A new type of internal combustion engine balance structure and internal combustion engine

Abstract

The present invention discloses a novel internal combustion engine balance structure and an internal combustion engine. The internal combustion engine includes a housing, a piston, a connecting rod, and a crankshaft. The novel internal combustion engine balance structure includes a balance weight, a first balance shaft, and a second balance shaft; the piston is slidably connected in the housing along the X direction; the crankshaft, the first balance shaft, and the second balance shaft are all rotatably connected to the housing; the rotation center O1 of the first balance shaft, the rotation center O0 of the crankshaft, and the rotation center O2 of the second balance shaft are arranged in sequence in the Y direction, and O0 is located on the extension line of the central axis of the piston; the balance weight is connected to the crankshaft; the first balance shaft is directly or indirectly drivingly connected to the crankshaft, and the second balance shaft is directly or indirectly drivingly connected to the crankshaft. The present invention can balance the first-order reciprocating inertia force and can avoid generating an unbalanced moment, thereby being able to reduce the vibration of the internal combustion engine and avoid the tipping of the internal combustion engine.

Description

Technical Field

[0001] The present invention relates to a novel internal combustion engine balance structure and an internal combustion engine. Background Art

[0002] At present, an internal combustion engine includes a piston, a connecting rod and a crankshaft. Taking a single-cylinder diesel engine as an example, the crankshaft includes a main journal, a crank arm and a connecting rod journal. The big end of the connecting rod is rotatably connected to the connecting rod journal, and the small end of the connecting rod is rotatably connected to the piston. When the piston reciprocates, the crankshaft is driven to rotate by the connecting rod. During operation, the internal combustion engine generates strong vibrations. The sources of vibration include the centrifugal inertia force generated by the rotational mass of the crankshaft and the connecting rod during rotational motion, and the reciprocating inertia force generated by the reciprocating mass of the piston and the connecting rod during reciprocating motion. Among them, a part of the actual mass of the connecting rod is converted to the small end of the connecting rod to obtain the reciprocating mass of the connecting rod, and another part of the actual mass of the connecting rod is converted to the big end of the connecting rod to obtain the rotational mass of the connecting rod. How to calculate the centrifugal inertia force and the reciprocating inertia force and how to convert the actual mass of the connecting rod can be found in "Analysis of Inertia Forces of Crank-Connecting Rod Mechanism" in the 5th issue of the 19th volume of the Journal of Changwei Teachers College, and the article number is 1008 - 4150(2000)05 - 0068 - 03.

[0003] The centrifugal inertia force is relatively easy to balance. It only needs to install a balance weight on the crankshaft so that the balancing force generated by the rotation of the balance weight cancels out the centrifugal inertia force. The reciprocating inertia force is more complex and usually includes a first-order reciprocating inertia force, a second-order reciprocating inertia force, a third-order reciprocating inertia force, etc. Since the reciprocating inertia forces above the second order account for a very small proportion, the industry usually only balances the first-order reciprocating inertia force. The first-order reciprocating inertia force accounts for about 70% of all reciprocating inertia forces and is the main source of reciprocating vibration. Therefore, after balancing the first-order reciprocating inertia force, the reciprocating vibration of the internal combustion engine can be effectively reduced.

[0004] Currently, for the first-order reciprocating inertia force F j usually a two-shaft balance mechanism is used. As Figure 1 shown, the two-shaft balance mechanism includes a first balance shaft and a second balance shaft. The first balance shaft and the second balance shaft have the same rotational speed and opposite rotational directions. The first balance shaft is located below the crankshaft, and the vertical distance between the first balance shaft and the crankshaft is L1. The second balance shaft is located above the crankshaft, and the vertical distance between the second balance shaft and the crankshaft is L2, and the first balance shaft is directly below the second balance shaft.

[0005] The centrifugal inertia force generated by the rotation of the first balance shaft is F1, the horizontal component of F1 is F 1x , and the vertical component of F1 is F 1yThe centrifugal inertial force generated by the rotation of the second balance shaft is F2, and the horizontal component of F2 is F 2x , and the vertical component of F2 is F 2y . Among them, the first balance shaft and the second balance shaft satisfy the following conditions: F 1y and F 2y are always equal and opposite in direction. Therefore, F 1y and F 2y cancel each other out; F 1x and F 2x are always equal and both are opposite to the first-order reciprocating inertial force F j . Therefore, F 1x and F 2x can balance the first-order reciprocating inertial force F j . In addition, the rotation center of the crankshaft is O0, and the action line of F j passes through point O0. Therefore, the moment of F j at point O0 is 0; the moments of F 1y and F 2y at point O0 cancel each other out because F 1x and F 2x are always equal. To make the moments of F 1x and F 2x at point O0 cancel each other out, L1 and L2 must be equal.

[0006] However, due to the narrow space inside the engine housing of the internal combustion engine and the need to install many components in the engine housing of the internal combustion engine, the arrangement positions of the first balance shaft and the second balance shaft are restricted by the housing size and surrounding components, and the situation where L1 is less than L2 often occurs. In this case, the moments of F 1x and F 2x at point O0 are not equal and cannot cancel each other out. Therefore, an unbalanced moment with a magnitude of (F 2x ·L2 - F 1x ·L1) is formed, and this unbalanced moment will cause the internal combustion engine to have a risk of tipping over and will increase the vibration of the internal combustion engine. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a new internal combustion engine balance structure, which can balance the first-order reciprocating inertial force and can avoid generating an unbalanced moment, thereby being able to reduce the vibration of the internal combustion engine and avoid the tipping over of the internal combustion engine.

[0008] To solve the above technical problem, the technical solution of the present invention is: a new internal combustion engine balance structure, the internal combustion engine includes an engine housing, a piston, a connecting rod and a crankshaft, and it includes a balance weight, a first balance shaft and a second balance shaft;

[0009] The piston is slidably connected in the housing along the X direction;

[0010] The crankshaft, the first balance shaft and the second balance shaft are all rotatably connected to the housing;

[0011] The rotation center O1 of the first balance shaft, the rotation center O0 of the crankshaft and the rotation center O2 of the second balance shaft are arranged in sequence in the Y direction, and O0 is located on the extension line of the central axis of the piston;

[0012] The balance weight is connected to the crankshaft;

[0013] The first balance shaft is directly or indirectly drivingly connected to the crankshaft, and the first balance shaft has the same rotational speed as the crankshaft and rotates in the opposite direction;

[0014] The second balance shaft is directly or indirectly drivingly connected to the crankshaft, and the second balance shaft has the same rotational speed as the crankshaft and rotates in the same direction;

[0015] One end of the connecting rod is rotatably connected to the piston at point A, and the other end of the connecting rod is rotatably connected to the crankshaft at point B, so that when the piston reciprocates along the X direction, the crankshaft is driven to rotate through the connecting rod, and the following relationship is satisfied during operation:

[0016] F p The direction of is along the direction from point B to point O0, and F p >F r ;

[0017] When the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively;

[0018] F0 + F2 = F1, and F1·L1 = F2·L2, and L1 < L2;

[0019] Among them, F0 is obtained by balancing F p balancing off F r obtaining, F p is the centrifugal inertial force generated by the rotation of the balance weight, F r is the sum of the centrifugal inertial force of the crankshaft and the centrifugal inertial force generated by the rotating mass of the connecting rod, F1 is the centrifugal inertial force generated by the rotation of the first balance shaft, F2 is the centrifugal inertial force generated by the rotation of the second balance shaft, L1 is the distance in the Y direction from the rotation center O0 of the crankshaft to the rotation center O1 of the first balance shaft, and L2 is the distance in the Y direction from the rotation center O0 of the crankshaft to the rotation center O2 of the second balance shaft.

[0020] Furthermore, the piston, the connecting rod, the crankshaft, the balance weight, the first balance shaft and the second balance shaft are arranged to satisfy:

[0021] F 0x + F 1x + F 2x = F j ; wherein, F 0x is the component force of F0 in the X direction, and F 1x is the component force of F1 in the X direction, and F 2x is the component force of F2 in the X direction, and F j is the sum of the first-order reciprocating inertia forces generated by the reciprocating masses of the piston and the connecting rod.

[0022] Further provided is a specific structure of the crankshaft. The crankshaft includes a main journal, a crank arm, and a connecting rod journal. The crank arm is connected to the main journal, the connecting rod journal is connected to the crank arm, the main journal is rotatably connected to the engine housing, a balance weight is connected to the crank arm, and one end of the connecting rod is rotatably connected to the connecting rod journal;

[0023] The second balance shaft includes a shaft body rotatably connected to the engine housing and an eccentric portion connected to the shaft body.

[0024] Further, the X direction is the horizontal direction, and the Y direction is the vertical direction;

[0025] The rotation center O1 of the first balance shaft is located directly below the rotation center O0 of the crankshaft;

[0026] The rotation center O2 of the second balance shaft is located directly above the rotation center O0 of the crankshaft.

[0027] Further, in order to save space inside the engine housing, the crankshaft and the first balance shaft are respectively rotatably connected inside the engine housing;

[0028] The second balance shaft is located outside the engine housing and is rotatably connected to the upper end portion of the engine housing.

[0029] Further, the crankshaft and the first balance shaft are connected by a gear pair for transmission.

[0030] Further, the crankshaft and the second balance shaft are connected by a transmission mechanism. The transmission mechanism includes a driving wheel, a driven wheel, and a transmission belt; wherein,

[0031] The driving wheel is directly or indirectly connected to the crankshaft;

[0032] The driven wheel is connected to the second balance shaft;

[0033] The transmission belt is connected to the driving wheel and the driven wheel so that when the crankshaft rotates, it drives the second balance shaft to rotate.

[0034] Furthermore, the novel internal combustion engine balance structure further includes a flywheel, the flywheel is connected to the crankshaft, and the driving wheel is connected to the flywheel.

[0035] Furthermore, the driving wheel, the driven wheel and the transmission belt are all located outside the engine housing;

[0036] Both the driving wheel and the driven wheel are synchronous belt wheels, the transmission belt is a synchronous belt, and the number of teeth on the driving wheel and the driven wheel is equal.

[0037] The present invention also provides an internal combustion engine, which includes the novel internal combustion engine balance structure as described above.

[0038] After adopting the above technical solution, the direction of the centrifugal inertial force is from the rotation center to the centroid. From the structural characteristics of the crankshaft, it can be known that the centrifugal inertial force F s generated by the rotation of the crankshaft is in the direction from point O0 to point B, and the magnitude of F s can be calculated according to the eccentric mass of the crankshaft, the eccentric radius of the crankshaft and the rotational speed of the crankshaft by the centrifugal force formula; among them, the eccentric mass of the crankshaft, the eccentric radius of the crankshaft and the rotational speed of the crankshaft are all known quantities, so F s is known.

[0039] When analyzing the inertial force of the connecting rod, it is necessary to use the mass substitution system to convert a part of the actual mass M c of the connecting rod to point A to form a reciprocating mass M c1 , and another part is converted to point B to form a rotating mass M c2 . The reciprocating mass M c1 follows the piston to make reciprocating motion, and the rotating mass M c2 rotates around point O0. Among them, the sum of M c1 and M c2 is equal to the actual mass M c of the connecting rod, and the equivalent centroid of M c1 and M c2 coincides with the actual centroid of the connecting rod. Because the shape of the connecting rod in the internal combustion engine is determined, the actual mass M c of the connecting rod and the position of the actual centroid of the connecting rod are both known, so the reciprocating mass M c1 and the rotating mass M c2 are also both known. In actual operation, M c1 and M c2 can also be weighed by two scales, and the steps are as follows: place the big end of the connecting rod on one scale, and place the small end of the connecting rod on the other scale. In this way, the big end mass weighed is M c2 , and the small end mass is M c1 .

[0040] Rotating mass M c2 The centrifugal inertial force generated by rotating about point O0 is F t = M c2 · ω 2 · r, F t is directed from point O0 to point B. In the formula, ω is the rotational speed of the crankshaft, and r is the distance between point O0 and point B. In an internal combustion engine, M c2 , ω, and r are all known quantities. Therefore, F t is known; and F r is the sum of F s and F t . Therefore, F r is known because the directions of F s and F t are both from point O0 to point B. Therefore, the direction of F r is from point O0 to point B.

[0041] Because the direction of the said F p is from point B to point O0, and F p > F r , so F p balances F r to obtain that the direction of F0 is the direction from point B to point O0, and the action line of F0 passes through point O0; among them, to make the direction of F p from point B to point O0, it only needs to make the center of mass of the balance weight on the extension line of BO0.

[0042] More specifically, because when the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively, and combined with the fact that the first balance shaft has the same rotational speed as the crankshaft and rotates in the opposite direction, and the second balance shaft has the same rotational speed as the crankshaft and rotates in the same direction, the following conclusions can be drawn:

[0043] The angle between F1 and the X direction is always equal to the angle between F0 and the X direction, and F 1x has the same direction as F 0x , F 1y has the opposite direction to F 0y ; while the direction of F2 is always the same as the direction of F0, that is, F 2x has the same direction as F 0x all the time, F 2y has the same direction as F 0y all the time; among them, F 0y is the component force of F0 in the Y direction, F 1y is the component force of F1 in the Y direction, F 2y is the component force of F2 in the Y direction, and the angle between O0B and O0A is denoted as α.

[0044] Perform a force analysis in the Y direction. Since F0 + F2 = F1, then F0·sinα + F2·sinα = F1·sinα, that is, F 0y + F 2y = F 1y , thus achieving force balance in the Y direction.

[0045] Perform a force analysis in the X direction. When F 0x + F 1x + F 2x = F j , F 0x , F 1x and F 2x balance out F j . According to the existing formula, F j = M j ·r·ω 2 ·cosα; where M j is the sum of the mass of the piston and the reciprocating mass M c1 , r is the distance between point O0 and point B, and ω is the rotational speed of the crankshaft. In an internal combustion engine, both the mass of the piston and the reciprocating mass M c1 are known quantities, so M j is known. Also, since both ω and r are known quantities, the said F j can be calculated. Among them, F 0x + F 1x + F 2x = F0·cosα + F1·cosα + F2·cosα = (F0 + F1 + F2)cosα = F j . Also, because F0 + F2 = F1, and F1·L1 = F2·L2; where both L1 and L2 are known quantities in the internal combustion engine, so the magnitudes of F0, F1, and F2 can be calculated. Then the said first balance shaft can be designed according to the magnitude of F1, the said first balance shaft can be designed according to the magnitude of F2, and F r can be obtained based on F0 and F p , and the said balance weight can be designed according to F p .

[0046] Further perform a moment analysis. The lines of action of F j and F0 both pass through point O0, so the moments of F j and F0 at point O0 are both 0. Because F1·L1 = F2·L2, the sum of the moments of F1 and F2 at point O0 (F1·cosα·L1 - F2·cosα·L2) = 0, thus achieving moment balance, and therefore no unbalanced moment will be generated. In summary, the present invention can balance the first-order reciprocating inertia force F jAnd it can achieve moment balance, avoid generating unbalanced moments, and thus can reduce the vibration of the internal combustion engine and prevent the internal combustion engine from tipping due to unbalanced moments. Description of the Drawings

[0047] Figure 1 is a schematic structural diagram of the existing double-shaft balance mechanism in the background art;

[0048] Figure 2 is an external structural schematic diagram of the new internal combustion engine balance structure of the present invention;

[0049] Figure 3 is a sectional view of the new internal combustion engine balance structure of the present invention;

[0050] Figure 4 is a schematic diagram of the internal structure of the new internal combustion engine balance structure of the present invention Figure 1 ;

[0051] Figure 5 is a schematic diagram of the internal structure of the new internal combustion engine balance structure of the present invention Figure 2 ;

[0052] Figure 6 is a schematic structural diagram of the crankshaft of the present invention;

[0053] Figure 7 is the force analysis of the new internal combustion engine balance structure of the present invention Figure 1 ;

[0054] Figure 8 is the force analysis of the new internal combustion engine balance structure of the present invention Figure 2 . Detailed Description of the Invention

[0055] In order to make the content of the present invention easier to be clearly understood, the present invention will be further described in detail below according to specific embodiments in conjunction with the drawings.

[0056] Embodiment 1: As Figures 2 to 8 shown, a new internal combustion engine balance structure, the internal combustion engine includes a housing 1, a piston 2, a connecting rod 3 and a crankshaft 4, and it includes a balance weight 5, a first balance shaft 6 and a second balance shaft 7;

[0057] The piston 2 is slidably connected in the housing 1 along the X direction;

[0058] The crankshaft 4, the first balance shaft 6 and the second balance shaft 7 are all rotatably connected to the housing 1;

[0059] The rotation center O1 of the first balance shaft 6, the rotation center O0 of the crankshaft 4 and the rotation center O2 of the second balance shaft 7 are arranged in sequence in the Y direction, and O0 is located on the extension line of the central axis of the piston 2;

[0060] The balance weight 5 is connected to the crankshaft 4;

[0061] The first balance shaft 6 is directly or indirectly drivingly connected to the crankshaft 4, and the first balance shaft 6 has the same rotational speed as the crankshaft 4 and rotates in the opposite direction;

[0062] The second balance shaft 7 is directly or indirectly drivingly connected to the crankshaft 4, and the second balance shaft 7 has the same rotational speed as the crankshaft 4 and rotates in the same direction;

[0063] One end of the connecting rod 3 is rotatably connected to the piston 2 at point A, and the other end of the connecting rod 3 is rotatably connected to the crankshaft 4 at point B, so that when the piston 2 reciprocates in the X direction, the crankshaft 4 is driven to rotate through the connecting rod 3, and then the first balance shaft 6 and the second balance shaft 7 are driven to rotate, and the following relationships are satisfied during operation:

[0064] F p is in the direction pointing from point B to point O0, and F p > F r ;

[0065] When the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively;

[0066] F0 + F2 = F1, and F1·L1 = F2·L2, and L1 < L2;

[0067] wherein, F0 is obtained by balancing F p to balance F r obtained, F p is the centrifugal inertial force generated by the rotation of the balance weight 5, F r is the sum of the centrifugal inertial force of the crankshaft 4 and the centrifugal inertial force generated by the rotating mass of the connecting rod 3, F1 is the centrifugal inertial force generated by the rotation of the first balance shaft 6, F2 is the centrifugal inertial force generated by the rotation of the second balance shaft 7, L1 is the distance in the Y direction from the rotation center O0 of the crankshaft 4 to the rotation center O1 of the first balance shaft 6, and L2 is the distance in the Y direction from the rotation center O0 of the crankshaft 4 to the rotation center O2 of the second balance shaft 7; specifically, the piston 2 reciprocates along the central axis of the piston 2, and the novel internal combustion engine balance structure can be applied to a single-cylinder diesel engine, and the specific structures of the engine housing 1, piston 2, connecting rod 3, and crankshaft 4 are all prior art.

[0068] As Figures 2 to 8 shown, the piston 2, connecting rod 3, crankshaft 4, balance weight 5, first balance shaft 6, and second balance shaft 7 are arranged to satisfy:

[0069] F0x +F 1x +F 2x =F j ; where F 0x is the component force of F0 in the X direction, F 1x is the component force of F1 in the X direction, F 2x is the component force of F2 in the X direction, F j is the sum of the first-order reciprocating inertia forces generated by the reciprocating masses of the piston 2 and the connecting rod 3. As is well known, the direction of the centrifugal inertia force is from the center of rotation to the center of mass; specifically, from the structural characteristics of the crankshaft 4, the centrifugal inertia force F s generated by the rotation of the crankshaft 4 has a direction from point O0 to point B, F s and its magnitude can be calculated according to the eccentric mass of the crankshaft 4, the eccentric radius of the crankshaft 4, and the rotational speed of the crankshaft 4 using the centrifugal force formula; among them, the eccentric mass of the crankshaft 4, the eccentric radius of the crankshaft 4, and the rotational speed of the crankshaft 4 are all known quantities, so F s is known.

[0070] When analyzing the inertia force of the connecting rod 3, it is necessary to use the mass substitution system to convert a part of the actual mass M c of the connecting rod 3 to point A to form a reciprocating mass M c1 , and another part to point B to form a rotating mass M c2 . The reciprocating mass M c1 follows the piston 2 in reciprocating motion, and the rotating mass M c2 rotates around point O0. Among them, the sum of M c1 and M c2 is equal to the actual mass M c of the connecting rod 3, and the equivalent center of mass of M c1 and M c2 coincides with the actual center of mass of the connecting rod 3. Since the shape of the connecting rod 3 in the internal combustion engine is determined, the actual mass M c of the connecting rod 3 and the position of the actual center of mass of the connecting rod 3 are both known, so the reciprocating mass M c1 and the rotating mass M c2 are also both known. In actual operation, M c1 and M c2 can also be measured by two scales, and the steps are as follows: Place the big end of the connecting rod 3 on one scale, and place the small end of the connecting rod 3 on the other scale. In this way, the big end mass measured is M c2 , and the small end mass is M c1 .

[0071] The centrifugal inertia force generated by the rotation of the rotating mass M c2 around point O0 is F t =Mc2 ·ω 2 ·r, F t is directed from point O0 to point B. In the formula, ω is the rotational speed of the crankshaft 4, and r is the distance between point O0 and point B. In an internal combustion engine M c2 , ω, and r are all known quantities. Therefore, F t is known; and F r is the sum of F s and F t . Therefore, F r is known because the directions of F s and F t are both directed from point O0 to point B. Therefore, the direction of F r is directed from point O0 to point B.

[0072] Because the direction of the said F p is from point B to point O0, and F p >F r , so F p balances F r to obtain that the direction of F0 is from point B to point O0, the action line of F0 passes through point O0, and F0 = F p -F r ; among them, to make the direction of F p from point B to point O0, it only needs to make the centroid of the balance weight 5 on the extension line of BO0.

[0073] More specifically, because when the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively. Combining that the first balance shaft 6 has the same rotational speed as the crankshaft 4 and the opposite rotation direction, and the second balance shaft 7 has the same rotational speed as the crankshaft 4 and the same rotation direction, the following conclusions can be drawn:

[0074] The angle between F1 and the X direction is always equal to the angle between F0 and the X direction, and the directions of F 1x and F 0x are the same, and the directions of F 1y and F 0y are opposite; while the direction of F2 is always the same as the direction of F0, that is, the directions of F 2x and F 0x are always the same, and the directions of F 2y and F 0y are always the same; among them, F 0y is the component force of F0 in the Y direction, F 1y is the component force of F1 in the Y direction, F 2y is the component force of F2 in the Y direction, and the angle between O0B and O0A is denoted as α.

[0075] Perform a force analysis in the Y direction. Since F0 + F2 = F1, then F0·sinα + F2·sinα = F1·sinα, that is, F 0y +F 2y =F 1y , so force balance is achieved in the Y direction.

[0076] Perform a force analysis in the X direction. When F 0x +F 1x +F 2x =F j , F 0x 、F 1x and F 2x balance out F j . According to the existing formula, F j =M j ·r·ω 2 ·cosα; where M j is the sum of the mass of piston 2 and the reciprocating mass M c1 , r is the distance between point O0 and point B, and ω is the rotational speed of the crankshaft 4. In an internal combustion engine, the mass of piston 2 and the reciprocating mass M c1 are both known quantities, so M j is known. Also, since ω and r are both known quantities, the said F j can be calculated. Among them, F 0x +F 1x +F 2x =F0·cosα + F1·cosα + F2·cosα = (F0 + F1 + F2)cosα = F j . And because F0 + F2 = F1, and F1·L1 = F2·L2; where L1 and L2 are both known quantities in the internal combustion engine, so the magnitudes of F0, F1, and F2 can be calculated. Then the first balance shaft 6 can be designed according to the magnitude of F1, the first balance shaft 6 can be designed according to the magnitude of F2, and F r can be obtained based on F0 and F p , and the balance weight 5 can be designed according to F p .

[0077] Further perform a moment analysis. The lines of action of F j and F0 both pass through point O0, so the moments of F j and F0 at point O0 are both 0. Because F1·L1 = F2·L2, the sum of the moments of F1 and F2 at point O0 (F1·cosα·L1 - F2·cosα·L2) = 0, so moment balance is achieved and no unbalanced moment will be generated. In summary, the present invention can balance the first-order reciprocating inertia force F jAnd it can achieve torque balance, avoid generating unbalanced torque, and thus can reduce the vibration of the internal combustion engine and prevent the internal combustion engine from tipping over due to unbalanced torque.

[0078] As Figures 3 to 6 shown, the crankshaft 4 may include a main journal 8, a crank arm 9, and a connecting rod journal 10. The crank arm 9 is connected to the main journal 8, the connecting rod journal 10 is connected to the crank arm 9, the main journal 8 is rotatably connected to the housing 1, the balance weight 5 is connected to the crank arm 9, and one end of the connecting rod 3 is rotatably connected to the connecting rod journal 10. Therefore, point B is at the center of the connecting rod journal 10. Specifically, the centrifugal inertia force of the crankshaft 4 is actually generated by the rotation of the crank arm 9 and the connecting rod journal 10 around point O0. Therefore, the direction of the centrifugal inertia force F s of the crankshaft 4 is from point O0 to point B. In this embodiment, the balance weight 5 includes two blocks, and the two blocks are respectively connected to the two crank arms 9.

[0079] The second balance shaft 7 may include a shaft body rotatably connected to the housing 1 and an eccentric portion 11 connected to the shaft body. The cross-sectional shape of the eccentric portion 11 is a sector. Setting the eccentric portion 11 can cause a centrifugal inertia force F2 to be generated when the second balance shaft 7 rotates. In this embodiment, the specific structure of the first balance shaft 6 is well-known prior art to those skilled in the art and will not be specifically described in this embodiment.

[0080] As Figure 4 、 5 、7, and 8 shown, the X direction is the horizontal direction, and the Y direction is the vertical direction.

[0081] The rotation center O1 of the first balance shaft 6 is directly below the rotation center O0 of the crankshaft 4.

[0082] The rotation center O2 of the second balance shaft 7 is directly above the rotation center O0 of the crankshaft 4.

[0083] As Figures 2 to 4 shown, the crankshaft 4 and the first balance shaft 6 are respectively rotatably connected within the housing 1.

[0084] The second balance shaft 7 is located outside the engine housing 1 and is rotatably connected to the upper end of the engine housing 1. Specifically, since the space inside the engine housing 1 is limited, there is not enough space to arrange the second balance shaft 7. Therefore, the second balance shaft 7 needs to be arranged outside the engine housing 1. At the same time, arranging the second balance shaft 7 outside the engine housing 1 can further save the space inside the engine housing 1, thereby enabling the engine housing 1 to be designed smaller, reducing the total weight of the internal combustion engine, and also saving the material cost of the engine housing 1. It should be clear here that arranging the second balance shaft 7 outside the engine housing 1 will cause L2 to be larger than L1.

[0085] As Figure 3 shown, the crankshaft 4 and the first balance shaft 6 can be connected by a gear pair. Specifically, the gear pair includes a driving gear 12 and a driven gear 13. The driving gear 12 is connected to the crankshaft 4, the driven gear 13 is connected to the first balance shaft 6, and the driving gear 12 and the driven gear 13 mesh with each other and have the same number of teeth, so that the first balance shaft 6 and the crankshaft 4 rotate at the same speed and in opposite directions.

[0086] As Figures 2 to 4 shown, the crankshaft 4 and the second balance shaft 7 can be connected by a transmission mechanism. The transmission mechanism can be, for example but not limited to, the following structure. It includes a driving wheel, a driven wheel 14, and a transmission belt 15. Among them,

[0087] the driving wheel is directly or indirectly connected to the crankshaft 4;

[0088] the driven wheel 14 is connected to the second balance shaft 7;

[0089] the transmission belt 15 is connected to the driving wheel and the driven wheel 14 so that when the crankshaft 4 rotates, it drives the second balance shaft 7 to rotate.

[0090] As Figure 2 、 3 shown, the new internal combustion engine balance structure can also include a flywheel 16. The flywheel 16 is connected to the crankshaft 4, and the driving wheel is connected to the flywheel 16, so that the driving wheel is indirectly connected to the crankshaft 4. Among them, the specific structure of the flywheel 16 is well-known prior art to those skilled in the art and will not be specifically described in this embodiment.

[0091] In this embodiment, the driving wheel, the driven wheel 14, and the transmission belt 15 are all located outside the engine housing 1 to further save the space inside the engine housing 1;

[0092] The driving wheel and the driven wheel 14 are both synchronous belt wheels, the transmission belt 15 is a synchronous belt, and the number of teeth on the driving wheel and the driven wheel 14 is equal; specifically, the equal number of teeth on the driving wheel and the driven wheel 14 enables the second balance shaft 7 to have the same rotational speed and the same direction of rotation as the crankshaft 4.

[0093] More specifically, since the rotation directions of the crankshaft 4 and the second balance shaft 7 are the same, if a gear drive is used between the crankshaft 4 and the second balance shaft 7, at least 3 gears are required, which will occupy a large space and increase the cost, and make the structure more complex. Therefore, using a synchronous belt drive or a chain drive can reduce the cost and save space.

[0094] Analyzing from another perspective, because F0 + F2 = F1, and F1·L1 = F2·L2, it can be deduced that F0·L1 = F2·(L2 - L1). Therefore, F0 and F2 can be equivalent to a force F3, and the direction of F3 is the same as that of F0; the magnitude of F3 is the sum of F0 and F2, that is, F3 = F0 + F2 = F1. Let the acting point of F3 be O3, point O3 is between point O0 and point O2, and the distance between point O3 and O0 is L1. Therefore, the combined action of F1 and F3 can cancel out the first-order reciprocating inertia force F j , and no unbalanced torque will be generated.

[0095] Embodiment 2: An internal combustion engine, which includes the novel internal combustion engine balance structure as described in Embodiment 1; specifically, the internal combustion engine can be, but is not limited to, a single-cylinder diesel engine.

[0096] The working principle of the present invention is as follows:

[0097] The direction of the centrifugal inertia force is from the center of rotation to the center of mass. From the structural characteristics of the crankshaft 4, it can be known that the centrifugal inertia force F s generated by the rotation of the crankshaft 4 is in the direction from point O0 to point B, and F s The magnitude of can be calculated according to the eccentric mass of the crankshaft 4, the eccentric radius of the crankshaft 4, and the rotational speed of the crankshaft 4 by using the centrifugal force formula; among them, the eccentric mass of the crankshaft 4, the eccentric radius of the crankshaft 4, and the rotational speed of the crankshaft 4 are all known quantities, so F s is known.

[0098] When analyzing the inertia force of the connecting rod 3, it is necessary to use the mass substitution system to transfer a part of the actual mass M c of the connecting rod 3 to point A to form a reciprocating mass M c1 , and another part is transferred to point B to form a rotating mass M c2 . The reciprocating mass M c1 follows the piston 2 to make a reciprocating motion, and the rotating mass M c2Make a rotational motion about point O0. Among them, M c1 and M c2 The sum is equal to the actual mass M of the connecting rod 3 c , M c1 and M c2 The equivalent center of mass coincides with the actual center of mass of the connecting rod 3. Since the shape of the connecting rod 3 in the internal combustion engine is determined, the actual mass M of the connecting rod 3 c and the position of the actual center of mass of the connecting rod 3 are both known. Therefore, the reciprocating mass M c1 and the rotating mass M c2 are also both known. In actual operation, M c1 and M c2 can also be measured by two scales as follows: Place the big end of the connecting rod 3 on one scale and the small end of the connecting rod 3 on the other scale. The mass of the big end thus measured is M c2 , and the mass of the small end is M c1 .

[0099] The centrifugal inertial force generated by the rotation of the rotating mass M c2 about point O0 is F t =M c2 ·ω 2 ·r, and the direction of F t is from point O0 to point B. In the formula, ω is the rotational speed of the crankshaft 4, and r is the distance between point O0 and point B. In the internal combustion engine, M c2 , ω, and r are all known quantities. Therefore, F t is known; and F r is the sum of F s and F t . Therefore, F r is known. Since the directions of F s and F t are both from point O0 to point B, the direction of F r is from point O0 to point B.

[0100] Since the direction of the said F p is from point B to point O0, and F p >F r , so F p balances F r to obtain that the direction of F0 is from point B to point O0, and the action line of F0 passes through point O0; among them, to make the direction of F p from point B to point O0, it only needs to make the center of mass of the balance weight 5 on the extension line of BO0.

[0101] More specifically, since when the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively, and considering that the rotational speed of the first balance shaft 6 is equal to that of the crankshaft 4 and the rotation directions are opposite, and the rotational speed of the second balance shaft 7 is equal to that of the crankshaft 4 and the rotation directions are the same, the following conclusions can be drawn:

[0102] The angle between F1 and the X direction is always equal to the angle between F0 and the X direction, and F 1x has the same direction as F 0x , and F 1y has the opposite direction to F 0y ; while the direction of F2 is always the same as the direction of F0, that is, F 2x has the same direction as F 0x all the time, and F 2y has the same direction as F 0y all the time; where F 0y is the component force of F0 in the Y direction, F 1y is the component force of F1 in the Y direction, F 2y is the component force of F2 in the Y direction, and the angle between O0B and O0A is denoted as α.

[0103] Conduct a force analysis in the Y direction. Since F0 + F2 = F1, then F0·sinα + F2·sinα = F1·sinα, that is, F 0y + F 2y = F 1y , so force balance is achieved in the Y direction.

[0104] Conduct a force analysis in the X direction. When F 0x + F 1x + F 2x = F j , F 0x , F 1x and F 2x balance out F j . According to the existing formula, F j = M j ·r·ω 2 ·cosα; where M j is the sum of the mass of the piston 2 and the reciprocating mass M c1 , r is the distance between point O0 and point B, and ω is the rotational speed of the crankshaft 4. In an internal combustion engine, the mass of the piston 2 and the reciprocating mass M c1 are both known quantities, so M j is known. Also, since ω and r are both known quantities, the said F j can be calculated. Among them, F 0x + F 1x + F 2x= F0·cosα + F1·cosα + F2·cosα = (F0 + F1 + F2)cosα = F j Moreover, since F0 + F2 = F1, and F1·L1 = F2·L2; where L1 and L2 are both known quantities in the internal combustion engine, the magnitudes of F0, F1, and F2 can thus be calculated. Then, the first balance shaft 6 can be designed according to the magnitude of F1, the first balance shaft 6 can be designed according to the magnitude of F2, and according to F0 and F r F can be obtained p According to F p the balance weight 5 can be designed.

[0105] By further performing moment analysis, the action lines of F j and F0 both pass through point O0. Therefore, the moments of F j and F0 at point O0 are both 0. Since F1·L1 = F2·L2, the sum of the moments of F1 and F2 at point O0 (F1·cosα·L1 - F2·cosα·L2) = 0. Therefore, moment balance is achieved, and thus no unbalanced moment will be generated. In summary, the present invention can balance the first-order reciprocating inertia force F j under the condition of L1 < L2 and can achieve moment balance, avoiding the generation of unbalanced moments, thereby being able to reduce the vibration of the internal combustion engine and prevent the internal combustion engine from tipping over due to unbalanced moments.

[0106] In the specific embodiments described above, the technical problems solved, the technical solutions, and the beneficial effects of the present invention are further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An internal combustion engine balance structure, the internal combustion engine comprising a housing (1), a piston (2), a connecting rod (3) and a crankshaft (4), characterized in that, It includes a balance weight (5), a first balance shaft (6) and a second balance shaft (7); The piston (2) is slidably connected in the housing (1) along the X direction; The crankshaft (4), the first balance shaft (6) and the second balance shaft (7) are all rotatably connected to the housing (1); The rotation center O1 of the first balance shaft (6), the rotation center O0 of the crankshaft (4) and the rotation center O2 of the second balance shaft (7) are arranged in sequence in the Y direction, and O0 is located on the extension line of the central axis of the piston (2); The balance weight (5) is connected to the crankshaft (4); The first balance shaft (6) is directly or indirectly drivingly connected to the crankshaft (4), and the first balance shaft (6) has the same rotational speed as the crankshaft (4) and rotates in the opposite direction; The second balance shaft (7) is directly or indirectly drivingly connected to the crankshaft (4), and the second balance shaft (7) has the same rotational speed as the crankshaft (4) and rotates in the same direction; One end of the connecting rod (3) is rotatably connected to the piston (2) at point A, and the other end of the connecting rod (3) is rotatably connected to the crankshaft (4) at point B, so that when the piston (2) reciprocates along the X direction, the crankshaft (4) is driven to rotate through the connecting rod (3), and the following relationship is satisfied during operation: F p The direction of F points from point B to point O0, and F p > F r ; When the direction of F0 is parallel to the X direction, the directions of F1 and F2 are the same as the direction of F0 respectively; F0 + F2 = F1, and F1·L1 = F2·L2, and L1 < L2; Among them, F0 is balanced by F p to obtain F r where F p is the centrifugal inertial force generated by the rotation of the balance weight (5), F r is the sum of the centrifugal inertial force of the crankshaft (4) and the centrifugal inertial force generated by the rotating mass of the connecting rod (3), F1 is the centrifugal inertial force generated by the rotation of the first balance shaft (6), F2 is the centrifugal inertial force generated by the rotation of the second balance shaft (7), L1 is the distance in the Y direction from the rotation center O0 of the crankshaft (4) to the rotation center O1 of the first balance shaft (6), and L2 is the distance in the Y direction from the rotation center O0 of the crankshaft (4) to the rotation center O2 of the second balance shaft (7); Wherein, the piston (2), the connecting rod (3), the crankshaft (4), the balance weight (5), the first balance shaft (6) and the second balance shaft (7) are arranged to satisfy: F 0x + F 1x + F 2x = F j ; where F 0x is the component force of F0 in the X direction, F 1x is the component force of F1 in the X direction, F 2x is the component force of F2 in the X direction, F j is the sum of the first-order reciprocating inertia forces generated by the reciprocating masses of the piston (2) and the connecting rod (3); Wherein, the crankshaft (4) includes a main journal (8), a crank arm (9) and a connecting rod journal (10), the crank arm (9) is connected to the main journal (8), the connecting rod journal (10) is connected to the crank arm (9), the main journal (8) is rotatably connected to the housing (1), the balance weight (5) is connected to the crank arm (9), and one end of the connecting rod (3) is rotatably connected to the connecting rod journal (10); The second balance shaft (7) includes a shaft body rotatably connected to the housing (1) and an eccentric portion (11) connected to the shaft body.

2. The internal combustion engine balance structure according to claim 1, characterized in that The X direction is the horizontal direction, and the Y direction is the vertical direction; The rotation center O1 of the first balance shaft (6) is located directly below the rotation center O0 of the crankshaft (4); The rotation center O2 of the second balance shaft (7) is located directly above the rotation center O0 of the crankshaft (4).

3. The internal combustion engine balance structure according to claim 1, characterized in that The crankshaft (4) and the first balance shaft (6) are respectively rotatably connected inside the housing (1); The second balance shaft (7) is located outside the housing (1) and is rotatably connected to the upper end of the housing (1).

4. The internal combustion engine balance structure according to claim 1, characterized in that, The crankshaft (4) and the first balance shaft (6) are drivingly connected through a gear pair.

5. The internal combustion engine balance structure according to claim 1, characterized in that, The crankshaft (4) is connected to the second balance shaft (7) through a transmission mechanism, and the transmission mechanism includes a driving wheel, a driven wheel (14) and a transmission belt (15); wherein, The driving wheel is directly or indirectly connected to the crankshaft (4); The driven wheel (14) is connected to the second balance shaft (7); The transmission belt (15) is connected to the driving wheel and the driven wheel (14) so that when the crankshaft (4) rotates, the second balance shaft (7) is driven to rotate.

6. The internal combustion engine balance structure according to claim 5, characterized in that, It further includes a flywheel (16), the flywheel (16) is connected to the crankshaft (4), and the driving wheel is connected to the flywheel (16).

7. The internal combustion engine balance structure according to claim 5, characterized in that, The driving wheel, the driven wheel (14) and the transmission belt (15) are all located outside the engine housing (1); The driving wheel and the driven wheel (14) are both synchronous belt wheels, the transmission belt (15) is a synchronous belt, and the number of teeth on the driving wheel and the driven wheel (14) is equal.

8. An internal combustion engine, characterized in that, It includes the internal combustion engine balance structure according to any one of claims 1 to 7.

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