![]() Device for obtaining given variation of ignition lead angle
专利摘要:
1479205 Ignition systems; timing ignition G HARTIG 7 June 1974 [26 July 1973] 25310/74 Heading F1B Apparatus for varying the ignition timing in an internal combustion engine comprises pulse generation means for deriving from a rotating part of the engine a sequence of pulses all of which are of substantially equal length, counting means 8 for performing a succession of counting operations during each of which the number of pulses occurring during a time t is counted, a control device for performing an arithmetical operation on the number of pulses counted during each time t or for altering the time t of the next count in dependence on the number of pulses counted during the preceding counting operation, the result of each arithmetical operation or the number of pulses counted during the altered time t being a reference count representing the angle of spark advance α relative to the top dead centre, counting means, which are the same as or different from the firstmentioned counting means for counting, starting from each reference count, from an arbitrary phase position which is advanced from the top dead centre by an angle # until a predetermined total number of pulses has been counted which represent the angle # and means for causing an ignition spark to be produced each time the predetermined total number of pulses has been counted whereby each spark occurs advanced by the angle α relative to the top dead centre. Fig. 4 shows how the circuit of Fig. 3 can be modified to be in accordance with the invention. The reference numeral 50 indicates a coding matrix which has a series of first inputs 51 and a second series of inputs 52a, 52b, 52c and so on. The inputs 51 are shown as connected to the outputs 10 to 13 of the counter 8. Values of operating parameters of the engine are fed through the inputs 52a, 52b and 52c. These values may represent engine temperature intake manifold vacuum, throttle valve position and so on. The pulses from the transmitter 2 are fed to the counter 8 through a gate 6 which is kept open by the function generator 7 for a predetermined time t. The auxiliary pulse from the transmitter 1 is in such a phase that the take over of the numerical condition of the counter 8 by the counter 18 is just ahead of the arbitrary phase position. The output of the counter 18 passes to a comparator 33. At the predetermined value the comparator delivers a pulse at the output terminal 35, this pulse comprising an ignition pulse. The time t can be changed according to engine parameters for example engine temperature intake manifold vacuum or the temperature of an after-combustion reactor. In a modification, not shown, the coding matrix comprises a quadruple NAND gate which has inverted and non-inverted inputs coupled to counting inputs of the firstmentioned counting means. The output of the NAND gate is connected to an input of a NOR gate which is coupled by at least one other input to a transducer of the engine. In Fig. 7 (not shown) the output 53 of the matrix 50 is no longer connected to the function generator 7 but is used to influence the counter directly without changing the time t. The control pulse which occurs at the output 20 of the transmitter 1 can be fed to the input 24 with a time and/or angle delay. Other embodiments are described. A preferred form of the function generator 7 is described. 公开号:SU772493A3 申请号:SU742045824 申请日:1974-07-25 公开日:1980-10-15 发明作者:Хартиг Др.Гунтер 申请人:За витель 54) УСТРОЙСТВО ДЛЯ ПОЛУЧЕНИЯ ЗАДАННОГО ЗАКОНА ИЗМЕНЕНИЯ УГЛА ОПЕРЕЖЕНИЯ ЗАЖИГАНИЯ (ФРГ); IPC主号:
专利说明:
This invention relates to internal combustion engines and, in particular, to ignition systems for an internal combustion engine. Devices are known for obtaining a predetermined law of changing the ignition advance angle, comprising an engine mode measurement sensor, a main counter, the inputs of which are connected to sensors forming a series of electrical pulses, synchronous to the rotational speed of the internal combustion engine, and the output of the initial number counter, and the output from energy storage device, and a seed meter control circuit comprising a function generator and configured to change the magnitude of the seed number of at least one even operation, and logic circuit l According ztomu adjustment device can be realized ignition timing depending on the number of revolutions and the load on the engine is warm. For lower toxicity, it is important to take into account the engine's operating conditions; particular mode of operation of the cold engine and idling mode. The known devices do not provide an optimum dependence of the advance angle of the ignition on the frequency of rotation when the engine is cold and in the cold run mode. The aim of the invention is to optimize the dependence of the advance angle on the engine speed. The goal is achieved by the fact that the control circuit of the initial number counter contains a coding matrix, the inputs of which are connected to the outputs of the initial number counter and the output is connected to the input of the primary synchronizer correction or the input of the function generator. The coding matrix is made in 20 form of a multiple circuit NOT, the inverting and non-inverting inputs of which are connected to the counting outputs of the initial number counter, and the output to the input of the NOT-OR circuit connected to at least one input to the engine mode measurement sensor and the output to the function generator. In addition, the device is characterized in that the meter control circuit the initial number is made in the form of a digital converter including a binary counter and a frequency generator The initial number counter is adapted to perform the functions of a binary digital counter counter. The seed counter has an additional control input for changing the counting direction. The function generator is made in the form of a digital sweep generator containing a frequency generator. FIG. .1 shows a washer with a sensor / m pulses; in fig. 2 - angles corresponding to the rotation of the engine crankshaft; the advance angle ot of the ZEOKigani, the comparison angle f, | Corner correction P, as well as the top dead point Oy, a point Z, corresponding to the ignition of the mixture in the engine cylinder; point C of the arbitrary position of the crankshaft in FIG. 3 is a diagram of a preferred embodiment of the proposed device; in fig. 4 is a diagram of a device with a coding.) By a sliding matrix; in fig. 5 is a part of the device circuit; FIG. b is a graph of the dependence of the rotational speed advance angle realized by the device in FIG. 5, in FIG. 7 is a graph of the angle of advance versus rotational speed, implemented by the circuit in FIG. eight; in fig. 8 is a diagram of the proposed device, an option; in fig. 9 is a diagram of a digital converter in FIG. 10 - the same, simplified version; in fig. 11 shows the dependence of the advance angle on the rotation frequency realized in the device in FIG. 10 in FIG. 12 - function generator, mainly used for the implementation of the proposed device. Sensors 1 and 2 of electric impulses are mounted on washer 3 rigidly fixed on the engine crankshaft and equipped with two ranges of 4 and 5 teeth, external and internal. The teeth of external range 4, which interact with sensor 2, are evenly distributed around the circumference (only part of the teeth is shown), the teeth of internal range 5, which interact with sensor 1, are significantly smaller than the teeth of range 4. The tooth of range 4 and sensor 4 are designed to receive main pulses , and the teeth of range 5 and sensor 1 for receiving pulses controlling the operation of the checkers and determining the phases of the main pulses. The proposed device, the preferred option (fig.Z), includes the main counter b, inputs 7 and 8 of which are connected to sensors 1 and 2 of electrical impulses, inputs 9-12 with outputs 13-16 of the counter 17 are the prime number, and the output is energy storage device (not shown) through the matrix il8 compare. The output of the comparison matrix is connected to the input 19 of the initial number counter through the pulse shaper 20 and to the input 21 of the function generator 22 having a control input 23. The output 24 of the function generator is connected via a valve 25 to the input of the initial number counter 17. An energy storage device (not shown) is connected to output 26. The scheme works as follows. The main counter 6 continuously receives pulses from sensor 2. In addition, it receives pulses from the counter 17 of the initial number. The phase position of the auxiliary pulse from sensor 1 is such that the reception of the counting state of the counter 17 by the main counter b occurs just before the crankshaft takes a point (Fig. 1). Since the matrix 18 of comparison of the ignition is 1mixed to a certain counting state (the main number is equal to the number of pulses from Y to OT, the ignition pulse at the output 26 is at the number of pulses from sensor 2 equal to the difference between the main number and the number of pulses (initial number) , previously obtained by the counter 6 from the counter 17. Thus, the ignition impulse is in accordance with the rotation of the engine crankshaft through an angle (FIG. 1), i.e. ahead of the upper dead center. The ignition pulse appearing at the output 26 simultaneously passes through the driver 20 to the reset input 19 of the initial number counter 17 and to the trigger input 21 of the generator 22. The function generator 22 produces an output signal of duration t, starting when a pulse appears at the input 21. The duration can be changed through the input 23 depending on the engine parameters in (e.g., tagging temperature, inlet pressure, temperature of the combustion chamber). After starting the generator 22, the valve 25 is open for a predetermined time t and the initial number counter 17 received from the sensor 2 the number of pulses corresponding to this time. Therefore, the higher the engine speed, the greater the number of pulses received by counter 17 and, accordingly, the greater number of pulses will be transferred to counter 6 of the main number before the crankshaft reaches 4p (figure 1).
权利要求:
Claims (7) [1] Therefore, an increase in the number of pulses sensed by the counter 17 over time t will lead to an increase in the ignition advance angle oL with increasing engine speed. In a number of cases it may be necessary to change the shape of the graph of ignition advance over the engine's rotational frequency, for example, when the temperature or load changes. Thus, for example, it may be necessary to slowly increase the ignition advance angle as a function of frequency, and if a certain predetermined magnitude is reached, a constant advance angle not dependent on frequency may be required. To set the desired angle ahead of the circuit, the device is slightly modified (see Fig.4). A coding matrix 27 is inserted into the device, having a number of inputs 28 (first), 29-21 (second) and output 32 connected to. generator input 22 functions. The scheme works as follows. Information on engine parameters from engine measurement sensors (not shown), such as temperature, vacuum at the inlet, throttle position, etc., is entered through inputs 29, for example, internal system information through inputs 28. Depending on the programming of the coding matrix, one or more information is obtained that controls the generator of the 22 functions. The coding matrix can be simplified (see Fig. 5), then the graph of the dependence of the advance angle on the frequency takes the form shown in FIG. 6. The circuit (Fig. 5) includes a non-OR circuit 33, the first input of which is connected to the output of the non-AND circuit 34. The output 35 of the circuit 33 NOT-OR is connected to a sensor giving, for example, with full gas, an O signal. Inverting the inputs of the circuit are not-and 3.4 connected to the inputs 14 and 15 of the counter 17 of the initial number, and the non-inverting inputs are connected to the inputs of 13 and 16 of figure 4. The output 36 of the circuit 33 is NOT-OR connected to the input of the generator 22 of functions (figure 4 ). The circuit works as follows. At a certain state of motion of the bodies, for example, with full gas, at the input 35 of the NOT-OR circuit 33 an O state signal appears and at output 36 a positive pulse occurs at the moment when the counter 17 is set to the state 9, which corresponds to binary combination 1001. This positive impulse affects the time t of generator 22, depending on the generator circuit, in the direction of its increase or decrease. In the diagram in FIG. 3, the function generator 22 is arranged so that a positive pulse reduces the time t to zero and the counter 17 of the initial 4iic does not receive more input pulses, remaining in state 9. This achieves a transition of the graph of Fig. 6c, horizontal straight at the rotation frequency vigatel n. In the absence of a full gas signal, the counter 17 counts to the state determined by its internal construction, in the present case to the state 15, and only after that the graph of the dependence of the advance angle on the frequency will turn into a horizontal line. The dotted line in FIG. 6). It is possible to influence the generator time t in such a way that the dependence of the advance angle on the frequency h will have the form shown in Fig. 7. The scheme with which the graph of FIG. 7 can be obtained is depicted in FIG. The output of the coding matrix 27 is connected to the correction input input 37 of the initial number counter 17 via a logic blocking circuit 38. To bring the circuit 38 back to its initial state, it also has an input 39 electrically connected with driver 2Q. The scheme works as follows. The command appearing at the input 37 performs the adjustment of the initial number counter, so in the plot of the angle c versus frequency (FIG. 7), at the rotational frequency Hj, a jump occurs from the angle ci to the angle c (2 After the ignition pulse forms circuit 38 is brought to the initial state via input 39, and thus the initial number is adjusted only n times (preferably one) per the counter's duty cycle. If a jump is required in the direction of increasing the angle, then no logical blocking circuit is required. In addition, a triggering signal appears in the counting cycle of the initial number only once per cycle. It may be appropriate in certain engine modes to set the initial number counter before the start of a new cycle not to the 0000 state, but to a predetermined binary value depending on the engine mode. This value can be obtained using a digital converter, the circuit of which and its connection to the system are shown in Fig.9. Digital converter 40 (Fig. 9) contains a frequency generator 41, whose frequency varies depending on the engine speed, function generator 42, which produces a pulse S at its output 43 if a voltage pulse appears at the trigger input 44. In the rest, the function generator 42 corresponds to the function generator 22, and the duration of its pulse can be changed using an appropriate signal at input 45. In addition, the digital converter contains a 4b gate NOT-npejjHasHa to pass the frequency generator pulses to the binary counter 47 for a time while there is a signal at input 48 of the circuit. The number of pulses of the generator 41 is counted by the counter 47 and is transmitted to the inputs of the counter 17 of the seed number. It should be noted that the trigger pulse at the input 44, the generator 42, as well as the pulse at the input 49 of the counter 47, must be such that the counting process in the counter 47 was completed before the appearance of a reset command at the input 19 of the counter 17 of the initial number. Thus, with the help of the preliminary scheme, it is possible to vary the ignition advance characteristic depending on the engine parameters. In addition, depending on the output number of the counter 47, the comparison matrix can be reprogrammed and the comparison matrix can be simplified in Fig. 9 (see Fig. 10). In the simplification, there is no digital converter counter, and its functions are simultaneously performed by an initial number counter. In the circuit of FIG. 10, the output pulse of the mapper 20 is supplied, unlike the circuit of FIG. 9, not to the trigger input 21 of the generator 22, but to the input of the generator 42 of functions, the pulses of which, in turn, are fed to the input 21 generators 22 functions. When the impulse of the mapper 20 appears, the counter 17 is set to the initial position and at the same time the generator 42 is started so that at its output 4 a pulse of 5-t duration is formed. This pulse opens the valve 46 through the input 48, and by it, the pulses of the generator 42 functions fall through the counting input 50 into the counter 17 of the initial number. Frequency generator 41 is controlled via input 51, depending on engine parameters. If the additional one shown in phantom in Fig. 10 is applied, with the connection between output 43 and input 52 of counter 17, the latter will start counting in reverse direction during the duration of the pulse 5. In the general case, the counter 17 reaches the end of the pulse S of a predetermined (positive and negative) value, depending on the duration 5 and the frequency of the frequency generator 41, as well as on the counting direction of the seed counter. The falling edge of the pulse 5 starts the generator 22 and the process of counting the pulses of the sensor 2 begins with the count 17 of the initial number. Regarding the circuit in Fig. 3 and its modification, it should be noted that it is possible to supply the control sensor 1 from the output to the input 8 (Fig. 3) with a delay in angle or in time, or simultaneously with a delay in angle and in time. This can be done, for example, by connecting a counter in front of input 8, controlled by pulses appearing in sensor 1 and counting pulses from sensor 2. The counter can be programmed so that, at a given counting state, it gives a pulse to input 8. Delay over time can be carried out with the help of one or several elements of the backplate. With such a modification, a flexible change in the angle from the engine parameters can be achieved, which is shown by the graphs in FIG. 11 (suppose the time delay is constant. If there is no delay in the circuit, then the circuit shown in FIG. 3 is modified in FIG. 5, a graph of the dependence of the angle Y of Fig. 1 on the rotational frequency can be obtained. If there is a delay element in the circuit, then the graph of the dependence of the correction angle p) of Fig.1 on the rotational frequency has the form 54. The actual plot 55 shows the dependence of the angle of advance ignition from you, if the delay member is formed from summing the graphs 53 and 54. By reducing the amount of delay, depending on the actual angle cL frequency will lie in the field, between graphs 53 and 55. In a preferred embodiment fig.12.pokazan generator circuit 22 functions. The generator 56 functions performed in the form of a digital sweep generator and contains the generator 57 frequencies, the output 58 of which is connected to the input of the circuit 59 NOT-AND. The other input 60 of the NAND circuit is connected to the output 61 of the trigger relay 62. The output of the NAND circuit 59 is connected to the input 63 of the counter 64, and the output 65 of the latter is connected to the reset input of the trigger RS relay 62. The circuit works as follows. When a command is received at input 61 of relay 62, state 1 is generated so that counter 64 counts the Fault 63 counting pulses from generator 57. When counter 64 reaches a predetermined counting value, a pulse appears at the output of the trigger relay 62. The trigger relay overturns into the quiescent state, and output O appears at output 61. Due to this mode, output 24 triggers a pulse, the duration -t of which is determined by the generator frequency 57 and the set state of counter 64. These values, in his sight Radiation can be controlled jointly or autonomously via input 23, and preferably the mechanical control of the frequency of the generator 57. In a particular case, the generator 57 can be implemented as a converter 40, for example, if both are controlled by the same1 1 and the same input values. digital mode, the device according to the invention can be easily implemented as an integrated unit. In conclusion, it should be noted that the main counter in all variants of execution can be used as a counter of the initial number. Since the pulses are controlled, for example, by the function generator 22, h. hanging from the engine mode, these pulses can also be used for other processes controlling the engine or the device driven by it. Claim 1. Device for obtaining the desired law of changing the ignition advance angle, comprising an engine mode measurement sensor, a main counter, the inputs of which are connected to sensors forming series of electrical impulses synchronous to the rotational speed of the engine's internal combustion engine and the initial counter the numbers, and the output with the energy storage device, the control circuit of the initial number meter, with the generator of the functions holding and configured to change the value of the initial number, at least A single counting operation, and logical schemes, characterized in that, in order to optimize the dependence of the ignition advance angle on the engine rotational speed, the initial number meter control scheme contains an encoding matrix, the inputs of which are connected to the outputs of the initial number counter, and the output with the input correction of the initial number counter or function generator input. [2] 2. Device POP.1, characterized in that the encoding matrix is made in the form of a multiple circuit, the non-inverting and non-inverting inputs of which are connected to the counting outputs of the initial number counter, and the output - to the input of the circuit non-or connected to at least one An input with an engine measurement sensor and an output with a function generator. [3] 3. A device according to Claims 1 and 2, characterized in that the output of the coding matrix is connected to the correction input of the initial number counter via a logical blocking circuit. [4] 4. The device according to Claim 1, which is based on the fact that the control circuit of the initial number counter is made in the form of a digital converter that includes a binary counter and a frequency generator. [5] 5. The device according to Claims 1 and 4, which is characterized by the fact that the initial number counter is adapted to perform the functions of a binary counter of a digital converter. [6] 6. The device according to claim 5, wherein the initial number counter is provided with an additional control input for changing the counting direction. [7] 7. A device in accordance with one of the claims 1 to 6, characterized in that the function generator is made in the form of a digital sweep generator including a frequency generator. Sources of information taken into account during the examination 1. Patent of Germany No. 2010999, cl. 46 to 3/00, omission. 1971 (prototype). / / X ag.6 . ti Pin.ia ", / f. St Sj / 55 23 oSif 63 .eleven . Zf S6 5.7 58 60 21 -O 62 Si
类似技术:
公开号 | 公开日 | 专利标题 SU772493A3|1980-10-15|Device for obtaining given variation of ignition lead angle SU910132A3|1982-02-28|Electronic ignition system for internal combustion engine US4176629A|1979-12-04|Electric control method for fuel injection and ignition timing CA1049090A|1979-02-20|Means and method for controlling the occurrence and the duration of time intervals during which sparks are provided in a multicylinder internal combustion engine GB1479467A|1977-07-13|Circuit arrangements US4073270A|1978-02-14|Electronically-controlled fuel injection system GB1434309A|1976-05-05|Systems for controlling the ignition timing of internal combustion engines US4018197A|1977-04-19|Spark ignition systems for internal combustion engines US4466406A|1984-08-21|Regulating device for control variables of an internal combustion engine EP0024733A2|1981-03-11|Method and system for operating an internal combustion engine at maximum torque under varying operating conditions US4481912A|1984-11-13|Device for camshaft control US4082069A|1978-04-04|Method and apparatus to determine the timing of cyclically repetitive events, particularly ignition instant for internal combustion engines US4175506A|1979-11-27|Electric ignition control system US3976043A|1976-08-24|Means and method for controlling the occurrence and the duration of time intervals during which sparks are provided in a multicylinder internal combustion engine US4284046A|1981-08-18|Contactless ignition system for internal combustion engine US3990412A|1976-11-09|Injection control system for an internal combustion engine US6012427A|2000-01-11|Internal combustion engine spark scheduling US4576129A|1986-03-18|Fuel injection system for internal combustion engines EP0044656A1|1982-01-27|Method of and apparatus for optimising the operation of an internal combustion engine JP4375685B2|2009-12-02|Engine control device US4175508A|1979-11-27|Method and apparatus to generate a trigger pulse within a time range, particularly ignition pulses in internal combustion engines US4366792A|1983-01-04|Angle of advance correction signal generator SE447750B|1986-12-08|PROCEDURE FOR AUTOMATIC CONTROL OF THE IGNITION OBJECTS OF A COMBUSTION ENGINE AS A DEVICE FOR EXECUTING THE PROCEDURE US4498444A|1985-02-12|Method of controlling engine US4109616A|1978-08-29|Injection control system for an internal combustion engine
同族专利:
公开号 | 公开日 DD113084A5|1975-05-12| FR2238850B1|1978-03-24| US3941103A|1976-03-02| NL7409841A|1975-01-28| IT1030041B|1979-03-30| FR2238850A1|1975-02-21| JPS5819852B2|1983-04-20| DE2339755A1|1975-02-27| JPS5043331A|1975-04-19| DE2339755B2|1976-12-09| GB1479205A|1977-07-06| CH565945A5|1975-08-29|
引用文献:
公开号 | 申请日 | 公开日 | 申请人 | 专利标题 DE1917389A1|1969-04-03|1970-10-22|Gunter Hartig|Method and device for generating triggering pulses| US3757755A|1971-10-14|1973-09-11|Inst Gas Technology|Engine control apparatus| US3749073A|1971-11-23|1973-07-31|Gte Sylvania Inc|Electronic ignition timing system for internal combustion engines| US3738339A|1971-12-06|1973-06-12|Gen Motors Corp|Electronic ignition spark advance system| JPS513842B2|1972-09-12|1976-02-06|IT1049544B|1974-07-31|1981-02-10|Ducellier & Cie|AUTOMATIC IGNITION ADVANCE DEVICE ACCORDING TO THE SPEED QUOTE OF ROTATION OF AN INTERNAL COMBUSTION ENGINE| DE2512166C2|1975-03-20|1982-01-14|Robert Bosch Gmbh, 7000 Stuttgart|Method for defining a repetitive process, in particular an ignition process, and device for carrying out the method| US4104997A|1976-01-20|1978-08-08|Motorola, Inc.|Multiple slope ignition spark timing circuit| DE2623613C2|1976-05-26|1982-12-23|Robert Bosch Gmbh, 7000 Stuttgart|Ignition system with an ignition angle adjustment device| JPS59705B2|1976-06-09|1984-01-07|Hitachi Ltd| JPS6132498B2|1977-02-08|1986-07-28|Tokyo Shibaura Electric Co| DE2711432A1|1977-03-16|1978-09-21|Bosch Gmbh Robert|IGNITION SYSTEM, IN PARTICULAR FOR COMBUSTION MACHINERY| JPS5412011A|1977-06-30|1979-01-29|Nissan Motor Co Ltd|Intake-air amount detecting apparatus for internal combustion engine| US4231331A|1977-08-08|1980-11-04|Nissan Motor Company, Limited|Pulse generator of the corona discharge type for sensing engine crankshaft angle on an engine control system| GB2033003B|1978-10-27|1982-11-24|Hughes Microelectronics Ltd|Control circuit for controlling the timing of spark ignition of an internal combustion engine| FR2412207A1|1978-12-15|1979-07-13|Sp O P Kon|Phase related starting pulse generator for vehicle engines - has sensors mounted in association with flywheel and coupled to comparator after pulse interval and variable frequency division correction| US4273089A|1979-09-12|1981-06-16|Essex Group, Inc.|Open loop computer-controlled spark ignition timing system| US4306536A|1980-02-01|1981-12-22|Brunswick Corporation|Pulse controlled spark advance unit for an internal combustion engine ignition system| DE3045246C2|1980-12-01|1987-05-14|Atlas Fahrzeugtechnik Gmbh, 5980 Werdohl, De| US4378004A|1981-02-23|1983-03-29|Motorola Inc.|Engine control system with cylinder identification apparatus| EP0066975B2|1981-06-05|1989-12-13|LUCAS INDUSTRIES public limited company|Internal combustion engine function control system| FR2521645A3|1982-02-17|1983-08-19|Ducellier & Cie|Electronic ignition system for IC engines - uses computer accepting engine data for use as pointer to look-up table held in ROM giving correct advance | DE19912770A1|1999-03-22|2000-09-28|Bosch Gmbh Robert|Ignition control device and method|
法律状态:
优先权:
[返回顶部]
申请号 | 申请日 | 专利标题 CH1093673A|CH565945A5|1973-07-26|1973-07-26| 相关专利
Sulfonates, polymers, resist compositions and patterning process
Washing machine
Washing machine
Device for fixture finishing and tension adjusting of membrane
Structure for Equipping Band in a Plane Cathode Ray Tube
Process for preparation of 7 alpha-carboxyl 9, 11-epoxy steroids and intermediates useful therein an
国家/地区
|