JP2507349Y2 - Ski propeller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a squeeze propeller for a ship.

[Conventional technology]

In the conventional squeeze propeller, as shown in the front view of FIG. 3 and the side view of FIG. 4, 1 is a propeller.
Wings, 2 are propeller bosses, 3 are leading edges of propeller wings, 4
Is the trailing edge of the propeller blade, 5 is the back surface of the propeller blade,
Reference numeral 6 indicates the facet of the propeller blade, 7 indicates the point where stress concentration occurs, T indicates the thrust acting on the propeller blade, and F indicates the centrifugal force acting on the blade tip.

[Problems to be solved by the device]

In this type of propeller, as shown in FIG. 3, when the skew angle is 25 degrees or more, the blade trailing edge 4 becomes concave, and the thrust T acting on the propeller blade 1 causes the trailing edge of the 0.4 to 0.6 radial position. Stress concentration is likely to occur on the face surface of.

For this reason, in a normal skied propeller, the entire propeller blade 1 is inclined forward, that is, a forward rake is often adopted. By adding a rake to the front, the bending moment F × due to the centrifugal force F at the blade tip
With respect to the stress concentration point 7, d is opposite to the bending moment due to the thrust T, and the stress concentration is relaxed.

[Problems to be solved by the invention] However, in conventional squeeze propellers, it is common to have a constant rake angle in the radial direction. Since corners cannot be used, stress concentration tends to occur on the trailing edge face surface at the 0.4 to 0.6 radius position.

Therefore, in order to prevent this, conventionally, the blade thickness at the 0.4 to 0.6 radius position is locally increased, or the blade thickness at the trailing edge is increased, but for that reason, the propeller weight is increased. However, the propeller efficiency will decrease.

The present invention has been proposed in view of such circumstances,
The purpose is to provide a lightweight and highly efficient economical squid propeller.

[Means for solving the problem]

Therefore, in the present invention, in the skewed propeller, all the propeller blades are raked backward on the blade root side of the propeller blades, raked forward on the tip side, and the skew line is winged on the blade root side. The feature is that it is oriented toward the leading edge and toward the trailing edge of the blade on the tip side.

[Action]

According to such a configuration, since the rake angle is set to the front side at the radial position outside the blade, the distance d from the action point of the centrifugal force F to the stress concentration point 7 becomes large, and the bending due to the thrust T occurs. Bending moment in the direction opposite to the moment increases, and stress concentration can be prevented.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial front view thereof, and FIG. 2 is a side view of FIG.

In the above figure, the same reference numerals as in FIGS. 3 to 4 indicate the same members as in the figures, and the line connecting the midpoints of the leading edge 3 and the trailing edge 4 in the radial direction is called the skew line. The difference between the maximum value and the minimum value of the angle formed by the straight line connecting the skew line and the propeller axis with the propeller bus is called the skew angle. When the skew angle exceeds a certain value (25 degrees or more), the trailing edge 4 of the propeller blade 1 has a concave shape.

FIG. 2 is a side view of the propeller, in which the radial distribution of the maximum radial thickness in the front-rear direction (rake) is also shown. For propellers with a skew angle of 25 degrees or more,
Up to the radial position 7 (usually 0.4 to 0.6 radial position) where the trailing edge 4 of the propeller blade 1 is the most concave, the rake is taken rearward, and at the further radial positions, the rake is taken forward conversely. That is, the inflection point of the rear rake and the front rake is 0.4 ~
Located at 0.7 radius. Moreover, the front rake angle is 10
It is more than ° and secures a large front rake.

[Effect of device]

In the skied propeller, the propeller thrust T causes
Stress concentration may occur on the face surface side of the most concavely curved portion of the trailing edge 4 of the propeller blade 1, resulting in excessive tensile stress. With the propeller of the present invention, stress concentration is likely to occur. The propeller blade 1 is largely inclined forward at a radial position outside the 0.6 radial position.

Therefore, due to the centrifugal force F generated at the blade tip, a bending moment (F × d) opposite to the bending moment due to the thrust T acts on the stress concentration point 7, and the magnitude of the tensile stress at this position. Is greatly reduced. as a result,
It is not necessary to increase the blade thickness or the trailing edge thickness at this radial position, and it is possible to prevent an increase in weight and a decrease in efficiency.

The present invention can be applied not only to marine propellers, but also to aircraft propellers, fans, fans, and the like.

In short, according to the present invention, in a skewed propeller, all propeller blades are raked rearward on the blade root side of the propeller blades, raked forward on the tip side, and skew lines on the blade root side. The present invention is extremely useful in the industry because it has a light weight and high efficiency economical squid propeller by orienting toward the leading edge of the blade and facing toward the trailing edge of the blade on the tip side. is there.

[Brief description of drawings]

FIG. 1 is a partial front view showing an embodiment of the present invention, and FIG. 2 is a side view of FIG. FIG. 3 is a partial front view of a known skied propeller, and FIG. 4 is a side view of FIG. 1 ... Propeller blade, 2 ... Propeller boss, 3 ... Propeller blade leading edge, 4 ... Propeller blade trailing edge, 5 ... Propeller blade back surface, 6 ... Propeller blade face surface, 7
...... Stress concentration points,

Claims (1)

(57) [Scope of utility model registration request] 1. In a skewed propeller, all propeller blades are raked rearward on the blade root side of the propeller blades, raked forward on the tip side, and skew lines are forwardly winged on the blade root side. Take the edge direction,
On the tip side, the skewed propeller is characterized by facing the trailing edge of the blade.