fig1 is a cross - sectional view of the resin - molded stator showing an embodiment of the present invention . fig2 is a cross - sectional view of the section a – a ′ in fig1 , and fig3 is a cross - sectional view of the section b – b ′ in fig2 . the steps taken to manufacture this resin - molded stator are described below . a slot provided in a stator core 1 consisting of laminated electromagnetic steel plates is covered with a liner 8 which is made of a polyamideimides non - woven fabric , and then stator coils 2 each consisting of a conductor provided with insulation are wound around the stator core 1 . after this , the stator core 1 around which the stator coils 2 have been wound is built into a housing 4 which has a bearing installation recess 3 at the end of the housing . of the two surfaces vertical to the axis of the stator core 2 , only the surface located at the opposite side to the bearing installation recess 3 in the housing 4 when the stator core 1 is to be built into the housing is coated with a polytetrafluoroethylene resin film which has been pre - processed into the same shape as that of the electromagnetic steel plates of the stator core 1 , and the coated surface mentioned above functions as a non - adhesive treatment section 5 to prevent bonding between the stator core 1 and the molding resin 7 to be later added . the polytetrafluoroethylene resin film is bridged , does not fuse during molding , and functions as non - adhesive structure . although , in the present embodiment , the resin film is formed as a non - adhesive treatment section 5 between molding resin and stator core at one side , this film can also be provided at both sides . in the present embodiment , as shown in fig1 , since the resin film also functions as a mold for resin - molding the housing 4 located at one side , this film gives non - adhesiveness to one side . in the housing 4 , a plurality of injection - molding gate positions 10 functioning as resin injection ports for resin - molding the housing 4 are provided circumferentially on the side thereof so as to ensure equal injection of the resin , and these gates are filled with the molding resin . molds are provided at the opposite side to the resin injection ports and at the inner circumferential side . the housing 4 is also provided with an agency 6 through which the coolant for cooling the rotary machine is to be passed . next , the housing 4 into which the stator core 1 with the stator coils 2 wound around it , is preheated to 100 ° c . and then set in a mold which has been heated to 150 ° c . beforehand . after this , the polyester - based molding resin that has been filled with the powder of calcium carbonate and aluminum oxide is injection - molded at a pressure of 4 mpa , and hereby , the stator coil 2 inside the slot of the stator core 1 and the stator coil 2 at the coil end emerging from the stator core 1 are molded . as shown in fig2 , a recess 9 for preventing the rotational vibration of the coil end portion is provided in the housing 4 . two types of resin are available as examples of the polyester - based molding resin mentioned above : ( 1 ) molding resin created by mixing resin , calcium carbonate powder , and alumina powder at the weight rate of 1 : 1 : 1 , with the resin consisting of 100 weight parts of maleic acid - containing unsaturated polyester and 40 weight parts of styrene monomer , and ( 2 ) molding resin created by mixing resin , calcium carbonate powder , and alumina powder at the weight rate of 1 : 1 : 1 , with the resin consisting of 100 weight parts of isophthalic acid - containing unsaturated polyester and 40 weight parts of styrene monomer . fig4 is a cross - sectional view of the rotary machine pertaining to the present invention . a rotor 19 and a shaft 21 having slip rings 20 built thereinto are attached to the resin - molded stator shown in fig1 . after this , rear plates 23 which have a diode 22 and the like , are attached , then a brush assembly 24 and a regulator 25 are installed , and a rear bracket 26 is installed . the axial length ( w ) of a coil end space 28 provided between the resin - molded section at the coil end portion and the rear plate 23 is set to a value equal to , or greater than , the value derived from the product of ( a × t × lc ), where a is the thermal expansion coefficient of the stator coil conductor , t is the maximum temperature that the conductor reaches during the operation of the rotary machine , and lc is the total axial length of the conductor that includes said coil end . a stringent acceleration test for increasing the output of the thus - manufactured rotary machine from the level under its stopped status to the maximum achievable level within a short time has been repeated five times , with the result that no abnormality has been observed . although an example of a rotary machine with slip rings , a brush assembly , and a diode , has been shown in the present embodiment , it is obvious that the embodiment can be similarly applied to a rotary machine not equipped with these components . fig5 is a cross - sectional view of the resin - molded stator shown as a comparative example against the present invention . the steps taken to manufacture this resin - molded stator are described below . a slot provided in a stator core 1 consisting of laminated electromagnetic steel plates is covered with a liner which is made of a polyamideimides non - woven fabric , and then stator coils 2 each consisting of a conductor provided with insulation are wound around the stator core 1 . after this , the stator core 1 around which the stator coils 2 have been wound is built into a housing 4 which has a bearing installation recess 3 at the end of the housing . or the housing 4 is provided with an agency 6 through which the coolant for cooling the rotary machine . next , the housing 4 into which the stator core 1 with the stator coils 2 wound around it , is preheated to 100 ° c . and then set in a mold which has been heated to 150 ° c . beforehand . after this , the polyester - based molding resin that has been filled with the powder of calcium carbonate and aluminum oxide is injection - molded at a pressure of 4 mpa , and hereby , the stator coil 2 inside the slot of the stator core 1 and the stator coil 2 at the coil end emerging from the stator core 1 are molded . a rotor 19 and a shaft 21 having slip rings 20 built thereinto are attached to the resin - molded stator . after this , rear plates 23 which have a diode 22 and the like , are attached , then a brush assembly 24 and a regulator 25 are installed , and a rear bracket 26 is installed . a stringent acceleration test for increasing the output of the thus - manufactured rotary machine from the level under its stopped status to the maximum achievable level within a short time has been repeated five times , with the result that insulation breakdown has occurred between phases . fig6 is a partial cross - sectional view of a brushless rotary machine using the resin - molded stator which employs concentrated winding in the present invention . the steps taken to manufacture this rotary machine are described below . a protrusion provided on a stator core 1 consisting of laminated electromagnetic steel plates is covered with a liner which is made of a polyamideimides non - woven fabric , and then stator coils 2 each consisting of a conductor provided with insulation are wound around the stator core 1 . after this , the stator core 1 around which the stator coils 2 have been wound is built into a housing 4 . of the two surfaces vertical to the axis of the stator core 2 , only the surface located at the opposite side to the bearing installation recess in the housing 4 when the stator core 1 is to be built into the housing is coated with a polytetrafluoroethylene resin film which has been pre - processed into the same shape as that of the electromagnetic steel plates of the stator core 1 , and the coated surface mentioned above functions as a non - adhesive treatment section 5 to prevent bonding between the stator core 1 and the molding resin 7 to be later added . the housing 4 is also provided with an agency 6 through which the coolant for cooling the rotary machine is to be passed . next , the housing 4 into which the stator core 1 with the stator coils 2 wound around it , is preheated to 100 ° c . and then set in a mold which has been heated to 150 ° c . beforehand . after this , a pressure of 4 mpa is applied to the polyester - based molding resin that has been filled with the powder of calcium carbonate and aluminum oxide . thereby , similarly to embodiment 1 described above , in the housing 4 , a plurality of injection - molding gate positions 10 functioning as resin injection ports for resin - molding the housing 4 are provided circumferentially on the side thereof so as to ensure equal injection of the resin , and these gates are filled with the molding resin to provide injection - molding , with the result that the stator coil 2 inside the slot of the stator core 1 and the stator coil 2 at the coil end emerging from the stator core 1 are molded . a recess 9 for preventing the rotational vibration of the coil end portion is also provided in the housing 4 . as shown in fig6 , a shaft 21 into which a rotor 19 has been built is attached to the resin - molded stator . after this , an end plate 27 having a bearing mounted therein is installed . the axial length ( w ) of a coil end space 28 provided between the resin - molded section at the coil end portion and the rear plate 27 is set to a value equal to , or greater than , the value derived from the product of ( a × t × lc ), where a is the thermal expansion coefficient of the stator coil conductor , t is the maximum temperature that the conductor reaches during the operation of the rotary machine , and lc is the total axial length of the conductor that includes said coil end . a stringent acceleration test for increasing the output of the thus - manufactured rotary machine from the level under its stopped status to the maximum achievable level within a short time has been repeated five times , with the result that no abnormality has been observed .