CN202338560U - Automobile engine crankshaft - Google Patents

Abstract

The utility model relates to an automobile engine crankshaft which comprises four unit cranks, a balancing weight, a front crankshaft end and a rear crankshaft end, wherein the four unit cranks are sequentially connected; the front crankshaft end and the rear crankshaft end are arranged at the two ends of the crankshaft and connected with the unit cranks; each unit crank is composed of a crank pin, two crank arms and two main journals, the two crank arms are arranged on the left and right sides of the crank pin, and the two main journals are arranged on the outer sides of the two crank arms; and the outer sides of one ends (close to the crank pin) of the crank arms are respectively provided with a concave arc scanning-form weight reduction part. According to the utility model, under the condition of not changing the structure of a crankcase and the design on other peripheral parts, through carrying out weight reduction on the crank arms and carrying out weight increase on the balancing weight as far as possible, the balance rate of an engine crankshaft is effectively improved, thereby realizing the concurrent consideration of strength, rigidity, friction, vibration and cost of the crankshaft better.

Description

car engine crankshaft

technical field

The utility model relates to an automobile engine, in particular to an automobile engine crankshaft. the

Background technique

In the prior art, automobile engine crankshafts are basically made of forged steel or cast iron. the

The forged steel crankshaft is processed by forging process, and then the carbon steel or alloy steel is quenched and tempered to obtain high strength and rigidity. In recent years, in order to improve machinability and reduce processing and production costs, lead-free, non-quenched and tempered steels that are easy to machinable have also been widely used. the

In order to reduce the vibration when the engine is running to obtain a good NVH (Noise-noise; Vibration-vibration; Harshness-sound-vibration roughness) effect, mid-level displacement engines generally adopt a full-balanced crankshaft design to achieve a high balance rate. The forged steel crankshaft in the form of full balance weight can obtain high strength and rigidity and good NVH effect, but it has the disadvantages of large weight, large friction loss, and high cost. the

The cast iron crankshaft is generally made of ductile iron and processed by casting process. This kind of crankshaft has low density, light weight and high elasticity, which is very beneficial to the NVH effect, and can use the lubricity of graphite precipitated on the crankshaft journal when the engine is running to reduce friction loss. However, for mid-level displacement engines with high power and high torque, the rigidity and strength of such crankshafts are difficult to meet the requirements. For ductile iron crankshafts to be applied to mid-level displacement engines, especially turbocharged engines, the strength and stiffness must first meet the design requirements, which is often at the expense of the overall balance of the crankshaft and NVH. the

Utility model content

The technical problem to be solved by the utility model is to provide an automobile engine crankshaft, which further improves the balance rate of the crankshaft under the premise of ensuring the strength and stiffness of the crankshaft, and reduces the vibration and vibration caused by the crankshaft itself when the engine is running. noise. the

In order to solve the above-mentioned technical problems, the crankshaft of the automobile engine of the utility model includes: four unit crank throws connected in sequence, wherein each unit crank throw includes a crank pin, two crank arms located on the left and right sides of the crank pin, and two crank arms located on the left and right sides of the crank pin. Two main journals on the outside of the arm; a counterweight mounted on each crank arm, the counterweight is in the shape of a sector; and a crankshaft front end and a crankshaft rear end connected to the crankshaft at both ends of the crankshaft; wherein, the The crank arm is provided with a weight-reducing part in the form of a concave arc sweep at the outer side of the end close to the crank pin; the radius of the two balance weights near the front end of the crankshaft and the two balance weights near the rear end of the crankshaft is 72.3-72.7mm, The radius of the four balance weights in the middle is 71.8-72.2mm; the thickness of one balance weight near the rear end of the crankshaft is 13.1-13.5mm, and the thickness of the remaining balance weights is 14.3-14.7mm. the

The utility model reduces the weight of the crank arm through the form of concave arc sweep on the crank arm of the crankshaft. Compared with the weight reduction in the form of oblique section in the prior art, the weight reduction of the form of concave arc sweep can reduce more crank arms weight. In addition, compared with the radius and thickness of the balance weight in the prior art, the thickness and radius of the balance weight of the automobile engine crankshaft of the utility model are all increased. The heavier ones weigh more. the

Without changing the structure of the crankcase and the design of other peripheral parts, the utility model effectively improves the balance rate of the crankshaft of the engine by reducing the weight of the crank arm and increasing the weight of the balance weight as much as possible, and better realizes the crankshaft itself. Balance of strength, rigidity, friction, vibration and cost. the

According to an embodiment of the present utility model, the radius of the two balance weights near the front end of the crankshaft and the two balance weights near the rear end of the crankshaft is 72.5mm, and the radius of the four balance weights in the middle is 72mm. The thickness of one balance weight near the rear end of the crankshaft is 13.3mm, and the thickness of the remaining balance weights is 14.5mm. the

Experiments show that the above-mentioned design parameters can increase the balance rate of the engine crankshaft to 76.5%, which is about 20% higher than that of the engine crankshaft in the prior art. the

Description of drawings

Fig. 1 is the plane view of the utility model automobile engine crankshaft;

FIG. 2 is a perspective view of the crank arm shown in FIG. 1 . the

Detailed ways

Below in conjunction with accompanying drawing and specific embodiment, the crankshaft of automobile engine of the utility model is described in further detail. the

Fig. 1 is the plane view of the utility model automobile engine crankshaft. As shown in the figure, the crankshaft of the automobile engine of the utility model includes a crankshaft front end 11, unit crank throws 12-15 (represented by dotted lines) and a crankshaft rear end 17 connected in sequence. Each unit crank includes a crank pin 21 , two crank arms 23 located on the left and right sides of the crank pin 21 , and two main journals 26 located outside the two crank arms 23 . the

The front end 11 of the crankshaft and the rear end 17 of the crankshaft are respectively connected with the unit crank throws 12 and 15 . More precisely, the crankshaft front end 11 and the crankshaft rear end 17 are fixedly connected to the main journals 26 of the unit crank throw 12 and the unit crank throw 15 respectively. the

Strictly speaking, the number of main journals 26 in the figure is not enough to make each unit crank throw include two main journals, but for the convenience of description, the unit crank throws 12-15 are described in the above manner. Therefore, as can be seen from the figure, two adjacent unit crank throws share a main journal 26, or in other words, adjacent unit crank throws are fixedly connected through a common main journal 26, and the main journal 26 as a connecting part can be used as The main journal of a unit crank throw can also be used as the main journal of another adjacent unit crank throw. the

In this embodiment, the crank pin 21 of the unit crank throw 12 near the front section 11 of the crankshaft and the crank throw 15 of the unit crank throw 15 near the rear end 17 of the crankshaft are located on one side of the crankshaft center line Y, and the crank pins of the two unit crank throws 13 and 14 in the middle are The pin 21 is located on the other side of the crankshaft centerline Y. the

As shown in Fig. 1, a balance weight 31-38 is installed on each crank arm, and the shape of the balance weight 31-38 is fan-shaped. The radius of the two balance weights 31 and 32 near the front end of the crankshaft and the two balance weights 37 and 38 near the rear end of the crankshaft is 72.3-72.7mm, and the radius of the four balance weights 33-36 in the middle is 71.8-72.2mm. In this embodiment, the radii of the counterweights 31, 32, 37 and 38 are preferably 72.5mm, and the radii of the middle four counterweights 33-36 are preferably 72mm. The radii of the counterweights 31, 32, 37 and 38 are 0.5mm larger than the radii of the counterweights 33-36, which optimizes the overall static balance of the crankshaft itself. the

The thickness of the balance weight 38 is 13.1-13.5mm, and the thickness of the remaining balance weights 31-37 is 14.3-14.7mm. In this embodiment, the thickness of the balance weight 38 is preferably 13.3 mm. Preferably, under the premise of not affecting the machining of the main journal 26 and the crank pin 21, the thickness of the balance weights 31-37 is increased to 14.5mm. the

Compared with the balance weight of an engine crankshaft whose radius is 69mm and thickness is 13.8mm in the prior art, the thickness and radius of the balance weight of the automobile engine crankshaft of the utility model are all increased. The counterweight of the new car engine crankshaft has a greater weight. At the same time, the increase of the radius of the balance weight can change the distance of the center of mass of the balance weight relative to the center line Y of the crankshaft, which is also conducive to improving the balance ratio of the crankshaft. the

As shown in FIG. 2 , the crank arm 23 is provided with a lightening portion 28 in the form of a concave arc sweep at the outer side of the end close to the crank pin 21 . Compared with the weight reduction in the form of oblique cutting planes in the prior art, the weight reduction in the form of concave arc sweeping can reduce more weight, thereby helping to improve the balance ratio of the crankshaft. In this embodiment, weight reduction in the form of a concave arc sweep cuts about 5% of the crank arm weight. the

Experiments have shown that the balance ratio of the engine crankshaft can be increased to 76.5% by adopting the above-mentioned design parameters of the counterweight in this embodiment and that the weight reduction part of the crank arm accounts for about 5% of the weight of the crank arm. The crankshaft (the radius of the balance weight is 69mm, the thickness is 13.8mm, and the weight reduction part is an oblique cut surface), the balance ratio of the crankshaft has increased by about 20%. the

The crankshaft of the automobile engine of the utility model can increase the weight of the balance weight and change the balance by increasing the radius and thickness of the balance weight without affecting the movement interference between the balance weight and the surrounding parts such as the cylinder body assembly, the oil pan assembly, and the piston. Heavy center of mass position, thereby improving the crankshaft balance ratio. At the same time, under the premise of ensuring the strength of the crank arm, the weight reduction in the form of concave arc sweep is adopted to reduce the weight of the crank arm part to the greatest extent so as to improve the balance ratio of the crankshaft. The improvement of the balance ratio of the crankshaft is beneficial to reduce the vibration and noise caused by the crankshaft itself when the engine is running, and better realize the balance of the strength, rigidity, friction, vibration and cost of the crankshaft itself. the

The crankshaft of the automobile engine of the utility model can be shared by a naturally aspirated inline four-cylinder gasoline engine and an exhaust gas turbocharged engine with the same displacement. the

The utility model is not limited to the above-mentioned specific embodiments, and the technical solutions that are obvious to those skilled in the art can make various changes and/or modifications to the utility model without departing from the spirit or scope of the utility model. It belongs to the protection scope of the utility model. the

Claims (5)

1. An automobile engine crankshaft, comprising: Four sequentially connected unit crank throws, wherein each unit crank throw is composed of a crank pin, two crank arms on the left and right sides of the crank pin, and two main journals on the outside of the two crank arms; a counterweight mounted on each of said crank arms, said counterweight being sector-shaped; and The front end of the crankshaft and the rear end of the crankshaft, which are located at both ends of the crankshaft and connected to the crank throw of the unit; It is characterized in that, The crank arm is provided with a weight-reducing portion in the form of a concave arc sweep at the outer side of one end close to the crank pin; The radius of the two balance weights near the front end of the crankshaft and the two balance weights near the rear end of the crankshaft is 72.3-72.7mm, and the radius of the four balance weights in the middle is 71.8-72.2mm; The thickness of one balance weight near the rear end of the crankshaft is 13.1-13.5mm, and the thickness of the remaining balance weights is 14.3-14.7mm. 2. The automobile engine crankshaft according to claim 1, wherein the radius of the two counterweights near the front end of the crankshaft and the two counterweights near the rear end of the crankshaft is 0.5 larger than the radius of the middle four counterweights. mm. 3. The automobile engine crankshaft according to claim 2, wherein the radius of the two balance weights near the front end of the crankshaft and the two balance weights near the rear end of the crankshaft is 72.5mm, and the radius of the four balance weights in the middle is 72.5 mm. The radius is 72mm. 4. The automobile engine crankshaft according to claim 1 or 3, wherein the thickness of a balance weight near the rear end of the crankshaft is 13.3mm, and the thickness of the remaining balance weights is 14.5mm. 5. The automobile engine crankshaft according to claim 1, wherein the crankpins of the unit crank throw near the front end of the crankshaft and the crank pins of the unit crank throw near the rear end of the crankshaft are located on one side of the crankshaft center line, and the two in the middle are The crankpin of the unit crank throw is on the opposite side of the crankshaft centerline.

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