JP4217098B2 - Multi-cylinder engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, an upper crankcase half is connected to a cylinder block having a plurality of cylinder sleeves in series, and the upper crankcase half and a lower crankcase half joined to the upper crankcase half A plurality of upper journal support walls and lower journal support walls that cooperate to support a plurality of crank journals of the crankshaft are integrally formed on the upper crankcase half and the lower crankcase half. The upper journal support wall is provided with a breathing hole that communicates between a plurality of crank chambers in the crankcase partitioned by the upper and lower journal support walls, and the upper journal support wall is formed in the cylinder sleeve. An oil jet that injects oil toward the inner wall of the piston that moves up and down is attached. In the multi-cylinder system, the adjacent crank chambers breathe each other through the breathing holes while the engine is running to cancel out pressure fluctuations in both crank chambers and to cool the piston with the oil injected from the oil jet. It relates to engine improvements.
[0002]
[Prior art]
Such a multi-cylinder engine is already known as disclosed, for example, in Patent Document 1 below.
[0003]
[Patent Document 1]
JP-A-10-169438 [0004]
[Problems to be solved by the invention]
By the way, in the multi-cylinder engine disclosed in the above publication, since the oil jet is arranged in the breathing hole, if the momentum of the oil jetted from the oil jet is weak, the direction is caused by the breathing air flow going back and forth through the breathing hole. Since it may be disturbed and may not reach the target location on the inner wall of the piston, conventionally, the oil injection pressure from the oil jet is always increased or the amount of jetting is increased so that the jetted oil is not affected by the breathing air flow. However, it has been forced to increase the size of the oil pump that pumps oil to the oil jet and increase the power consumption associated with it.
[0005]
The present invention has been made in view of such circumstances, and it is possible to reliably cool the piston by allowing the oil injected from the oil jet to reach a predetermined position on the inner wall of the piston without being obstructed by the breathing airflow. Another object of the present invention is to provide the multi-cylinder engine that can improve the breathing function of the breathing hole.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, an upper crankcase half is connected to a cylinder block having a plurality of cylinder sleeves in series, and the upper crankcase half is joined to the upper crankcase half. The lower crankcase half comprises a crankcase, and the upper crankcase half and the lower crankcase half include a plurality of upper journal support walls for supporting a plurality of crank journals of the crankshaft in cooperation. The lower journal support wall is formed integrally with each other, and the upper journal support wall is provided with a breathing hole communicating between a plurality of crank chambers in the crankcase partitioned by the upper and lower journal support walls. The oil is directed toward the inner wall of the piston that moves up and down in the cylinder sleeve. A multi-cylinder engine attached oil jets morphism, the upper journal support walls, characterized in that a least two breathing holes arranged across the extension axis of the oil jet.
[0007]
According to the above feature, the two breathing holes of the upper journal support wall are arranged so as to sandwich the extension axis of the oil jet, so that the breathing air flow flowing through each breathing hole disturbs the direction of the jet oil from the oil jet. Therefore, even if the oil injection pressure and the injection amount from the oil jet are not increased, the injection oil can reach a predetermined position on the inner wall of the piston, and the cooling can be performed reliably. Therefore, it is possible to reduce the size of the oil pump that pumps oil to the oil jet and to reduce the power consumption.
[0008]
In addition, by using a plurality of breathing holes in each upper journal support wall, the stress of each upper journal support wall is dispersed over a wide range, and the overall opening area of the breathing hole is ensured to be large. A smooth breathing action can be obtained, and the stress can be distributed over a wide range of each upper journal support wall, so that the thickness of each upper journal support wall can be reduced and the weight of the crankcase can be reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on preferred embodiments of the present invention shown in the drawings.
[0010]
1 is a side view of a multi-cylinder engine according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line 2-2 in FIG. 1, FIG. 3 is a sectional view taken along line 3-3 in FIG. FIG. 5 is a sectional view taken along line 5-5 of FIG.
[0011]
First, in FIGS. 1 to 3, reference numeral E denotes a four-cycle / multi-cylinder engine to which the present invention is applied, specifically an in-line four-cylinder engine. That is, the cylinder block 1 of the engine E is cast with four cylinder sleeves 2, 2,... In series, and the upper crankcase half 3a is integrally formed below the cylinder sleeves 2, 2,. . The lower crankcase half 3b is coupled to the lower surface of the upper crankcase half 3a by bolts, and the crankcase 3 that accommodates and supports the crankshaft 5 is constituted by both the crankcase halves 3a and 3b. .. Are connected to the four crank pins 5p, 5p... Of the crankshaft 5 via connecting rods 7, 7,. The two crankpins 5p and 5p adjacent to each other on both ends of the crankshaft 5 have a phase difference of 180 °, but the two crankpins 5p and 5p adjacent to each other at the center have the same phase.
[0012]
A cylinder head 9 equipped with a pair of intake valves 8i, 8i and exhaust valves 8e, 8e corresponding to the cylinder sleeves 2 is connected to the upper surface of the cylinder block 2 by bolts. A valve operating mechanism 11 for opening and closing the intake and exhaust valves 8i, 8i; 8e, 8e is provided in a valve operating chamber 11 defined between the head cover 10 to be joined, and the mechanism 12 is time-controlled. The crankshaft 5 is connected via a transmission device 13. A transmission chamber 14 that houses the timing transmission 13 is formed at one end of the cylinder block 2 and the cylinder head 9.
[0013]
A rotor 16a of a generator 16 is attached to the end of the crankshaft 5 opposite to the timing transmission device 13.
[0014]
A shift input shaft 20 disposed in parallel with the crankshaft 5 is attached to the upper crankcase half 3a, and a shift output shaft 21 is sandwiched between the upper and lower crankcase halves 3a and 3b. A plurality of speed change gear trains 21 _{1 to} 21 n (see FIG. 2) are arranged between the input shaft 20 and the speed change output shaft 21 to constitute the transmission 23. A clutch 24 is attached to an end of the transmission input shaft 20 on the timing transmission device 13 side, and a crankshaft 5 is connected to the input side of the clutch 24 via a primary reduction gear train 25.
[0015]
As shown in FIGS. 1, 4 and 5, in order to support all five crank journals 5j, 5j... Of the crankshaft 5 via bearing bushes 19, 19,. The upper journal support walls 17, 17... And the lower journal support walls 18, 18... Are integrally formed on the crankcase half 3b, respectively. The upper journal support wall 17 and the lower journal support wall 18 facing each other. Are arranged so as to sandwich the corresponding crank journal 5j, and are coupled by a pair of fastening bolts 30 and 30 (see FIG. 4).
[0016]
An oil pan 31 (see FIGS. 1 and 3) is joined to the lower end of the upper crankcase half 3b. Lubricating oil stored in the oil pan 31 is sucked up through an oil strainer 33 by an oil pump 32, filtered by an oil filter 34, and then pumped to an oil gallery 35. The oil pump 32 is driven from the output side of the primary reduction gear train 25 via the chain 26 (see FIG. 2), and the oil filter 34 is mounted on the front surface of the upper crankcase half 3a.
[0017]
The oil sent to the oil gallery 35 is supplied to the crank journals 5j, 5j... And the valve mechanism 12 through a plurality of branch paths 36, 36.
[0018]
As shown in FIGS. 2 and 4, the remaining four upper journal support walls 17, 17,... Except for the uppermost one upper journal support wall 17, have four pistons 6, 6.. The oil jets 37, 37... That direct the nozzle holes to predetermined positions on the inner wall are attached, and the oil sent to the oil gallery 35 is also injected into the inner walls of the pistons 6, 6. Cool down.
[0019]
The inside of the crankcase 3 is divided into four crank chambers 4, 4... By five upper and lower journal support walls 17, 17,..., 18, 18, and adjacent to each upper journal support wall 17. A plurality (two in the illustrated example) of circular breathing holes 38 and 38 (see FIG. 5) are provided to communicate with the crank chambers 4 and 4.
[0020]
At this time, as clearly shown in FIG. 4, the two breathing holes 38 are arranged on both sides so as to sandwich the extension axis 37a of the oil jet 37 provided in each corresponding upper journal support wall 17. Is done. These breathing holes 38 are formed by core pins when the cylinder block 2 is cast, or are formed by machining after casting.
[0021]
Next, the operation of the first embodiment will be described.
[0022]
The two crank pins 5p and 5p adjacent to each other on both ends of the crankshaft 5 have a phase difference of 180 ° from each other. Therefore, during the operation of the engine E, the two corresponding to the two crank pins 5p and 5p. The pistons 6 and 6 move up and down in opposite directions. Therefore, as the pistons 6 and 6 are moved up and down, the direction of pressure fluctuations occurring in the two crank chambers 4 and 4 corresponding to them is also reversed. Since the journal support walls 17 communicate with each other via the breathing holes 38, 38, the pressure fluctuations in the crank chambers 4, 4 can be offset by performing the breathing between them. As a result, the lifting resistance due to the back pressure of all the pistons 6, 6... Can be eliminated.
[0023]
In particular, since each upper journal support wall 17 is provided with a plurality of breathing holes 38, 38, the total opening area of the breathing holes 38, 38 is distributed while the stress of each upper journal support wall 17 is dispersed over a wide range. To ensure a smooth breathing action of the crank chambers 4 and 4, and by distributing stress over a wide area of each upper journal support wall 17, the thickness of each upper journal support wall 17 can be reduced. As a result, the weight of the crankcase 3 can be reduced.
[0024]
On the other hand, the oil jet 37 provided on each upper journal support wall 17 injects the oil fed from the oil gallery 35 toward the inner wall of the adjacent piston 6 and cools it. At this time, since the two breathing holes 38, 38 of each upper journal support wall 17 are arranged on both sides of the axis 37a of the oil jet 37, the breathing airflow flowing back and forth through the breathing holes 38, 38 is caused by the oil jet 37. Therefore, the direction of the injected oil from the oil jet 37 is not disturbed, and therefore the injected oil is supplied to the predetermined inner wall of the piston 6 without specially increasing the oil injection pressure from the oil jet 37 or increasing the oil injection amount. The oil pump 32 can be reliably cooled, and as a result, the oil pump 32 that pumps oil to the oil jet 37 can be downsized and the power consumption thereof can be reduced.
[0025]
The present invention is not limited to the above embodiments, and various design changes can be made without departing from the scope of the invention. For example, since an engine having two or more cylinders in series is an object of application of the present invention, the type of the engine such as a V type or a horizontally opposed type is not limited.
[0026]
【The invention's effect】
As described above, according to the present invention, the upper crankcase half is connected to the cylinder block having a plurality of cylinder sleeves in series, and the upper crankcase half and the lower crankcase joined to the upper crankcase half. The crankcase halves constitute a crankcase, and the upper and lower crankcase halves have a plurality of upper journal support walls and a lower journal for supporting a plurality of crank journals of the crankshaft in cooperation. A support wall is formed integrally with each other. The upper journal support wall is provided with a breathing hole that communicates between a plurality of crank chambers in the crankcase partitioned by the upper and lower journal support walls. , Inject oil toward the inner wall of the piston that moves up and down in the cylinder sleeve In a multi-cylinder engine with an oil jet, at least two breathing holes are provided in the upper journal support wall with the extension axis of the oil jet in between. The oil direction can be prevented from being disturbed, and therefore, the injected oil can reach a predetermined position on the inner wall of the piston without particularly increasing the oil injection pressure and the injection amount from the oil jet, thereby ensuring the cooling. As a result, it is possible to reduce the size of the oil pump that pumps oil to the oil jet and to reduce the power consumption. In addition, by using a plurality of breathing holes, the stress of each upper journal support wall can be dispersed over a wide range, and the overall opening area of the breathing holes can be secured to obtain a smooth breathing action of the crank chamber. At the same time, the wall thickness of the upper journal support wall can be reduced, and the weight of the crankcase can be reduced.
[Brief description of the drawings]
1 is a side view of a multi-cylinder engine according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. Enlarged view of essential parts [Fig. 5] Sectional view taken along line 5-5 in Fig. 4
E ... Engine 1 ... Cylinder block 2 ... Cylinder sleeve 3 ... Crankcase 3a ... Upper crankcase half 3b ... Lower crankcase half 4 ... Crank chamber 5 ... Crank shaft 5j ... Crank journal 5p ... Crank pin 6 ... Piston 17 ... Upper journal support wall 18 ... Lower journal support wall 37 ... Oil jet 37a ... Oil jet extension axis 38 ... Breathing hole

Claims (1)

An upper crankcase half (3a) is connected to a cylinder block (1) having a plurality of cylinder sleeves (2) in series, and the upper crankcase half (3a) and the upper crankcase half (3a) The crankcase (3) is composed of the lower crankcase half (3b) joined to the upper crankcase half (3a) and the lower crankcase half (3b). A plurality of upper journal support walls (17) and a lower journal support wall (18) for supporting a plurality of crank journals (5j) in cooperation with each other are integrally formed. And a breathing hole (3) communicating between the plurality of crank chambers (4, 4) in the crankcase (3) partitioned by the lower journal support walls (17, 18) In the multi-cylinder engine, the upper journal support wall (17) is provided with an oil jet (37) for injecting oil toward the inner wall of the piston (6) that moves up and down in the cylinder sleeve (2). ,
The multi-cylinder engine, wherein the upper journal support wall (17) is provided with at least two breathing holes (38) arranged with an extension axis (37a) of the oil jet (37) interposed therebetween.

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