51a and 51b, the low-speed cam <NUM> and the high-speed cam <NUM> for moving the intake valves <NUM> are switched.

Each of the variable valve devices <NUM> is provided with a switching mechanism that switches between the connected state and a non-connected state of the rocker arms 51a and 51b according to the hydraulic pressure. A connecting pin <NUM> is disposed in a pin hole of the rocker arm 51b closer to one side (closer to a center) in a left-right direction (a predetermined direction) of the cylinder head <NUM>, and a return pin <NUM> is disposed in a pin hole of the rocker arm 51a closer to the other side (closer to an outer side) in the left-right direction of the cylinder head <NUM>. A hydraulic piston (a pressing member) <NUM> is disposed on one side with respect to the rocker arm 51b, and a spring pin (a repulsive member) <NUM> with a spring is disposed on the other side with respect to the rocker arm 51a.

The hydraulic piston <NUM> causes the connecting pin <NUM> to push the return pin <NUM> to the other side, and the spring pin <NUM> causes the return pin <NUM> to push back the connecting pin <NUM> to one side. By pushing the connecting pin <NUM> by the hydraulic piston <NUM>, a part of the connecting pin <NUM> enters the pin hole of the rocker arm 51a from the pin hole of the rocker arm 51b, so that the rocker arms 51a and 51b are connected. By pushing back the connecting pin <NUM> by the spring pin <NUM> via the return pin <NUM>, the part of the connecting pin <NUM> is pulled out from the pin hole of the rocker arm 51a, so that the connection of the rocker arms 51a and 51b is released.

The hydraulic piston <NUM> and the spring pin <NUM> are separated greatly in a left-right direction. In a case where the hydraulic piston <NUM> and the spring pin <NUM> are arranged as separate members, it is difficult to achieve a parallelism between the hydraulic piston <NUM> and the spring pin <NUM>, and there is a possibility that components are worn due to partial contact. Therefore, in the variable valve device <NUM> according to the present embodiment, an upper housing <NUM> is supported at both ends by upper surfaces of the cam housings 42a and 42b, and the hydraulic piston <NUM> and the spring pin <NUM> are arranged on the upper housing <NUM>. By arranging the hydraulic piston <NUM> and the spring pin <NUM> as the same member, the parallelism between the hydraulic piston <NUM> and the spring pin <NUM> is ensured.

When an oil is continuously injected from the camshaft <NUM> to lubricate the rocker arms 51a, 51b, and <NUM> by droplets of the oil, there is a possibility that an operating rotation speed of the variable valve device <NUM> cannot be obtained due to a decrease in a hydraulic pressure of the engine <NUM>. Further, adhesion of the oil to the cam increases a mechanical loss, and there is a possibility that important components are worn due to insufficient lubrication. Therefore, the upper housing <NUM> according to the present embodiment is formed in a ladder shape, and a lubricating oil is supplied from a bridge portion of the upper housing <NUM> along the rocker shafts <NUM> and <NUM> and the camshaft <NUM> to required locations of valve components.

Hereinafter, oil passages for lubrication and operation will be described with reference to <FIG>. <FIG> show a top view and a bottom view of the upper housing according to the present embodiment. <FIG> is a top view of the inside of the cylinder head according to the present embodiment. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line A-A. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line B-B. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line C-C. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line D-D. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line E-E. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line F-F. <FIG> is a cross-sectional view of the cylinder head in <FIG> taken along a line G-G. <FIG> is a schematic diagram of an operating passage and a short-cut passage according to the embodiment.

As shown in <FIG>, the upper housing <NUM> is formed in the ladder shape by housing fixing portions 71a and 71b extending in a front-rear direction and first to third bridge portions <NUM> to <NUM> extending in a left-right direction. The housing fixing portions 71a and 71b are fixed to the cam housings 42a and 42b, respectively (see <FIG>). The first bridge portion <NUM> connects the housing fixing portions 71a and 71b on the intake side of the cylinder head <NUM>. The second bridge portion <NUM> connects the housing fixing portions 71a and 71b between the intake side and the exhaust side of the cylinder head <NUM>. The third bridge portion <NUM> connects the housing fixing portions 71a and 71b on the exhaust side of the cylinder head <NUM>.

Attachment holes 75a and 75b are formed in each of the housing fixing portions 71a and 71b. The housing fixing portions 71a and 71b are respectively fixed to the cam housings 42a and 42b between the first bridge portion <NUM> and the second bridge portion <NUM> by the attachment holes 75a. The housing fixing portions 71a and 71b are respectively fixed to the cam housings 42a and 42b at both ends of the third bridge portion <NUM> by the attachment holes 75b. Bolt tightening locations are secured between the first and second bridge portions <NUM> and <NUM>, and bolt tightening locations are secured at both ends of the third bridge portion <NUM>, so that the upper housing <NUM> can be fixed to the cam housings 42a and 42b without increasing a size of the upper housing <NUM>.

The first bridge portion <NUM> extends along the rocker shaft <NUM> on the intake side (see <FIG>), and a lubricating passage <NUM> (see <FIG>) through which the lubricating oil passes is formed in the first bridge portion <NUM>. A plurality of supply holes 77c are formed in a lower surface of the first bridge portion <NUM>, and the plurality of supply holes 77c are located above contact locations between components. A pair of nozzles <NUM> protrude from the first bridge portion <NUM> to the intake side, and supply holes 77d at tips of the pair of nozzles <NUM> are located above the pair of intake valves <NUM> (see <FIG>). The first bridge portion <NUM> is connected to the housing fixing portions 71a and 71b via connecting portions 81a and 81b.

A hydraulic chamber (a first accommodation hole) <NUM> (see <FIG>) is formed in the connecting portion 81a which is a connecting location between the first bridge portion <NUM> and the housing fixing portion 71a. An accommodation hole (a second accommodation hole) <NUM> (see <FIG>) is formed in the connecting portion 81b which is a connecting location between the first bridge portion <NUM> and the housing fixing portion 71b. The hydraulic piston <NUM> (see <FIG>) serving as a hydraulic piston is disposed in the hydraulic chamber <NUM>, and the spring pin <NUM> (see <FIG>) is disposed in the accommodation hole <NUM>. The hydraulic chamber <NUM> and the accommodation hole <NUM> are formed coaxially, and the parallelism between the hydraulic piston <NUM> and the spring pin <NUM> is ensured. An operating oil is supplied to the hydraulic chamber <NUM> through a hydraulic circuit different from that for the lubricating oil.

The second bridge portion <NUM> extends along the camshaft <NUM> (see <FIG>), and a lubricating passage 76n (see <FIG>) is formed in the second bridge portion <NUM>. A plurality of supply holes 77e are formed in a lower surface of the second bridge portion <NUM>, and the plurality of supply holes 77e are located above the rocker arms 51a, 51b, and <NUM>. The third bridge portion <NUM> extends along the exhaust rocker shaft <NUM> on the exhaust side (see <FIG>). A pair of nozzles <NUM> protrude from the third bridge portion <NUM> to the exhaust side, and supply holes 77f (see <FIG>) at tips of the pair of nozzles <NUM> are located above the pair of exhaust valves <NUM> (see <FIG>).

An oil hole <NUM> is formed on the intake side of the housing fixing portion 71a, and an operating oil is supplied from the oil control valve <NUM> to the oil hole <NUM>. An oil groove is formed in a lower surface of the housing fixing portion 71a, and an operating passage (an oil passage) <NUM> and a short-cut passage (an oil passage) <NUM> through which the operating oil passes are formed by fixing the housing fixing portion 71a to the cam housing 42a. The operating passage <NUM> and the short-cut passage <NUM> communicate with the hydraulic chamber <NUM> (see <FIG>) in which the hydraulic piston <NUM> is disposed, and the operating oil is supplied from the oil control valve <NUM> to the hydraulic chamber <NUM> through the operating passage <NUM> and the short-cut passage <NUM>.

An oil groove is formed in a center of the housing fixing portion 71a, and a lubricating passage <NUM> is formed by fixing the housing fixing portion 71a to the cam housing 42a. The lubricating oil enters the lubricating passage <NUM> from a camshaft <NUM> side and is delivered to the second bridge portion <NUM>. An oil groove is formed in a lower surface of the housing fixing portion 71b, and a lubricating passage 76i is formed by fixing the housing fixing portion 71b to the cam housing 42b. The lubricating oil enters the lubricating passage 76i from the camshaft <NUM> side and is delivered to the first bridge portion <NUM>. In this way, hydraulic circuits for the lubricating oil and the operating oil are formed in the upper housing <NUM>.

As shown in <FIG>, the cylinder head <NUM> is fixed to the crankcase <NUM> via the cylinder <NUM> by using a plurality of head bolts <NUM>. A gap between the head bolt <NUM> on the exhaust side and a bolt hole forms a lubricating passage 76a, and a lubricating passage 76b extends obliquely from the lubricating passage 76a to the camshaft <NUM>. The lubricating oil is guided from the crankcase <NUM> to the periphery of the camshaft <NUM> through the lubricating passages 76a and 76b, and the lubricating oil is guided from the periphery of the camshaft <NUM> to a lubricating passage 76c in the camshaft <NUM>. Although the description is omitted, the lubricating oil in the lubricating passage 76c is used to lubricate peripheral components of the camshaft <NUM>.

The housing fixing portion 71a on one side (a center side in the left-right direction) is fixed to the cylinder head <NUM> via the cam housing 42a by using a pair of housing bolts <NUM>. Gaps between the pair of housing bolts <NUM> and bolt holes form lubricating passages 76d and 76e extending from the periphery of the camshaft <NUM> to the rocker shafts <NUM> and <NUM>, respectively. The lubricating oil is guided to lubricating passages 76f and <NUM> in the rocker shafts <NUM> and <NUM> through the lubricating passages 76d and 76e, respectively. The lubricating oil is supplied from a supply hole 77a of the rocker shaft <NUM> to the rocker arms 51a and 51b on the intake side, and the lubricating oil is supplied from a supply hole 77b of the rocker shaft <NUM> to the rocker arm <NUM> on the exhaust side.

As shown in <FIG>, the housing fixing portion 71b on the other side (an outer side in the left-right direction) is fixed to the cylinder head <NUM> via the cam housing 42b by using a pair of housing bolts <NUM>. A gap between the housing bolt <NUM> on the intake side and a bolt hole forms a lubricating passage <NUM> extending from the other end of the lubricating passage 76f of the rocker shaft <NUM> to the housing fixing portion 71b. A lubricating passage 76j extends obliquely from the lubricating passage 76i on a mating surface between the housing fixing portion 71b and the cam housing 42b to the first bridge portion <NUM>. The lubricating oil is guided from one end to the other end of the lubricating passage 76f, and the lubricating oil is guided to the lubricating passage <NUM> in the first bridge portion <NUM> through the lubricating passages <NUM> to 76j.

As shown in <FIG> and <FIG>, the lubricating oil is supplied from the plurality of supply holes 77c of the first bridge portion <NUM> to contact locations of the hydraulic piston <NUM>, the connecting pin <NUM>, the return pin <NUM>, and the spring pin <NUM>. Contact locations between pin components are lubricated to prevent wear. The pair of nozzles <NUM> protrude from the first bridge portion <NUM> to the intake side, and the supply holes 77d of the pair of nozzles <NUM> face an inner wall surface of the cylinder head cover <NUM>. The lubricating oil is blown against the inner wall surface of the cylinder head cover <NUM> from the supply holes 77d of the pair of nozzles <NUM>, and the lubricating oil is supplied to stem ends of the pair of intake valves <NUM> along the inner wall surface of the cylinder head cover <NUM>.

As shown in <FIG> and <FIG>, a lubricating passage <NUM> extends obliquely from the lubricating passage <NUM> on a mating surface between the housing fixing portion 71a and the cam housing 42a to the second bridge portion <NUM>. The oil is guided from the periphery of the camshaft <NUM> to the housing fixing portion 71a through the lubricating passage 76e, and the lubricating oil is guided to the lubricating passage 76n in the second bridge portion <NUM> through the lubricating passages <NUM> and <NUM>. The lubricating oil is supplied from the plurality of supply holes 77e of the second bridge portion <NUM> to the rollers 53a, 53b, and <NUM> of the rocker arms 51a, 51b, and <NUM>. The rocker arms 51a, 51b, and <NUM> are smoothly moved, and the pin components can be appropriately brought into contact with each other.

As shown in <FIG>, the housing fixing portion 71b is fixed to the cylinder head <NUM> via the cam housing 42b by using the pair of housing bolts <NUM>. A gap between the housing bolt <NUM> on the exhaust side and a bolt hole forms a lubricating passage 76o extending from the other end of the lubricating passage <NUM> of the rocker shaft <NUM> to the housing fixing portion 71b. The lubricating oil is guided from one end to the other end of the lubricating passage <NUM>, and the lubricating oil is guided to a lubricating passage 76r in the pair of nozzles <NUM> of the third bridge portion <NUM> through the lubricating passage 76o.

As shown in <FIG>, the pair of nozzles <NUM> protrude from the third bridge portion <NUM> to the exhaust side, and the supply holes 77f of the pair of nozzles <NUM> face a rib <NUM> of the cylinder head cover <NUM>. The rib <NUM> of the cylinder head cover <NUM> is located above the pair of exhaust valves <NUM>. The lubricating oil is blown against the rib <NUM> of the cylinder head cover <NUM> from the supply holes 77f of the pair of nozzles <NUM>, and the lubricating oil is supplied to stem ends of the pair of exhaust valves <NUM> along the rib <NUM> of the cylinder head cover <NUM>. In this way, hydraulic circuits for lubricating the valve components of the variable valve device <NUM> are formed in the upper housing <NUM>.

As shown in <FIG>, in the housing fixing portion 71a (see <FIG>), an upstream passage 87a of the operating passage <NUM> extends from the oil control valve <NUM> toward the camshaft <NUM>, and a downstream passage 87b of the operating passage <NUM> extends from the camshaft <NUM> toward the hydraulic piston <NUM>. A downstream end of the upstream passage 87a and an upstream end of the downstream passage 87b are positioned on the same circumference on the outer circumferential surface of the camshaft <NUM>. An oil groove <NUM> is formed in a circumferential direction on a circumference of the outer circumferential surface of the camshaft <NUM>. The oil groove <NUM> functions as an operating passage for supplying the operating oil to the hydraulic piston <NUM> together with the upstream passage 87a and the downstream passage 87b.

The oil is supplied from the oil control valve <NUM> to the hydraulic piston <NUM> only while the upstream passage 87a and the downstream passage 87b communicate with each other via the oil groove <NUM>. At this time, the oil groove <NUM> is formed such that the upstream passage 87a and the downstream passage 87b communicate with each other at an end timing of valve lift, and the upstream passage 87a and the downstream passage 87b are separated before the start of the valve lift. That is, the oil groove <NUM> is formed such that the oil starts to be supplied from the oil control valve <NUM> to the hydraulic piston <NUM> at the end timing of the valve lift, and the supply of the oil to the hydraulic piston <NUM> ends before the start of the valve lift.

Since the oil starts to be supplied to the hydraulic piston <NUM> at the end timing of the valve lift, a connecting operation of the rocker arms 51a and 51b is not hindered by the valve lift. In addition, since the connecting operation of the rocker arms 51a and 51b ends before the valve lift starts, the rocker arms 51a and 51b are not connected during the valve lift. Accordingly, as the camshaft <NUM> rotates, the oil is intermittently supplied from the oil control valve <NUM> to the hydraulic piston <NUM> through the operating passage <NUM>, and the rocker arms 51a and 51b can be smoothly connected via the connecting pin <NUM>.

The short-cut passage <NUM> extends directly from the oil control valve <NUM> to the hydraulic piston <NUM>. The short-cut passage <NUM> is formed shorter than the operating passage <NUM>. A stepwise oil supply structure with respect to the hydraulic piston <NUM> is formed such that the oil is supplied from the short-cut passage <NUM> to the hydraulic piston <NUM> after the oil is supplied from the operating passage <NUM> to the hydraulic piston <NUM>. Although the intermittent supply of the oil from the operating passage <NUM> alone may cause the hydraulic piston <NUM> to move, the hydraulic piston <NUM> is stably maintained by directly supplying the oil from the short-cut passage <NUM>.

A connecting operation of the variable valve device will be described with reference to <FIG> show explanatory views of the connecting operation of the variable valve device according to the present embodiment. In <FIG>, for convenience of description, reference signs in <FIG> are used as appropriate.

As shown in <FIG>, in the upper housing <NUM>, the hydraulic chamber <NUM> is formed in the connecting portion 81a on one side with respect to the rocker arm 51b, and the accommodation hole <NUM> is formed in the connecting portion 81b on the other side with respect to the rocker arm 51a. The hydraulic piston <NUM> is disposed in the hydraulic chamber <NUM>, and the spring pin <NUM> is disposed in the accommodation hole <NUM>. The hydraulic piston <NUM> is in contact with the connecting pin <NUM> in the rocker arm 51b, and the spring pin <NUM> is in contact with the return pin <NUM> in the rocker arm 51a. Center lines of the hydraulic piston <NUM> and the spring pin <NUM> coincide with each other, and wear due to partial contact between components is prevented.

When the engine rotates at a low speed, the oil is not supplied from the oil control valve <NUM> to the hydraulic chamber <NUM>. No pressing force is applied from the hydraulic piston <NUM> to the connecting pin <NUM>, and a spring force of the spring pin <NUM> is applied to the return pin <NUM>. The return pin <NUM> abuts against the rocker arm 51a, and the return pin <NUM> is positioned at an initial position. At this time, the other end <NUM> of the connecting pin <NUM> is in contact with one end <NUM> of the return pin <NUM> at a non-connecting position P1 in a gap between the rocker arms 51a and 51b. The other end <NUM> of the connecting pin <NUM> is located outside the rocker arm 51b, and the rocker arms 51a and 51b are separated from each other.

As shown in <FIG>, when an engine speed is increased to a predetermined speed or more, the oil starts to be supplied from the oil control valve <NUM> to the hydraulic chamber <NUM>. As the camshaft <NUM> rotates, the upstream passage 87a and the downstream passage 87b of the operating passage <NUM> intermittently communicate with each other through the oil groove <NUM>, and the oil is intermittently supplied from the operating passage <NUM> to the hydraulic piston <NUM>. At this time, the oil starts to be supplied at the end timing of the valve lift of the intake valve <NUM> so as not to hinder the connecting operation of the rocker arms 51a and 51b. Therefore, the hydraulic piston <NUM> is smoothly pushed out in an advancing direction with the oil from the operating passage <NUM>.

The connecting pin <NUM> is pushed in by the hydraulic piston <NUM>, and the spring pin <NUM> is moved to the other side via the return pin <NUM> by the connecting pin <NUM>. The other end <NUM> of the connecting pin <NUM> is moved to the other side from the non-connecting position P1 to a connecting position P2 in the rocker arm 51a. When a part of the connecting pin <NUM> enters a pin hole 55a of the rocker arm 51a, the rocker arms 51a and 51b are connected via the connecting pin <NUM>. A downstream end of the short-cut passage <NUM> is opened by the movement of the hydraulic piston <NUM>, and a position of the hydraulic piston <NUM> is maintained by continuous oil supply from the short-cut passage <NUM>.

As shown in <FIG>, when the engine speed falls below the predetermined speed, the oil is returned from the hydraulic piston <NUM> to the oil control valve <NUM>. The pushing of the connecting pin <NUM> by the hydraulic piston <NUM> is released, the return pin <NUM> is pushed back by a repulsive force of the spring pin <NUM>, and the connecting pin <NUM> is pushed back to the one side by the return pin <NUM>. The other end <NUM> of the connecting pin <NUM> is moved to the one side from the connecting position P2 to the non-connecting position P1. When the part of the connecting pin <NUM> is pulled out from the pin hole 55a of the rocker arm 51a, the connection of the rocker arms 51a and 51b is released.

As described above, according to the variable valve device <NUM> of the present embodiment, when the return pin <NUM> is pushed to the other side via the connecting pin <NUM> by the hydraulic piston <NUM>, the connecting pin <NUM> partially enters the pin hole of the rocker arm 51a from the pin hole of the rocker arm 51b, so that the rocker arms 51a and 51b are connected. When the connecting pin <NUM> is pushed back to the one side via the return pin <NUM> by the spring pin <NUM>, the connecting pin <NUM> is pulled out from the pin hole of the rocker arm 51a, so that the connection of the rocker arms 51a and 51b is released. In this way, the connected state and a released state of the rocker arms 51a and 51b can be switched with a simple configuration. In addition, since the hydraulic chamber <NUM> and the accommodation hole <NUM> are formed in the upper housing <NUM>, a parallelism between the components is easily achieved, and the wear due to the partial contact between the components is prevented.

In the present embodiment, the pair of rocker arms are provided on the intake side of the variable valve device, but a plurality of rocker arms may be provided on the intake side of the variable valve device. For example, three or more rocker arms may be provided on the intake side of the variable valve device.

In the present embodiment, the hydraulic piston is shown as an example of the pressing member, but the pressing member may be a member that causes the connecting pin to push the return pin to the other side.

In the present embodiment, the spring pin is shown as an example of the repulsive member, but the repulsive member may be a member that causes the return pin to push back the connecting pin to the one side.

In the present embodiment, the upper housing includes the first to third bridge portions, but the upper housing may be formed in a manner of being supported at both ends by the upper surfaces of the pair of cam housings.

In the present embodiment, the hydraulic chamber (the first accommodation hole) is formed in the connecting portion on the one side of the upper housing, but the hydraulic chamber may be formed on one side with respect to a rocker arm closer to one side in the upper housing. Similarly, the accommodation hole (the second accommodation hole) is formed in the connecting portion on the other side of the upper housing, but the accommodation hole may be formed on the other side with respect to a rocker arm closer to the other side in the upper housing.

In the present embodiment, a flange pin is used for the connecting pin and the return pin, but a straight pin may be used for the connecting pin and the return pin.

In the present embodiment, the seesaw-type rocker arm is shown as an example, but a type of the rocker arm is not particularly limited, and the rocker arm may be of a finger follower type.

In the present embodiment, the plurality of rocker arms are adjacent to each other, but the plurality of rocker arms may be separated from each other.

In the present embodiment, the operating passage and the short-cut passage are formed in the upper housing, but an oil passage capable of supplying the operating oil to the hydraulic piston may be formed in the cylinder head.

An exhaust device according to the present embodiment is not limited to the engine of the straddle-type vehicle described above, and may be adopted for an engine of another vehicle. The straddle-type vehicle is not limited to a motorcycle, and may be any vehicle on which an engine is mounted. The straddle-type vehicle is not limited to general vehicles on which a driver rides in a posture of straddling a seat, and includes a scooter-type vehicle on which the driver rides without straddling the seat.

As described above, a first aspect relates to a variable valve device (<NUM>) capable of changing valve operations of an intake valve (<NUM>) and an exhaust valve (<NUM>) in a cylinder head (<NUM>), the variable valve device including: a pair of cam housings (42a, 42b) separated in a predetermined direction in the cylinder head; a rocker shaft (<NUM>) supported by opposing portions of the pair of cam housings; a plurality of rocker arms (51a, 51b) swingably supported by the rocker shaft; a connecting pin (<NUM>) disposed in a pin hole of a rocker arm closer to one side in a predetermined direction; a return pin (<NUM>) disposed in a pin hole of a rocker arm closer to the other side in the predetermined direction; a pressing member (the hydraulic piston <NUM>) configured to cause the connecting pin to push the return pin to the other side; a repulsive member (the spring pin <NUM>) configured to cause the return pin to push back the connecting pin to one side; and an upper housing (<NUM>) supported at both ends by upper surfaces of the pair of cam housings, in which the upper housing is formed with a first accommodation hole (the hydraulic chamber <NUM>) in which the pressing member is disposed on one side with respect to the rocker arm closer to one side, and a second accommodation hole (the accommodation hole <NUM>) in which the repulsive member is disposed on the other side with respect to the rocker arm closer to the other side. According to this configuration, when the return pin is pushed to the other side via the connecting pin by the pressing member, the connecting pin partially enters from the pin hole of the rocker arm closer to one side into the pin hole of the rocker arm closer to the other side, so that the plurality of rocker arms are connected. When the connecting pin is pushed back to the one side via the return pin by the repulsive member, the connecting pin is pulled out from the pin hole of the rocker arm closer to the other side, so that the connection of the plurality of rocker arms is released. In this way, a connected state and a released state of the plurality of rocker arms can be switched with a simple configuration. In addition, since the first accommodation hole and the second accommodation hole are formed in the upper housing, a parallelism between components is easily achieved, and wear due to partial contact between the components is prevented.

In a second aspect according to the first aspect, the upper housing includes a pair of housing fixing portions (71a, 71b) fixed to the pair of cam housings, and a first bridge portion (<NUM>) that is located on an intake side of the cylinder head and connects the pair of housing fixing portions, and the first accommodation hole is formed in a connecting location (the connecting portion 81a) between one housing fixing portion and the first bridge portion, and the second accommodation hole is formed in a connecting location (the connecting portion 81b) between the other housing fixing portion and the first bridge portion. According to this configuration, a rigidity around the first accommodation hole and the second accommodation hole is increased, and a parallelism between the first accommodation hole and the second accommodation hole is easily achieved.

In a third aspect according to the second aspect, the first bridge portion is formed with a plurality of supply holes (77c) configured to allow a lubricating oil to be supplied to contact locations of the connecting pin, the return pin, the pressing member, and the repulsive member. According to this configuration, the contact locations of the connecting pin, the return pin, the pressing member, and the repulsive member can be lubricated to prevent the wear.

In a fourth aspect according to the second aspect or the third aspect, the first bridge portion is formed with a supply hole (77d) configured to allow a lubricating oil to be supplied to a stem end of the intake valve. According to this configuration, the stem end of the intake valve can be lubricated.

In a fifth aspect according to any one of the second aspect to the fourth aspect, the upper housing includes a second bridge portion (<NUM>) that is located between the intake side and an exhaust side of the cylinder head and connects the pair of housing fixing portions, and the pair of housing fixing portions are fixed to the pair of cam housings between the first bridge portion and the second bridge portion. According to this configuration, a rigidity of the upper housing can be increased by the second bridge portion. In addition, it is possible to secure bolt tightening locations between the first and second bridge portions and fix the upper housing to the cam housings without increasing a size of the upper housing.

In a sixth aspect according to the fifth aspect, the second bridge portion is formed with a plurality of supply holes (77e) configured to allow a lubricating oil to be supplied to the plurality of rocker arms. According to this configuration, the rocker arms can be lubricated. Since the rocker arms are smoothly moved, pin components can be appropriately brought into contact with each other.

In a seventh aspect according to any one of the second aspect to the sixth aspect, the upper housing includes a third bridge portion (<NUM>) that is located on an exhaust side of the cylinder head and connects the pair of housing fixing portions, and the pair of housing fixing portions are fixed to the pair of cam housings at both ends of the third bridge portion. According to this configuration, the rigidity of the upper housing can be increased by the third bridge portion. In addition, it is possible to secure bolt tightening locations at both ends of the third bridge portion and fix the upper housing to the cam housings without increasing the size of the upper housing.

In an eighth aspect according to the seventh aspect, the third bridge portion is formed with a supply hole (77f) configured to allow a lubricating oil to be supplied to a stem end of the exhaust valve. According to this configuration, the stem end of the exhaust valve can be lubricated.

In a ninth aspect according to any one of the second aspect to the eighth aspect, the pressing member is a hydraulic piston configured to be operated with a hydraulic pressure, and a mating surface of the pair of cam housings and the pair of housing fixing portions is formed with an oil passage (the operating passage <NUM>, the short-cut passage <NUM>) configured to allow an operating oil to be supplied to the hydraulic piston. According to this configuration, the oil passage can be formed in a compact manner using the mating surface of the pair of cam housings and the pair of housing fixing portions.

Although the present embodiment has been described, the above-described embodiment and modification may be combined entirely or partially as another embodiment.

Claim 1:
A variable valve device (<NUM>) capable of changing valve operations of an intake valve and an exhaust valve in a cylinder head, the variable valve device comprising:
a pair of cam housings (42a, 42b) separated in a predetermined direction in the cylinder head;
a rocker shaft (<NUM>) supported by opposing portions of the pair of cam housings;
a plurality of rocker arms (51a, 51b) swingably supported by the rocker shaft;
a connecting pin (<NUM>) disposed in a pin hole of a rocker arm closer to one side in a predetermined direction;
a return pin (<NUM>) disposed in a pin hole of a rocker arm closer to the other side in the predetermined direction;
a pressing member (<NUM>) configured to cause the connecting pin to push the return pin to the other side;
a repulsive member (<NUM>) configured to cause the return pin to push back the connecting pin to one side; and
an upper housing (<NUM>) supported at both ends by upper surfaces of the pair of cam housings, wherein
the upper housing is formed with a first accommodation hole (<NUM>) in which the pressing member is disposed on one side with respect to the rocker arm closer to one side and a second accommodation hole (<NUM>) in which the repulsive member is disposed on the other side with respect to the rocker arm closer to the other side.