Abstract:
Disclosed herein are electric vehicle control device which can distribute the heat generated by the semiconductor devices in the DC/AC converter efficiently. Also disclosed herein are methods of converting DC to AC while keeping the heat value of the semiconductor devices stable.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is, based upon and claims the benefit of priority from Japanese Patent Application No. 2011-080240, filed Mar. 31, 2011, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    This embodiment is related with the electric vehicle control device which uses a refrigeration unit. 
       BACKGROUND 
       [0003]    Generally the permanent magnet synchronous motor can use energy efficiently as compared with an induction motor. A permanent magnet synchronous motor has less generation of heat than an induction motor. Therefore, the permanent magnet synchronous motor can save weight compared to an induction motor. Therefore, the demand for a permanent magnet synchronous motor is increasing in recent years. 
         [0004]    The permanent magnet synchronous motor needs to give and control voltage from a VVVF inverter according to the position of the rotor of each permanent magnet synchronous motor. Therefore, the inverter needs to perform individual control for every permanent magnet synchronous motor. The VVVF inverter of one set each of exclusive use of a permanent magnet synchronous motor has been located. The gate control device was set in each VVVF inverter, in order to control each VVVF inverter. 
         [0005]    For this reason, in the system configuration which controls the conventional permanent magnet synchronous motor individually, the number of apparatus increased and enlargement of the whole device and the increase in cost had become a problem. 
     
    
     
       BRIEF DESCRIPTION OF THE FIG 
         [0006]      FIG. 1  shows the circuit lineblock diagram of a first embodiment. 
           [0007]      FIG. 2  is a representative circuit schematic of the semiconductor device package of a first embodiment. 
           [0008]      FIG. 3  is the voltage output and rise-in-heat figure of a semiconductor device package of a first embodiment. 
           [0009]      FIG. 4  is an outline view of a first embodiment. 
           [0010]      FIG. 5  is a circuit lineblock diagram of a Second Embodiment. 
           [0011]      FIG. 6  is a circuit lineblock diagram of a Third Embodiment. 
           [0012]      FIG. 7  is U phase circuit diagram of 3 level power converter of fourth embodiment. 
           [0013]      FIG. 8  is an outline view of 3 level power converter of fourth embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    To achieve the above-described object, A electric vehicle control device according to the present disclosure comprising a motor, a plurality of inverters comprising a semiconductor device package and a cooler unit to transform DC power to AC power to supply AC power to the motor with switching a semiconductor device, wherein the semiconductor device package stored at least two semiconductor device, wherein the cooler unit connected to semiconductor device package of plurality inverter to cool the semiconductor device package of plurality inverter. 
       First Embodiment 
       [0015]    A first embodiment is described with reference to several figures.  FIG. 1  is a circuit lineblock diagram of a first embodiment.  FIG. 2  is a representative circuit schematic of the semiconductor device package of a first embodiment.  FIG. 3  is the voltage output and rise-in-heat figure of a semiconductor device package of a first embodiment.  FIG. 4  is an outline view of a first embodiment. 
       (Element: 4 in 1 Inverter Unit) 
       [0016]    With reference to  FIG. 1 , in the electric vehicle control device of this embodiment, the first 4 in 1 inverter unit&#39;s direct-current side comprises current collector  4 , high speed circuit breaker  5 , short circuit contact machine  6  for charge resistance, charge resistor  7 , open contact machine  8 , filter reactor  9 , excess voltage control resistor  10 , switching element  11  for excess voltage control, wheel  12 , and filter reactor  14 . The alternating current side of a 4 in 1 inverter comprises permanent magnet synchronous motor  2  ( 2   a,    2   b,    2   c,    2   d ), motor opening contact machine  3  ( 3   a,    3   b,    3   c,    3   d ), and current sensor  34  ( 34   a,    34   b,    34   c,    34   d ). 
         [0017]    Current collector  4  is connected with high speed circuit breaker  5 , and high speed circuit breaker  5  is connected with short circuit contact machine  6  for charge resistance. The parallel circuit which comprises contact machine  6  and resistor  7  is connected with contact machine  8 . Contact machine  8  is connected with filter reactor  9 . Filter reactor  9  is connected with the end of first 4 in 1 inverter unit  1 , and the other end of first 4 in 1 inverter unit  1  is connected with wheel  12 . Series circuit  19  for excess voltage control comprises resistor  10  and switching element  11 . One terminal side of series circuit  19  is connected between filter reactor  9  and first 4 in 1 inverter unit  1 , and, another terminal side of series circuit  19  for excess voltage control is connected between first 4 in 1 inverter unit  1  and wheel  12 . Both ends of filter capacitor  14  are connected between direct-current circuit  19  for excess voltage control, and 1st 4 in 1 inverter unit  1 . In the alternating current side of first 4 in 1 inverter unit  1 , current sensors  34   a,    34   b,    34   c,  and  34   d  are set on  3  phase lines. Four permanent magnet synchronous motors  2   a,    2   b,    2   c,  and  2   d  are connected to first 4 in 1 inverter unit  1  via motor opening contact machines  3   a,    3   b,    3   c,  and  3   d.    
         [0018]    First 4 in 1 inverter unit  1  comprises VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.  VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d  are connected in parallel. 
         [0019]    VVVF inverter  21   a  comprises U phase semiconductor device package  22   a,  V phase semiconductor device package  22   b,  W phase semiconductor device package  22   c,  and filter capacitor  13   a  for inverters. U phase semiconductor device package  22   a,  V phase semiconductor device package  22   b,  and W phase semiconductor device package  22   c  are connected in parallel. Filter capacitor  13   a  for inverters is connected to the direct-current side of W phase semiconductor device package  22   c  in parallel. As for VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d,  filter capacitors  13   b,    13   c,  and  13   d  are connected similarly. 
       (Elements: Semiconductor Device Package) 
       [0020]      FIG. 2  is a representative circuit schematic of a semiconductor device package. 
         [0021]      FIG. 3  is a figure showing the switching state of the semiconductor device in a semiconductor device package, and the temperature state of the semiconductor device package by the switching. 
         [0022]    As shown in  FIG. 2 , right side element  24   a  of an upper arm and lower arm negative side element  24   b  are connected to semiconductor device package  22  in series. Power supply  25  is connected to the output side of negative side element  24   b  and the input side of right side element  24   a.  Voltage is outputted from neutral point  26  of right side element  24   a  and negative side element  24   b.  Current flows into right side element  24   a  from power supply  25  by right side element  24   a  being set to ON, and negative side element  24   b  being come by off, and it is outputted from neutral point  26 . By right side element  24   a  being come by off, and negative side element  24   b  being set to ON, current flows into negative side element  24   b  from power supply  25 , and it is outputted from neutral point  26 . A direct current is transformed into an alternating current by repeating such switching. 
         [0023]      FIG. 3(   a ) shows the voltage output by switching of a right side element, and  FIG. 3(   b ) shows the voltage output by switching of a negative side terminal. What compounded  FIG. 3(   a ) and the voltage output of ( b ) serves as a voltage output of the semiconductor device package  22  whole of  FIG. 3(   c ).  FIG. 3(   d ) shows the graph which showed the rise in heat by the voltage output of a right side element.  FIG. 3(   e ) shows the graph which showed the rise in heat by the voltage output of a negative side terminal. As shown in  FIG. 3(   d ), the temperature of right side element  24   a  rises, when right side element  24   a  of  FIG. 3(   a ) is an ON state, and does not rise in an OFF state. Therefore, the temperature of right side element  24   a  carries out gradual increase by repeating switching operation ON/OFF. As shown in  FIG. 3(   e ), the temperature of negative side element  24   b  will rise by repeating switching operation ON/OFF of  FIG. 3(   b ) like a right side element. However, the ON state of right side element  24   a  and the ON state of negative side element  24   b  are performed one after the other within semiconductor device package  22 . Therefore, the heat value of the semiconductor device package  22  whole becomes fixed as shown in  FIG. 3(   f ). 
         [0024]    It is 4 in 1 inverter unit  1  which unitized four sets of VVVF inverters  21  which use the above semiconductor device packages  22 .  FIG. 4  shows the appearance of the device of the first 4 in 1 inverter unit  1 . As shown in  FIG. 4 , 1st 4 in 1 inverter unit  1  is the composition that one cooler structure  23  was installed for four VVVF inverters  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.  VVVF inverters  21   a,    21   b,    21   c,  and  21   d  are attached to heat-receiving board  23   a  which composes a part of cooler structure  23 . Radiator  23   b  is connected to the opposite field of which VVVF inverters  21   a,    21   b,    21   c,  and  21   d  of heat-receiving board  23   a  are attached. 
       Operation 
       [0025]    An operation of the electric vehicle control device of this embodiment is explained. Wire direct-current electric power is supplied to an electric vehicle control device via current collector  4 . The direct-current electric power supplied via current collector  4  passes along high speed circuit breaker  5 , charge resistor  7 , contact machine  8 , and filter reactor  9 , and is supplied to filter capacitor  14 . A Direct current flows into filter capacitor  14  and the filter capacitor ( 13   a,    13   b,    13   c,    13   d ) of each inverter connected in parallel. A Direct current&#39;s accumulation of sufficient electric charge will throw in contact machine  6 . 
         [0026]    The direct-current electric power from wire passes along high speed circuit breaker  5 , short circuit contact machine  6  for charge resistance, contact machine  7  for opening, and filter reactor  9 , and is supplied to first 4 in 1 inverter unit  1 . 
         [0027]    When direct-current electric power is supplied to first 4 in 1 inverter unit  1 , Direct-current electric power is supplied to the semiconductor device which is store in U,V,W phase semiconductor device package  22   a,    22   b  and  22   c  of VVVF inverter  21   a,    21   b,    21   c,  and  21   d.    
         [0028]    Direct-current electric power is transformed into alternating current electric power by switching of the semiconductor device of VVVF inverter  21 . The transformed alternating current electric power is supplied to four permanent magnet synchronous motors  2 , and the drive of permanent magnet synchronous motor  2  is started. In this embodiment, when the wire voltage of 1500V is impressed to first 4 in 1 inverter unit  1 , the same voltage of 1500V also as VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d  is impressed. If the voltage of 1500V is impressed to each which is VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d,  the current will flow into permanent magnet synchronous motor  2 , and permanent magnet synchronous motor  2  will be driven. 
         [0029]    Thus, although permanent magnet synchronous motor  2  will be in the state which can be driven by the electric energy conversion of the semiconductor device of first 4 in 1 inverter unit  1 , but an electric-energy-conversion loss occurs in the case of the electric energy conversion. An electric-energy-conversion loss serves as heat, and is generated from a semiconductor device. The heat generated from the semiconductor device spreads to heat-receiving board  23   a.  The heat transferred to heat-receiving board  23   a  will spread to radiator  23   b,  which will radiate heat from radiator  23   b  to outside. 
         [0030]    Therefore, the heat generated by electric-energy-conversion loss will be canceled outside the product, without stopping at the inside of the product. When a control device (not shown) detects a breakdown and one set of VVVF inverter  21  opens breaker  5  within first 4 in 1 inverter unit  1  during the drive of an electric vehicle control device, four sets of all VVVF inverters  21  will be opened. 
         [0031]    When direct-current voltage sensor  15  detects that the direct-current electric power supplied to 1st 4 in 1 inverter unit  1  became excessive, a control device turns on switching element  11  and makes direct-current electric power consume by resistor  10 . The control device is controlling ON and OFF of switching element  11  by the output of a direct-current voltage sensor. 
       Effect 
       [0032]    The electric vehicle control device composed in this way can be cooled more efficiently than the conventional radiator, because the heat value of first 4 in 1 inverter unit  1  is also equalized with the whole device, although electric-energy-conversion units of plurality are stored. When the semiconductor device was being individually installed in radiator  23   b  like before, the installing space of  24  semiconductor devices was needed, but it was able to be considered as  12  installing spaces by using a device package. The operating efficiency of cooler  23  improved by combining two semiconductor devices so that the quantity of heat generated from a device package might become uniform, and installation by a small space was attained. 
         [0033]    Part mark have been reduced by making filter reactor  9 , excess voltage control resistor  10 , and switching element  11  for excess voltage control common in a circuit. 
         [0034]    It is also possible to store direct-current voltage sensor  15 , current sensors  34   a,    34   b,    34   c,  and  34   d,  and motor opening contact machines  3   a,    3   b,    3   c,  and  3   d  in 4 in 1 inverter unit  1 . 
         [0035]    It is possible by being able to acquire the same effect as this embodiment also in that case, and storing many devices in one case to simplify wiring and to easy manufacture of the whole device and installation. 
         [0036]    It is also possible to delete filter capacitors  13   a,    13   b,    13   c,  and  13   d,  and to work in four sets of VVVF inverters  21  by shared filter capacitor  14  in  FIG. 1 . It becomes possible to share the right side conductor by the side of a direct current, and the negative side conductor by the side of a direct current between sharing filter capacitor  14  between four sets of VVVF inverters  21  by four sets of VVVF inverters. Therefore, it is more possible than the case where filter capacitors  13   a,    13   b,    13   c,  and  13   d  are installed to reduce part mark. 
       Second Embodiment 
       [0037]    A Second Embodiment is described with reference to figures.  FIG. 5  is a circuit line block diagram of a Second Embodiment. About what takes the same composition as  FIGS. 1  thru/or  4 , a same sign is attached and explanation is omitted. 
       (Elements) 
       [0038]    The connection states of a VVVF inverter and direct current voltage sensors are different between first embodiment of electric vehicle control device and second embodiment. The point is explained below. 
         [0039]    The inside of 4 in 1 inverter unit  1  of a second comprises VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.  VVVF inverter  21   a  and VVVF inverter  21   b  which were connected in series compose inverter series circuit  33   a,  and compose VVVF inverter  21   c  and VVVF inverter  21   d  which were connected in series from inverter series circuit  33   b.  Inverter series circuit  33   a  and inverter series circuit  33   b  are connected in parallel. Filter capacitor  13   a  for inverters is connected to the direct-current side of W phase semiconductor device package  22   c  of VVVF inverter  21   a.  Direct-current voltage sensor  32   a  is connected to the direct-current side of W phase semiconductor device package  22   c  in parallel with filter capacitor  13   a  for inverters. As for VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d,  filter capacitors  13   b,    13   c,  and  13   d  for inverters and direct-current voltage sensors  32   b,    32   c,  and  32   d  are connected with the same composition as VVVF inverter unit  21   a.    
       Operation 
       [0040]    An operation of the electric vehicle control device of this embodiment is explained. For example, when the wire voltage of 1500V is impressed to 4 in 1 inverter unit  30  of a second, the same voltage of 1500V also as inverter series circuits  33   a  and  33   b  is impressed. Within inverter series circuit  33   a  and  33   b,  the wire voltage of 1500V is divided, and the voltage which is 750V is impressed to each VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.    
         [0041]    The current corresponding to the voltage flows and permanent magnet synchronous motor  2  is driven by the current. 
         [0042]    In that case, direct-current voltage sensor  32   a  supervises the voltage state of VVVF inverter unit  21   a  by detecting the voltage value of filter capacitor  13   a  for inverters. Direct-current voltage sensor  32   b  supervises the voltage state of VVVF inverter unit  21   b  by detecting the voltage value of filter capacitor  13   b  for inverters. Direct-current voltage sensor  32   c  supervises the voltage state of VVVF inverter unit  21   c  by detecting the voltage value of filter capacitor  13   c  for inverters. Direct-current voltage sensor  32   d  supervises a VVVF inverter unit&#39;s  21   d  voltage state by detecting the voltage value of filter capacitor  13   d  for inverters. 
       Effect of this Embodiment 
       [0043]    In addition to the effect of first embodiment, such an electric vehicle control device of composition divided the wire voltage which is impressed to VVVF inverter  21 . Therefore, switch a semiconductor device on lower voltage than first embodiment, it becomes possible to reduce the heat generated as an electric-energy-conversion loss. 
         [0044]    Miniaturization of cooler structure and energy saving at the time of a device drive can be achieved by generating of heat being reduced. 
         [0045]    It can control by detecting the voltage value of each VVVF inverter  21  more correctly using direct-current voltage sensor  32 . 
       Third Embodiment 
       [0046]    A Third Embodiment is described with reference to figures.  FIG. 6  is a circuit lineblock diagram of a Third Embodiment. About what takes the same composition as  FIGS. 1  thru/or  4 , a same sign is attached and explanation is omitted. 
       (Elements) 
       [0047]    The connection states of a VVVF inverter, direct current voltage sensors and filter capacitor are different between first embodiment of electric vehicle control device and the third embodiment. The point is explained below. 
         [0048]    The inside of third 4 in 1 inverter unit  42  comprises VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.  VVVF inverter  21   a  and VVVF inverter  21   b  which were connected in parallel compose inverter parallel circuit  43   a.  VVVF inverter  21   c  and VVVF inverter  21   d  which were connected in parallel consist of inverter parallel circuits  43   b.  Inverter parallel circuit  43   a  and inverter parallel circuit  43   b  are connected in series. Direct-current voltage sensor  40   a  connected in parallel with filter capacitor  41   a  and filter capacitor  41   a  are connected to the direct-current side of inverter parallel circuit  43   a.  As for inverter parallel circuit  43   b,  filter capacitor  41   b  and direct-current voltage sensor  40   b  are connected with the same composition as inverter parallel circuit  43   a.    
       Operation 
       [0049]    Next, the operation of this embodiment is explained. In this embodiment, when the wire voltage of 1500V is impressed to third 4 in 1 inverter unit  42 , the voltage of 750V by which partial pressure was carried out is impressed to inverter parallel circuits  43   a  and  43   b.  If the voltage of 750V is impressed to inverter parallel circuits  43   a  and  43   b,  the voltage of 750V will be impressed to each which is VVVF inverter  21   a,  VVVF inverter  21   b,  VVVF inverter  21   c,  and VVVF inverter  21   d.  The current corresponding to the voltage flows and permanent magnet synchronous motor  2  is driven by the current. 
       Effect of this Embodiment 
       [0050]    This embodiment can obtain the same operation as first embodiment. In addition to the effect of first embodiment, such an electric vehicle control device of composition divided the wire voltage which is impressed to VVVF inverter  21 . Therefore, switch a semiconductor device on lower voltage than first embodiment, it becomes possible to reduce the heat generated as an electric-energy-conversion loss. Miniaturization of cooler structure and energy saving at the time of a device drive can be achieved by generating of heat being reduced. 
         [0051]    Because wire voltage detects the voltage of inverter parallel circuits  43   a  and  43   b  by which partial pressure is carried out by direct-current voltage sensors  40   a  and  40   b,  a voltage value required for control can be detected, and part mark can be made less than a Second Embodiment. 
       Fourth Embodiment 
       [0052]    Fourth embodiment is described with reference to figures.  FIG. 7  is U phase circuit diagram of 3 level power converter of fourth embodiment.  FIG. 8  is an outline view of the power converter of fourth embodiment. About what takes the same composition as  FIGS. 1  thru/or  4 , a same sign is attached and explanation is omitted. 
       (Elements) 
       [0053]    This embodiment applies semiconductor device package  22  of first embodiment to the fourth inverter unit that is a power converter of three levels. Hereafter, the point is explained. As shown in  FIG. 7 , U phase circuit of 3 level power converter of this embodiment comprises first element  65   a,  second element  65   b,  third element  65   c,  fourth element  65   d  and first clamp diode  69   a,  and second clamp diode  69   b.    
         [0054]    Hereafter, composition of U phase circuit  66  is explained as a example. The first element  65   a,  the second element  65   b,  the third element  65   c,  and the fourth element  65   d  are U phase series circuits connected in series. First clamp diode  69   a  and second clamp diode  69   b  are connected in series. The end of 1st clamp diode  65   a  is connected between the first element  65   a  and the second element  65   b.  The end of clamp diode  65   b  of a second is connected between the third element  65   c  and the fourth element  65   d.  The first element  65   a  and third element  65   c  are stored by first U phase semiconductor device package  66   a.  The second element  65   b  and fourth element  65   d  are stored by second U phase semiconductor device package  66   b.  First clamp diode  69   a  and second clamp diode  69   b  are stored by third U phase semiconductor device package  66   c.  Like U phase circuit  66 , first V phase semiconductor device package  67   a  of V phase circuit  67 , V phase semiconductor-device-package  67   c,  second V phase semiconductor device package  67   b  and the third reach, first W phase semiconductor device package  68   a  of W phase circuit  68 , second W phase semiconductor device package  68   b,  and third W phase semiconductor device package  68   c  are composed. 
         [0055]    Next, with reference to  FIG. 9 , U phase circuit  66 , V phase circuit  67 , and W phase circuit  68  which are established in heat-receiving board  23   a  of cooler structure  23 , are explained. As shown in  FIG. 9 , U phase circuit  66  and W phase circuit  68  are located at the end of heat-receiving board  23   a,  and V phase circuit  67  is arranged between U phase circuit  66  and W phase circuit  68 . U phase circuit  66  is located with the permutation of first U phase semiconductor device package  66   a,  second U phase semiconductor device package  66   b,  and third U phase semiconductor device package  66   c.  V phase circuit  67  is located with the permutation of the third semiconductor device package  67   c  of V phase, the second semiconductor device package  67   b  of V phase, and the first semiconductor device package  67   a  of V phase. W phase circuit  68  is located with the permutation of the first semiconductor device package  68   a  of W phase, the third semiconductor device package  68   c  of W phase, and the second semiconductor device package  68   b  of W phase. 
       Operation 
       [0056]    In U phase circuit  66 , when a semiconductor device performs switching for electric energy conversion, second element  65   b  Reaches and the third element  65   c  of the inductance becomes the largest. Second element  65   b  of the heat value and the third element  65   c  of the heat value becomes the largest. Next, the heat value from the first element  65   a  and fourth element  56   d  becomes large. 
         [0057]    There is least heat value from first clamp diode  69   a  and second clamp diode  69   b.  V phase circuit  67  and W phase circuit  68  are also the same. Therefore, the heat value of the first semiconductor device package  66   a,    67   a,    68   a  which stored combining the first element  64   a  and third element  65   c  is equivalent to the heat value of semiconductor device packages  66   b,    67   b,  and  68   b  of the second stored combining the second element  65   b  and fourth element  65   d.  The heat value of the third semiconductor device package  66   c,    67   c,    68   c  which stored combining first clamp diode  69   a  and second clamp diode  69   b  is lower than the heat value of the first semiconductor device package  66   a,    67   a,    68   a  and the second semiconductor device packages  66   b,    67   b,    68   b.    
       Effect of this Embodiment 
       [0058]    In the electric vehicle control device of this embodiment, the third semiconductor device package  66   c,    67   c  and  68   c  which have little heat value are located between the first semiconductor device package  66   a,    67   a,  and  68   a  which have much heat value and the second semiconductor device packages  66   b,    67   b,  and  68   b  which have much heat value. Therefore, the heat is easy to be equalized with heat-receiving board  2 , and it make easy to cool efficiently at cooler guard  23 . Therefore, it is able to make 3 level power converter miniaturization, unless 3 level power converter has with many semiconductor devices sets. 
         [0059]    The semiconductor device package  22  can apply not only for 4 in 1 inverter unit but also other composition, such as a 2 in 1 inverter unit which comprise two inverter. 
         [0060]    While certain embodiments of the invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.