1. An oil pan structure of an engine for a vehicle, comprising
an oil pan attached to a lower portion of the engine having plural cylinders, wherein
the oil pan has an approximately rectangular bottom wall which accumulates oil continually and extends in a direction of each cylinder line as viewed from an upper side, a long side wall extending parallel to the cylinder line, and a short side wall extending perpendicular to the cylinder line, the approximately rectangular bottom wall being surrounded by the long side wall and the short side wall,
the bottom wall has a flat deep bottom section provided approximately in a center of the bottom wall and in a portion where the oil is pumped up, a shallow bottom section which has a depth that is shallower than that of the deep bottom section, and a connecting wall section extending vertically and connecting the deep bottom section with the shallow bottom section,
the shallow bottom section is provided on both sides of the deep bottom section,
the bottom wall includes two flat L shaped regions which are located at respective diagonal positions across the deep bottom section, the L shaped regions each demarcated by the connecting wall section and respectively comprising first deep bottom extending sections extending in opposite directions away from the deep bottom section parallel to an engine longitudinal direction and respective second deep bottom extending sections extending from a distal end of the first deep bottom extending sections in opposite directions that are each perpendicular to the corresponding first deep bottom extending sections, and
the connecting wall section connects the deep bottom section, the first deep bottom extending sections and the second deep bottom extending sections with the shallow bottom section, and extends in an approximately L shape as viewed from the upper side.
2. The oil pan structure according to claim 1 wherein
the short side wall and the bottom wall are connected to each other via a step wall section protruding inward of the oil pan.
3. The oil pan structure according to claim 1 further comprising,
a protrusion provided on one side in a direction parallel to the cylinder line as viewed from the upper side, a depth of the protrusion being shallower than that of the shallow bottom section.
4. The oil pan structure according to claim 1 wherein
the bottom wall, the long side wall and the short side wall are formed by casting light alloy.
5. The oil pan structure according to claim 1 wherein
the shallow bottom section includes regions that are provided on both sides of the deep bottom section in directions parallel to the cylinder line as viewed from the upper side.
6. The oil pan structure according to claim 5 wherein
the short side wall and the bottom wall are connected to each other via a step wall section protruding inward of the oil pan.
7. The oil pan structure according to claim 5 wherein
the bottom wall, the long side wall and the short side wall are formed by casting light alloy.
8. The oil pan structure according to claim 1 wherein
the bottom wall has deep bottom extending sections, including the first and second deep bottom extending sections, which extend respectively from the deep bottom section in four directions parallel to or perpendicular to the cylinder line as viewed from the upper side, and
the shallow bottom section is positioned outside of each deep bottom extending section.
9. The oil pan structure according to claim 8 wherein
the short side wall and the bottom wall are connected to each other via a step wall section protruding inward of the oil pan.
10. The oil pan structure according to claim 8 wherein
the bottom wall, the long side wall and the short side wall are formed by casting light alloy.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A mud motor for use in a wellbore, the mud motor comprising:
a rotor, the rotor including at least one generally helical rotor lobe extending therefrom;
a stator, the stator being generally tubular in shape and including at least two generally helical stator lobes extending inward from an inner surface thereof, the at least two generally helical stator lobes adapted to interface with the at least one generally helical rotor lobe to create at least one cavity between the stator and the rotor such that the cavity traverses the length of the stator as the rotor eccentrically rotates within the stator, the distance between the stator and the rotor at a given point along the mud motor defining a tolerance, the tolerance at a first point along the mud motor being larger than the tolerance at a second point along the mud motor.
2. The mud motor of claim 1, wherein the rotor comprises a first major rotor diameter and a first minor rotor diameter at a first point along the rotor corresponding with the first point along the mud motor and a second major rotor diameter and a second minor rotor diameter at a second point along the rotor corresponding with the second point along the mud motor, and at least one of the first major rotor diameter and the first minor rotor diameter is smaller than the second major rotor diameter and the second minor rotor diameter respectively.
3. The mud motor of claim 1, wherein the stator comprises a first major stator diameter and a first minor stator diameter at a first point along the stator corresponding with the first point along the mud motor and a second major stator diameter and a second minor stator diameter at a second point along the stator corresponding with the second point along the mud motor, and at least one of the first major stator diameter and the first minor stator diameter is larger than the second major stator diameter and the second minor stator diameter respectively.
4. The mud motor of claim 1, wherein the stator comprises an outer cover and a stator insert, the outer cover being generally tubular, and the stator insert being formed within the outer cover and including the at least two generally helical stator lobes.
5. The mud motor of claim 1, wherein the first point along the mud motor is positioned nearer the lower end of the mud motor than the second point along the mud motor.
6. The mud motor of claim 1, wherein the first point along the mud motor is positioned nearer the upper end of the mud motor than the second point along the mud motor.
7. The mud motor of claim 1, further comprising a third point along the mud motor, the tolerance at the third point along the mud motor being larger than the tolerance at the second point along the mud motor.
8. The mud motor of claim 7, wherein the second point along the mud motor is positioned between the first point along the mud motor and the third point along the mud motor.
9. The mud motor of claim 1, further comprising a third point along the mud motor, the tolerance at the third point along the mud motor being tighter than the tolerance at the first point along the mud motor.
10. The mud motor of claim 9, wherein the first point along the mud motor is positioned between the second point along the mud motor and the third point along the mud motor.
11. A stator for a mud motor for use in a wellbore comprising:
an outer cover, the outer cover being generally tubular; and
a stator insert, the stator insert being generally tubular in shape and including at least two generally helical stator lobes extending inward from an inner surface of the outer cover, the at least two generally helical stator lobes adapted to interface with at least one generally helical rotor lobe of a rotor to create at least one cavity between the stator and the rotor such that the cavity traverses the length of the stator as the rotor eccentrically rotates within the stator, the at least two stator lobes defining a first major stator diameter and a first minor stator diameter at a first point along the stator and a second major stator diameter and a second minor stator diameter at a second point along the stator, and at least one of the first major stator diameter and the first minor stator diameter is larger than the second major stator diameter and the second minor stator diameter respectively.
12. A method of forming a stator for use in a mud motor comprising:
providing an outer cover, the outer cover being generally tubular;
providing a mold core, the mold core including an outer profile, the outer profile being the negative of a stator inner profile, the stator inner profile including at least two generally helical stator lobes extending inward from an inner surface of the outer cover, the at least two generally helical stator lobes adapted to interface with at least one generally helical rotor lobe of a rotor to create at least one cavity between the stator and the rotor such that the cavity traverses the length of the stator as the rotor eccentrically rotates within the stator, the at least two stator lobes defining a first major stator diameter and a first minor stator diameter at a first point along the stator and a second major stator diameter and a second minor stator diameter at a second point along the stator, and at least one of the first major stator diameter and the first minor stator diameter is larger than the second major stator diameter and the second minor stator diameter respectively;
positioning the mold core within the outer cover;
injecting an elastomer between the outer cover and the mold core, the elastomer adapted to couple to the inner surface of the outer cover and retain the stator inner profile;
hardening the elastomer; and
removing the mold core from the outer cover.
13. A method of forming a stator for use in a mud motor comprising:
providing an outer cover, the outer cover being generally tubular; and
forming, in the outer cover, a stator inner profile, the stator inner profile including at least two generally helical stator lobes extending inward, the at least two generally helical stator lobes adapted to interface with at least one generally helical rotor lobe of a rotor to create at least one cavity between the stator and the rotor such that the cavity traverses the length of the stator as the rotor eccentrically rotates within the stator, the at least two stator lobes defining a first major stator diameter and a first minor stator diameter at a first point along the stator and a second major stator diameter and a second minor stator diameter at a second point along the stator, and at least one of the first major stator diameter and the first minor stator diameter is larger than the second major stator diameter and the second minor stator diameter respectively.
14. A method of assembling a mud motor comprising:
providing a mud motor stator;
providing a rotor, the rotor including at least one generally helical rotor lobe extending therefrom, the rotor having a first major rotor diameter and a first minor rotor diameter at a first point along the rotor and a second major rotor diameter and a second minor rotor diameter at a second point along the rotor, at least one of the first major rotor diameter and the first minor rotor diameter being smaller than the second major rotor diameter and the second minor rotor diameter respectively; and
positioning the rotor within the stator.