JP2017503968A - Timing system for 2-cylinder engine - Google Patents

Abstract

The present invention relates to a two-cylinder engine with two separate cylinder heads each having at least one camshaft. The engine further includes two drive means for transmitting torque between the crankshaft (4) and one of the camshafts (9, 10; 9 ′, 10 ′), and further includes a primary stage, a crankshaft The two reverse rotation shafts (21, 22) each driven by (4) and driving one of the transmission means are provided, and the two transmission means are formed of the same mechanical component. [Selection] Figure 1

Description

  The present invention relates to the field of two-cylinder engines, and more particularly to a flat two-cylinder or “flat twin” type engine in which a camshaft is housed in a cylinder head.

  In a known manner, such an engine has two separate engine tops. Each engine upper end includes a cylinder / piston / cylinder head assembly and a timing drive.

  For example, US Pat. No. 2,749,893 is known in the prior art. This patent describes the first example of a “boxer” type two-cylinder engine with two counter-rotating shafts having a pair of bevel gears. The crankshaft drives an intermediate shaft provided with two bevel gear wheels. Each gear wheel drives a shaft via a pair of bevel gears. These axes are arranged perpendicular to the crankshaft in each of the two mutually offset planes.

  Each of these shafts drives the exhaust camshaft via a pair of bevel gears. Another shaft perpendicular to the intermediate shaft and the crankshaft drives the intake camshaft.

  British Patent GB2 392 476 describes another example of a multi-cylinder engine having a timing portion in the central plane of the cylinder. This solution is not compatible with a two cylinder engine.

  European Patent EP 1 717 425 describes an internal combustion engine having a plurality of cylinder banks with a V-shaped configuration and a drive mechanism for driving a valve by two idler shafts. The first idler shaft is designed to drive the cam shaft of the valve of the first bank via the first belt. The second idler shaft drives the cam shaft of the second bank valve via the second belt.

  This combined drive system for driving the camshaft allows the cylinder head to be shorter and smaller. The intermediate shaft is driven by a crankshaft through a gear. A chain connects the intermediate shaft to two gear wheels or sprockets housed in the cylinder head, which in turn drive the camshaft. The chain receives a guide part or guide shoe together with the tensioner.

  The crankshaft drives the balancer intermediate shaft with which two timing gear wheels or timing sprockets mesh (to have the same engine top part (cylinder head and cylinder), they are reversed with respect to the rear cylinder) Mesh on both sides of the shaft). As in the case of a 4-stroke engine, the camshaft must rotate at half the speed of the crankshaft. As a result, with chain drive control, the overhead camshaft gear wheel or sprocket will have a diameter twice that of the gear wheel or sprocket constrained to rotate with the crankshaft. The diameter of the gear wheel or sprocket on the crankshaft is directly related to the inner diameter of the bearing (journal).

  This structure includes a cascade of gear wheels or sprockets. Assembly is very complex because it is necessary to adjust the clearance between the gear wheel or sprocket while taking into account all gasket collapse. There is a complex solution chosen by Suzuki engineers, from the intermediate shaft (which directly drives the water pump rotor fixed at the end and rotates at half the speed of the crankshaft) Two gear wheels on camshaft with chain driven to gear wheel or idler sprocket (at the same level as the cylinder head gasket plane) and then incorporating springs for clearance or play take-up and shock absorption Or with a gear wheel or sprocket that distributes motion in the opposite direction to the sprocket. Thus, the gear wheel or sprocket can be made much smaller than a conventional gear.

  The camshaft gear and primary transmission gear wheel or sprocket are two parts and have springs to absorb clearance or play and to reduce machine noise.

  In addition, the chain tensioner system is less problematic because the chain is not so long. Suzuki attaches the tensioner with a set screw having two threads (the counterclockwise thread on the end and the clockwise thread on the clamping bearing surface), so that the tensioner is compressed for installation. It becomes possible to maintain. A shorter stroke also makes it possible to reduce the height of the cylinder and to make the block stand out small.

  Solutions known in the prior art implement a number of different mechanical components for each of the engine tops. This increases the cost of manufacturing and maintaining the engine.

  The object of the present invention is to transmit these torques from the crankshaft to each one camshaft, including two separate cylinder heads each having at least one camshaft in their most general sense. A two-cylinder engine further comprising two drive means for driving, further comprising a primary stage having two counter-rotating shafts, each driven by a crankshaft, each of which drives one of the transmission means, The transmission means is to improve by providing a two-cylinder engine characterized in that it is composed of identical mechanical components.

  The solution achieved by interposing a primary stage containing two counter-rotating shafts makes it possible to make the two engine upper ends completely symmetrical, with the same transmission configuration for both engine upper ends Makes it possible to use elements.

  Advantageously, each of the drive means has a longitudinal central plane, which is located on the opposite side of the longitudinal plane intersecting the crank pin at the upper end of the engine containing the cylinder head with respect to the central plane of the engine. To do.

  Preferably, the primary stage includes an idler gear wheel driven by a gear wheel constrained to rotate with the crankshaft, the idler gear wheel driving the first timing axis and the second timing axis being A gear wheel driven by a gear wheel constrained to rotate with the first timing shaft is provided.

  Advantageously, each transmission means comprises a gear wheel constrained to rotate with the timing shaft, a timing chain, at least one camshaft driven by a sprocket, and tensioner means for tensioning the chain. However, these components are the same in both timing means.

  In the first embodiment, at least one of the timing shafts drives an oil pump.

  In the second embodiment, at least one of the timing axes drives a water pump.

  Advantageously, the primary stage gives a gear ratio 1 / N and the drive means gives a gear ratio 1 / M, where N is in the range 1.5 to 2.5 and the total gear ratio is 1. / 2.

  In an advantageous variant embodiment, the axis of symmetry of the cylinder head is parallel.

  The invention can be better understood on reading the following description of non-limiting embodiments given with reference to the accompanying drawings.

It is a front perspective view of the engine of the present invention. It is a top view of the engine. It is a front view of the engine.

  In a known manner, the engine of the present invention includes a Maekawa engine upper end (1) and a rear engine upper end (2). In the example to be described, the upper end parts (1, 2) of the engine are aligned so as to form a flat two-cylinder structure inclined at an angle of 25 ° with respect to the horizontal axis.

  The engine lower end (3) including the crankshaft (4) is accommodated between the two engine upper ends (1, 2). The connecting rods (5, 6) are laterally offset from each other and are symmetric with respect to the longitudinal central plane of the engine. These support the pistons (7, 8).

  Each engine upper end (1, 2) includes an exhaust camshaft (9, 9 ') and an intake camshaft (10, 10'). These camshafts (9, 9 ′; 10, 10 ′) are constrained to rotate with their respective sprockets (11, 12; 11 ′, 12 ′) driven by their respective chains (13, 13 ′). Has been.

  Each of the chains (13, 13 ') is driven upstream by a primary shaft sprocket (14, 14'). Tension and guidance are provided by a fixed shoe (15, 15 ') and a movable shoe (16, 16').

  The movable shoe (16, 16 ') is pressed against the chain (13, 13') by a hydraulic tensioner (not shown).

The pair of mechanical components of the two engine upper ends (1, 2) is identical. That is,
The exhaust camshafts 9 and 9 'are exactly the same,
The intake camshafts 10 and 10 'are exactly the same,
The sprockets 11 and 11 ′ and the sprockets 12 and 12 ′ are exactly the same,
The chains 13 and 13 'are exactly the same,
The fixed shoe (15, 15 ′) and the movable shoe (16, 16 ′) are exactly the same.

  The engine lower end (3) includes a crankshaft (4) that supports a drive timing gear wheel (17). This drive gear wheel (17) has 26 teeth. This drives the idler gear wheel (18), which in the example described has 36 teeth.

  The idler gear wheel (18) then drives a front shaft gear wheel (19) having N teeth, in the example shown having 36 teeth.

  This front shaft gear wheel (19) then drives a rear shaft gear wheel (20) having the same number of teeth, ie 36 teeth in the example described.

  The front shaft (21) is provided with a front drive chain sprocket (14) having N / 2 teeth, in the example described having 18 teeth.

  Similarly, with respect to the rear engine lower end, the rear shaft (21 ') has a rear drive chain sprocket (14') having N / 2 teeth, in the example described having 18 teeth.

  The chains (13, 13 ′) pass around the drive sprockets (14, 14 ′), and the exhaust camshaft sprockets (11, 11 ′) and the intake camshaft sprockets (12, 12) of the front cylinder head and the rear cylinder head. ') To drive.

  It should be noted that although a chained timing section is proposed in this description, the term chain should be understood to include all known options such as timing belts.

  FIG. 2 shows a plan view. The engine has a vertical main longitudinal central plane (23) corresponding to the central plane of the motorcycle.

  The piston (7) and the front connecting rod (5) attached to the crankpin are half the thickness of the central flywheel (25) of the crankshaft (4) relative to the main longitudinal central plane (23) and the crankpin Having a longitudinal central plane (24) that is laterally offset by a distance N corresponding to half the thickness.

  The piston (8) and the rear connecting rod (6) attached to the second crankpin have a longitudinal central plane (26), which is the longitudinal central plane of the main longitudinal central plane (23). On the side opposite to the side where (24) is shifted, it is shifted laterally by a distance N corresponding to half the thickness of the central flywheel (25) of the crankshaft (4) and half the thickness of the crankpin.

  The longitudinal central plane (27) of the front timing chain (13) is located on the opposite side of the main central plane (23) from the side on which the central plane (24) is located. This positioning improves the lateral downsizing of the engine, and the front timing member is accommodated in a space that can be used by shifting the front engine upper end portion from the main central plane (23). It becomes possible.

  The longitudinal central plane (28) of the rear timing chain (13 ') is located on the opposite side of the main central plane (23) from the side on which the central plane (26) is located. This positioning improves the lateral downsizing of the engine, and the rear timing member is accommodated in a space that can be used because the upper end of the rear engine is displaced from the main central plane (23). It becomes possible to do.

  The front reverse rotation shaft (21) and the rear reverse rotation shaft (22) are configured such that the sprockets (14 and 14 ') are in one plane (27 and 28), respectively.

  The intersection of the axis of the front shaft (21) and the central plane (27) and the intersection of the axis of the rear shaft (22) and the central plane (28) are the crankshaft (4) and the main central plane (23). Symmetric with respect to the center of symmetry of the lower end of the engine defined by the intersection of

  Similarly, in the example of the flat two-cylinder engine, the front engine upper end (1) and the engine upper end (2) are in the main center plane (23) and intersect with the axis of the crankshaft (4). Axisymmetric with respect to (29).

  FIG. 3 is a front view of the engine.

Claims (8)

Two drives each for transmitting torque from the crankshaft (4) to one camshaft (9, 10; 9 ', 10') each comprising two separate cylinder heads having at least one camshaft A two-cylinder engine further comprising means,
The two-cylinder engine further includes a primary stage having two counter-rotating shafts, namely a front shaft (21) and a rear shaft (22),
The counter-rotating shaft is configured such that the sprockets (14, 14 ') are in respective central planes (27, 28);
The sprockets are driven by the crankshaft (4), each of which drives one of the transmission means;
The two-cylinder engine is characterized in that the two transmission means are composed of the same mechanical components.   Each of the driving means has a longitudinal center plane (27, 28), and the longitudinal center plane is a crank at the upper end of the engine including the cylinder head with respect to the center plane (23) of the two-cylinder engine. 2. The two-cylinder engine according to claim 1, characterized in that it lies on the opposite side of the longitudinal plane (24, 26) intersecting the pin.   The primary stage includes an idler gear wheel (18) driven by a gear wheel (17) constrained to rotate with the crankshaft (4), and the idler gear wheel (18) includes a gear wheel (19). ) To drive the first timing shaft (21), and the second timing shaft (22) is constrained to rotate with the first timing shaft (21). A two-cylinder engine according to claim 1 or 2, characterized in that a gear wheel (20) driven by is provided.   Each of the transmission means includes a gear wheel constrained to rotate with the timing shaft (21, 22), a timing chain (13, 13 ′), and a sprocket (11, 11 ′; 12, 12 ′). Having at least one camshaft (9, 10; 9 ', 10') to be driven and tensioner means for tensioning the timing chain, these components being identical in both timing means The two-cylinder engine according to any one of claims 1 to 3, wherein the two-cylinder engine is provided.   The two-cylinder engine according to any one of claims 1 to 4, characterized in that at least one of the timing shafts (21, 22) also drives an oil pump.   The two-cylinder engine according to any one of claims 1 to 5, characterized in that at least one of the timing shafts (21, 22) also drives a water pump.   The primary stage gives a gear ratio 1 / N and the drive means gives a gear ratio 1 / M, where N is in the range 1.5 to 2.5 and the total gear ratio is 1/2. The two-cylinder engine according to any one of claims 1 to 6, wherein the two-cylinder engine is characterized.   The two-cylinder engine according to any one of claims 1 to 7, wherein an axis of symmetry of the cylinder head is parallel.

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