Plate spring unit and railcar bogie

1. A plate spring unit configured to be applied to a railcar bogie, the plate spring unit comprising:

a lower plate spring including an end portion along a longitudinal direction, the end portion being configured to be supported by an axle box of the railcar bogie at a lower side surface of the lower plate spring, the lower plate spring being made of fiber-reinforced resin;

an upper plate spring disposed above the lower plate spring with respect to a vertical direction of the plate spring unit and forming a gap between the upper plate spring and the lower plate spring, the upper plate spring including a middle portion pressed by a pressing member of a cross beam of the railcar bogie, the pressing member pressing an upper side surface of the middle portion of the upper plate spring, and the upper plate spring being made of fiber-reinforced resin;

a middle spacer sandwiched between a middle portion of the lower plate spring and the middle portion of the upper plate spring; and

an end spacer sandwiched between the end portion of the lower plate spring on an upper side surface of the lower plate spring and an end portion of the upper plate spring on a lower side surface of the upper plate spring, the end spacer being configured to allow relative displacement in the longitudinal direction between the end portion of the lower plate spring and the end portion of the upper plate spring.

2. The plate spring unit according to claim 1 , wherein the middle portion of the lower plate spring and the middle portion of the upper plate spring sandwich the middle spacer so as to be displaceable relative to each other in the longitudinal direction.

3. The plate spring unit according to claim 2 , wherein:

the middle spacer includes:

a lower groove portion extending in the longitudinal direction and is-open downward with respect to the vertical direction of the plate spring unit, and

an upper groove portion extending in the longitudinal direction and open upward with respect to the vertical direction of the plate spring unit, and

the lower plate spring is fitted to the lower groove portion from below the lower groove portion with respect to the vertical direction of the plate spring unit, and

the upper plate spring is fitted to the upper groove portion from above the upper groove portion with respect to the vertical direction of the plate spring unit.

4. A railcar bogie comprising:

the plate spring unit according to claim 3 ;

the cross beam supporting a carbody of a railcar; and

a plurality of axle boxes, including the axle box of the railcar bogie, arranged at respective car longitudinal direction sides of the cross beam and accommodating respective bearings supporting an axle,

wherein the axle box, the end portion of the lower plate spring, the end spacer, and the end portion of the upper plate spring are arranged overlapping one another when viewed from the vertical direction.

5. The railcar bogie according to claim 4 , further comprising a restricting member disposed between the lower plate spring and the upper plate spring so as to be located at a car longitudinal direction middle side of the end spacer, the restricting member being configured to restrict a movement of the end spacer relative to the axle box toward the car longitudinal direction middle side by more than a predetermined distance.

6. A railcar bogie comprising:

the plate spring unit according to claim 2 ;

the cross beam supporting a carbody of a railcar; and

a plurality of axle boxes, including the axle box of the railcar bogie, arranged at respective car longitudinal direction sides of the cross beam and accommodating respective bearings supporting an axle,

wherein the axle box, the end portion of the lower plate spring, the end spacer, and the end portion of the upper plate spring are arranged overlapping one another when viewed from the vertical direction.

7. The railcar bogie according to claim 6 , further comprising a restricting member disposed between the lower plate spring and the upper plate spring so as to be located at a car longitudinal direction middle side of the end spacer, the restricting member being configured to restrict a movement of the end spacer relative to the axle box toward the car longitudinal direction middle side by more than a predetermined distance.

8. The plate spring unit according to claim 1 , wherein:

the middle spacer includes:

a lower groove portion extending in the longitudinal direction and open downward with respect to the vertical direction of the plate spring unit, and

an upper groove portion extending in the longitudinal direction and open upward with respect to the vertical direction of the plate spring unit, and

the lower plate spring is fitted to the lower groove portion from below the lower groove portion with respect to the vertical direction of the plate spring unit, and

the upper plate spring is fitted to the upper groove portion from above the upper groove portion with respect to the vertical direction of the plate spring unit.

9. A railcar bogie comprising:

the plate spring unit according to claim 8 ;

the cross beam supporting a carbody of a railcar; and

a plurality of axle boxes, including the axle box of the railcar bogie, arranged at respective car longitudinal direction sides of the cross beam and accommodating respective bearings supporting an axle,

wherein the axle box, the end portion of the lower plate spring, the end spacer, and the end portion of the upper plate spring are arranged overlapping one another when viewed from the vertical direction.

10. The railcar bogie according to claim 9 , further comprising a restricting member disposed between the lower plate spring and the upper plate spring so as to be located at a car longitudinal direction middle side of the end spacer, the restricting member being configured to restrict a movement of the end spacer relative to the axle box toward the car longitudinal direction middle side by more than a predetermined distance.

11. A railcar bogie comprising:

the plate spring unit according to claim 1 ;

the cross beam supporting a carbody of a railcar; and

a plurality of axle boxes, including the axle box of the railcar bogie, arranged at respective car longitudinal direction sides of the cross beam and accommodating respective bearings supporting an axle,

wherein the axle box, the end portion of the lower plate spring, the end spacer, and the end portion of the upper plate spring are arranged overlapping one another when viewed from the vertical direction.

12. The railcar bogie according to claim 11 , further comprising a supporting member disposed at an upper portion of the axle box, the supporting member including an upper surface supporting a lower surface of the end portion of the lower plate spring, the lower surface of the end portion of the lower plate spring and the upper surface of the supporting member including respective flat surfaces.

13. The railcar bogie according to claim 12 , further comprising a restricting member disposed between the lower plate spring and the upper plate spring so as to be located at a car longitudinal direction middle side of the end spacer, the restricting member being configured to restrict a movement of the end spacer relative to the axle box toward the car longitudinal direction middle side by more than a predetermined distance.

14. The railcar bogie according to claim 11 , further comprising a restricting member disposed between the lower plate spring and the upper plate spring so as to be located at a car longitudinal direction middle side of the end spacer, the restricting member being configured to restrict a movement of the end spacer relative to the axle box toward the car longitudinal direction middle side by more than a predetermined distance.